Heat-related emergency hospitalizations for respiratory diseases in the Medicare population

The spatial distribution of heat related hospitalizations and classification of the most dangerous heat events in California at a small-scale level

Many studies have explored the impact of extreme heat on health, but few have investigated localized heat-health outcomes across a wide area. We examined fine-scale variability in vulnerable areas, considering population distribution, local weather, and landscape characteristics. Using 36 different heat event definitions, we identified the most dangerous types of heat events based on minimum, maximum, and diurnal temperatures with varying thresholds and durations. Focusing on California's diverse climate, elevation, and population distribution, we analyzed hospital admissions for various causes of admission (2004-2013). Our matching approach identified vulnerable zip codes, even with small populations, on absolute and relative scales. Bayesian Hierarchical models leveraged spatial correlation. We ranked the 36 heat event types by attributable hospital admissions per zip code and provided code, simulated data, and an interactive web app for reproducibility. Our findings showed high variation in heat-related hospitalizations in coastal cities and substantial heat burdens in the Central Valley. Diurnal heat events had the greatest impact in the Central Valley, while nighttime extreme heat events drove burdens in the southeastern desert. This spatially informed approach guides local policies, prioritizing dangerous heat events to reduce the heat-health burden. The methodology is applicable to other regions, informing early warning systems and characterizing extreme heat impacts.

[Effects of high thermal stress on health-a nationwide analysis based on statutory health insurance routine data between 2012 and 2021]

BACKGROUND

The extent to which statutory health insurance (SHI) data can be used to map associations between thermal stress and heat-related diseases is still unclear. The aim of this study is to analyse the association between climate variability and heat-associated diseases using insurance data.

METHODS

The study is based on claims data (outpatient and stationary) from health insurance companies in Germany for the years 2012-2021, covering approximately 11 million people with statutory health insurance. Four heat-related ICD-10 diagnoses were considered: T67 (heat and sun damage), E86 (volume depletion), N17 (acute renal failure) and N19 (renal insufficiency). Thermal conditions were quantified using meteorological variables. The evaluation was carried out on a federal state-specific basis for the second and third quarters (Q2, Q3) using descriptive methods and correlation analyses with repeated measurements.

RESULTS

The years 2016, 2018 and 2020 were characterised by high temperatures. Compared with Q2, Q3 was associated with higher thermal stress and more heat-related diagnoses on average during the entire observational period. Nationally, diagnoses of heat and sun damage (outpatient) correlated with the number of hot days (rmw = 0.86 [0.81; 0.90]). Although heat stress is lower in the second quarter, a similar correlation is found here (rmw = 0.76 [0.68; 0.82]). This striking association was also maintained when analysing the federal states specifically.

DISCUSSION

The article shows that associations between thermal stress and morbidity can also be found in routine SHI data. Against the background of an increase in high thermal stress due to climate change, this article highlights the need for adaptation measures.

Compound impact of heatwaves on vulnerable groups considering age, income, and disability

The increasing frequency and intensity of heat waves due to climate change and urbanization have caused serious public health problems, especially in urban areas in which the heat effects are amplified by dense infrastructure and limited green space. This study examined the impact of heatwaves on vulnerable populations in Korean cities, focusing on how age, income, and disability are associated with higher health risks. In our study, we analyzed healthcare big data from 2010 to 2022 for seven major Korean cities. We employed a distributed lag non-linear model to assess the relationship between heat exposure and health outcomes, allowing us to quantify the compounded vulnerabilities due to socioeconomic and physical factors. The results showed that the association of compounded vulnerability was more pronounced in patients hospitalized through the emergency room, a severe health outcome, than in patients with mild health outcome such as outpatient visits for heat-related illnesses. The association of compounded vulnerability was particularly evident in the elderly population. These findings suggest the need for tailored heatwave preparedness strategies for vulnerable groups, contributing to the broader discourse on climate adaptation and public health resilience.

Concurrent ozone and high temperature exacerbates nasal epithelial barrier damage in allergic rhinitis mice: Insights from the nasal transcriptome and nasal microbiota

The global ambient temperature has been rising in recent decades and high temperature is usually accompanied by ozone (O3) pollution. Environmental change is an underlying factor for the increased prevalence of respiratory allergic disease. However, the potential mechanisms are complex and remain elusive. This study was performed to reveal toxic effects and molecular mechanisms of O3 or/and high temperature induced allergic rhinitis (AR) deterioration. The results indicated that O3 and high temperature co-exposure exacerbated rhinitis symptoms, destroyed ultrastructure of nasal mucosa and down-regulated the expression of nasal epithelial barrier structural proteins ZO-1 and occludin. Moreover, the levels of total protein and lactate dehydrogenase (LDH) in nasal lavage fluid and the levels of IL-1β and TNF-α in serum also exhibited a significant upward trend. Transcriptomic analysis revealed that immune and inflammatory signaling pathways such as IL-17 signaling pathway was involved in the combined toxicity of O3 and high temperature. Microbiome examination showed that Prevotella and Elizabethkingia were linked to nasal injury. What's more, spearman correlation analysis revealed correlations among nasal microbiota dysbiosis, inflammation and injury. To sum up, the present study assessed the combined toxicity of O3 and high temperature and found potential mechanisms, which provided important experimental evidence for making preventive intervention strategies and protecting vulnerable populations.

Burden of non-communicable diseases attributable to high temperature in a changing climate from 1990 to 2019: a global analysis

BACKGROUND

With global climate change, the health threats of ambient high temperature have received widespread attention. However, latest spatio-temporal patterns of the non-communicable diseases (NCDs) burden attributable to high temperature have not been systematically reported. We aimed to analyze vulnerable areas and populations based on a detailed profile for the NCDs burden attributable to high temperature globally.

METHODS

We obtained data from the Global Burden of Diseases (GBD) Study (2019) to describe the temporal and spatial patterns of NCDs burden attributable to high temperature globally from 1990-2019. Then we analyzed the differences by region, sex, and socio-demographic index (SDI). Finally, the age‑period‑cohort (APC) model was utilized to explore the age, period, and cohort effects of NCDs mortality caused by high temperature.

RESULTS

In 2019, the number of deaths and Disability-adjusted life years (DALYs) from high-temperature-related NCDs was about 150,000 and 3.4 million globally, of which about 70% were in South Asia and North Africa and Middle East, and the burden was higher in men. Among 204 countries and territories, the highest age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) were observed in Oman and United Arab Emirates, respectively. The global burden showed an upward trend from 1990 to 2019, with an EAPC of 3.66 (95%CI: 3.14-4.18) for ASMR and 3.68 (95%CI: 3.16-4.21) for ASDR. Cardiovascular diseases were the main contributors to the global burden of high-temperature-related NCDs in 2019. The age and period effect in APC model showed an increasing trend globally. There was a significant negative correlation between SDI and both ASMR (r = -0.17) and ASDR (r = -0.20) from 1990 to 2019.

CONCLUSION

There was an increasing trend of the global burden of high-temperature-related NCDs. The burden was likely to be higher in males and the elderly, as well as in countries and regions with less economically and socially developed and in tropical climates. Surveillance and prevention measures should be implemented with a focus on these vulnerable areas and susceptible populations.

Ambient temperature and risk of cardiovascular and respiratory adverse health outcomes: a nationwide cross-sectional study from Spain

AIMS

We assessed the association of temperature and temperature variability with cause-specific emergency hospitalizations and mortality from cardiovascular and respiratory diseases in Spain, as well as the effect modification of this association by individual and contextual factors.

METHODS AND RESULTS

We collected data on health (hospital admissions and mortality), weather (temperature and relative humidity), and relevant contextual indicators for 48 Spanish provinces during 2004-2019. The statistical analysis was separately performed for the summer (June-September) and winter (December-March) seasons. We first applied a generalized linear regression model with quasi-Poisson distribution to estimate daily province-specific temperature-health associations, and then we fitted multilevel multivariate meta-regression models to the evaluate effect modification of the contextual characteristics on heat- and cold-related risks. High temperature increased the risk of mortality across all cardiovascular and respiratory diseases, with the strongest effect for hypertension (relative risk (RR) at 99th temperature percentile vs. optimum temperature: 1.510 [95% empirical confidence interval {eCI} 1.251 to 1.821]), heart failure (1.528 [1.353 to 1.725]), and pneumonia (2.224 [1.685 to 2.936]). Heat also had an impact on all respiratory hospitalization causes (except asthma), with similar risks between pneumonia (1.288 [1.240 to 1.339]), acute bronchitis and bronchiolitis (1.307 [1.219 to 1.402]), and chronic obstructive pulmonary disease (1.260 [1.158 to 1.372]). We generally found significant risks related to low temperature for all cardiovascular and respiratory causes, with heart failure (RR at 1st temperature percentile vs. optimum temperature: 1.537 [1.329 to 1.779]) and chronic obstructive pulmonary disease (1.885 [1.646 to 2.159]) exhibiting the greatest risk for hospitalization, and acute myocardial infarction (1.860 [1.546 to 2.238]) and pneumonia (1.734 [1.219 to 2.468]) for mortality. Women and the elderly were more vulnerable to heat, while people with secondary education were less susceptible to cold compared to those not achieving this educational stage. Results from meta-regression showed that increasing heating access to the highest current provincial value (i.e. 95.6%) could reduce deaths due to cold by 59.5% (57.2 to 63.5).

CONCLUSION

Exposure to low and high temperatures was associated with a greater risk of morbidity and mortality from multiple cardiovascular and respiratory conditions, and heating was the most effective societal adaptive measure to reduce cold-related mortality.

Assessment of heat stress contributing factors in the indoor environment among vulnerable populations in Klang Valley using principal component analysis (PCA)

Rising global temperatures can lead to heat waves, which in turn can pose health risks to the community. However, a notable gap remains in highlighting the primary contributing factors that amplify heat-health risk among vulnerable populations. This study aims to evaluate the precedence of heat stress contributing factors in urban and rural vulnerable populations living in hot and humid tropical regions. A comparative cross-sectional study was conducted, involving 108 respondents from urban and rural areas in Klang Valley, Malaysia, using a face-to-face interview and a validated questionnaire. Data was analyzed using the principal component analysis, categorizing factors into exposure, sensitivity, and adaptive capacity indicators. In urban areas, five principal components (PCs) explained 64.3% of variability, with primary factors being sensitivity (health morbidity, medicine intake, increased age), adaptive capacity (outdoor occupation type, lack of ceiling, longer residency duration), and exposure (lower ceiling height, increased building age). In rural, five PCs explained 71.5% of variability, with primary factors being exposure (lack of ceiling, high thermal conductivity roof material, increased building age, shorter residency duration), sensitivity (health morbidity, medicine intake, increased age), and adaptive capacity (female, non-smoking, higher BMI). The order of heat-health vulnerability indicators was sensitivity > adaptive capacity > exposure for urban areas, and exposure > sensitivity > adaptive capacity for rural areas. This study demonstrated a different pattern of leading contributors to heat stress between urban and rural vulnerable populations.

The impact of increasing ambient temperature on allergic rhinitis: A systematic review and meta-analysis of observational studies

INTRODUCTION

Global warming appears to initiate and aggravate allergic respiratory conditions via interaction with numerous environmental factors. Temperature, commonly identified as a factor in climate change, is important in this process. Allergic rhinitis, a common respiratory allergy, is on the rise and affects approximately 500 million individuals worldwide. The increasing ambient temperature requires evaluation regarding its influence on allergic rhinitis, taking into account regional climate zones.

METHODS

A detailed search of PubMed, EMBASE, Scopus, Web of Science, MEDLINE, and CINAHL Plus databases, was conducted, encompassing observational studies published from 1991 to 2023. Original studies examining the relationship between increasing temperature and allergic rhinitis were assessed for eligibility followed by a risk of bias assessment. Random effects meta-analysis was utilized to measure the association between a 1 °C increase in temperature and allergic rhinitis-related outcomes.

RESULTS

20 studies were included in the qualitative synthesis, with nine of them subsequently selected for the quantitative synthesis. 20 included studies were rated as Level 4 evidence according to the Oxford Centre for Evidence-Based Medicine, and the majority of these reported good-quality evidence based on the Newcastle-Ottawa Quality Rating Scale. Using the Risk of Bias In Non-Randomized Studies of Exposure tool, the majority of studies exhibit a high risk of bias. Every 1 °C increase in temperature significantly raised the risk of allergic rhinitis-related outcomes by 29 % (RR = 1.26, 95 % CI: 1.11 to 1.50). Conversely, every 1 °C rise in temperature showed no significant increase in the odds of allergic rhinitis-related outcomes by 7 % (OR = 1.07, 95 % CI: 0.95 to 1.21). Subsequent subgroup analysis identified climate zone as an influential factor influencing this association.

CONCLUSION

It is inconclusive to definitively suggest a harmful effect of increasing temperature exposure on allergic rhinitis, due overall very low certainty of evidence. Further original research with better methodological quality is required.

Heat Exposure and Cause-Specific Hospital Admissions in Spain: A Nationwide Cross-Sectional Study

BACKGROUND

More frequent and intense exposure to extreme heat conditions poses a serious threat to public health. However, evidence on the association between heat and specific diagnoses of morbidity is still limited. We aimed to comprehensively assess the short-term association between cause-specific hospital admissions and high temperature, including the added effect of temperature variability and heat waves and the effect modification by humidity and air pollution.

METHODS

We used data on cause-specific hospital admissions, weather (i.e., temperature and relative humidity), and air pollution [i.e., fine particulate matter with aerodynamic diameter ≤ 2.5 μ m (PM 2.5 ), fine particulate matter with aerodynamic diameter ≤ 10 μ m (PM 10 ), NO 2 , and ozone (O 3 )] for 48 provinces in mainland Spain and the Balearic Islands between 1 January 2006 and 31 December 2019. The statistical analysis was performed for the summer season (June-September) and consisted of two steps. We first applied quasi-Poisson generalized linear regression models in combination with distributed lag nonlinear models (DLNM) to estimate province-specific temperature-morbidity associations, which were then pooled through multilevel univariate/multivariate random-effect meta-analysis.

RESULTS

High temperature had a generalized impact on cause-specific hospitalizations, while the added effect of temperature variability [i.e., diurnal temperature range (DTR)] and heat waves was limited to a reduced number of diagnoses. The strongest impact of heat was observed for metabolic disorders and obesity [relative risk (RR) = 1.978; 95% empirical confidence interval (eCI): 1.772, 2.208], followed by renal failure (1.777; 95% eCI: 1.629, 1.939), urinary tract infection (1.746; 95% eCI: 1.578, 1.933), sepsis (1.543; 95% eCI: 1.387, 1.718), urolithiasis (1.490; 95% eCI: 1.338, 1.658), and poisoning by drugs and nonmedicinal substances (1.470; 95% eCI: 1.298, 1.665). We also found differences by sex (depending on the diagnosis of hospitalization) and age (very young children and the elderly were more at risk). Humidity played a role in the association of heat with hospitalizations from acute bronchitis and bronchiolitis and diseases of the muscular system and connective tissue, which were higher in dry days. Moreover, heat-related effects were exacerbated on high pollution days for metabolic disorders and obesity (PM 2.5 ) and diabetes (PM 10 , O 3 ).

DISCUSSION

Short-term exposure to heat was found to be associated with new diagnoses (e.g., metabolic diseases and obesity, blood diseases, acute bronchitis and bronchiolitis, muscular and connective tissue diseases, poisoning by drugs and nonmedicinal substances, complications of surgical and medical care, and symptoms, signs, and ill-defined conditions) and previously identified diagnoses of hospital admissions. The characterization of the vulnerability to heat can help improve clinical and public health practices to reduce the health risks posed by a warming planet. https://doi.org/10.1289/EHP13254.

Thermal stress and hospital admissions for cardiorespiratory disease in Brazil

The growing body of scientific literature underscores the intricate relationship between meteorological conditions and human health, particularly in the context of extreme temperatures. However, conventional temperature-centric approaches often fall short in capturing the complexity of thermal stress experienced by individuals. Temperature alone, as a metric, fails to encompass the entirety of the thermal stress individuals face, necessitating a more nuanced understanding. In response to this limitation, climatologists have devised thermal indices-composite measures meticulously crafted to reflect the intricate interplay of meteorological factors influencing human perception of temperature. Recognizing the inadequacy of simplistic temperature-focused methodologies, our study aims to address the multifaceted nature of thermal stress. In this study, we explored the association between thermal indices and hospital admissions for circulatory and respiratory diseases in Brazil. We used an extensive dataset spanning 11 years (2008-2018) from the Brazilian Ministry of Health, encompassing a total of 23,791,093 hospitalizations for circulatory and respiratory diseases. We considered four distinct thermal indices-Discomfort Index (DI), Net Effective Temperature (NET), Humidex (H), and Heat Index (HI). We used an extension of the two-stage design with a case time series to assess this relationship. In the first stage, we applied a distributed lag non-linear modeling framework to create a cross-basis function. We next applied quasi-Poisson regression models adjusted by time-varying confounders. In the second stage, we applied meta-analysis with random effects to estimate the national relative risk (RR). Our findings suggest robust variations among the thermal indices under examination. These variations underscore the intricate nature of associations between temperature and health, with each index capturing distinct aspects of thermal conditions. Our results indicate that extreme thermal conditions, both at the low and high ends, are associated with increased risks of hospital admissions. The diverse impact observed among different indices emphasizes the complex interplay between various meteorological factors and their specific physiological consequences. This underscores the necessity for a comprehensive comprehension of temperature metrics to guide precise public health interventions, recognizing the multifaceted nature of temperature-health relationships.

Pulmonary vascular disease, environmental pollution, and climate change

Pollution and climate change constitute a combined, grave and pervasive threat to humans and to the life-support systems on which they depend. Evidence shows a strong association between pollution and climate change on cardiovascular and respiratory diseases, and pulmonary vascular disease (PVD) is no exception. An increasing number of studies has documented the impact of environmental pollution and extreme temperatures on pulmonary circulation and the right heart, on the severity and outcomes of patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (PH), on the incidence of pulmonary embolism, and the prevalence and severity of diseases associated with PH. Furthermore, the downstream consequences of climate change impair health care systems' accessibility, which could pose unique obstacles in the case of PVD patients, who require a complex and sophisticated network of health interventions. Patients, caretakers and health care professionals should thus be included in the design of policies aimed at adaptation to and mitigation of current challenges, and prevention of further climate change. The purpose of this review is to summarize the available evidence concerning the impact of environmental pollution and climate change on the pulmonary circulation, and to propose measures at the individual, healthcare and community levels directed at protecting patients with PVD.

Early Pulmonary Fibrosis-like Changes in the Setting of Heat Exposure: DNA Damage and Cell Senescence

It is well known that extreme heat events happen frequently due to climate change. However, studies examining the direct health impacts of increased temperature and heat waves are lacking. Previous reports revealed that heatstroke induced acute lung injury and pulmonary dysfunction. This study aimed to investigate whether heat exposure induced lung fibrosis and to explore the underlying mechanisms. Male C57BL/6 mice were exposed to an ambient temperature of 39.5 ± 0.5 °C until their core temperature reached the maximum or heat exhaustion state. Lung fibrosis was observed in the lungs of heat-exposed mice, with extensive collagen deposition and the elevated expression of fibrosis molecules, including transforming growth factor-β1 (TGF-β1) and Fibronectin (Fn1) (p < 0.05). Moreover, epithelial-mesenchymal transition (EMT) occurred in response to heat exposure, evidenced by E-cadherin, an epithelial marker, which was downregulated, whereas markers of EMT, such as connective tissue growth factor (CTGF) and the zinc finger transcriptional repressor protein Slug, were upregulated in the heat-exposed lung tissues of mice (p < 0.05). Subsequently, cell senescence examination revealed that the levels of both senescence-associated β-galactosidase (SA-β-gal) staining and the cell cycle protein kinase inhibitor p21 were significantly elevated (p < 0.05). Mechanistically, the cGAS-STING signaling pathway evoked by DNA damage was activated in response to heat exposure (p < 0.05). In summary, we reported a new finding that heat exposure contributed to the development of early pulmonary fibrosis-like changes through the DNA damage-activated cGAS-STING pathway followed by cellular senescence.

Machine learning-based prediction of in-hospital mortality in patients with pneumonic chronic obstructive pulmonary disease exacerbations

OBJECTIVE

While linear regression and LASSO models have been established for predicting in-hospital mortality, there is currently no validated clinical prediction algorithm to predict in-hospital mortality for patients with chronic obstructive pulmonary disease (COPD) exacerbations using machine learning. Thus, we will evaluate the BAP-65 and CURB-65, and construct a novel prediction model using the random forest (RF) technique.

METHODS

A dataset of 1,418 patients with COPD exacerbations was collected. Age, gender, mental status, vital signs, and laboratory results were all taken into account for predictors. The categorical outcome variable was hospital-based mortality of people over 65 years. The dataset was divided randomly into a training dataset (70%) and a testing dataset (30%). We trained three prediction models, BAP-65, CURB-65, and the RF model, estimated the area under the receiver operating characteristic curve (AUROC) for the entire dataset. We also conducted a comparison of the AUROC values using the Delong test.

RESULTS

A total of 658 individuals with COPD acute exacerbations were enrolled. Our analysis using the receiver operating characteristic curve demonstrated that the RF model exhibited excellent performance, with an AUROC of 0.80 (95% confidence interval: 0.75-0.84). In comparison, the BAP-65 prediction model yielded an AUROC of 0.72 (0.68-0.75), while the CURB-65 prediction model achieved an AUROC of 0.69 (0.67-0.73).

CONCLUSIONS

The RF model demonstrated superior predictive capabilities than the BAP-65 and CURB-65 models in predicting in-hospital mortality. The results further highlighted significant factors for predicting in-hospital mortality, including blood eosinophil count, systolic blood pressure, and prior history of asthma.

Assessing heatwave effects on disabled persons in South Korea

This study investigated the risk of heatwaves for people with disabilities and other socioeconomic attributes using Health Care Bigdata in South Korea. The Health Care Bigdata provides detailed information on heat-related illness (HRI) patients in 2011-2020 from seven major cities. We employed the Distributed Lag Nonlinear Model (DLNM) to measure heat waves' relative risk. Our findings are four-fold. First, the relative risk (RR) of disabled people was 5.075 (95% confidence interval 4.476-5.674), significantly surpassing that of non-disabled people, 3.296 (2.517-4.075). Second, among various personal characteristics studied, disability influenced RR the most, exceeding impacts from elderly (4.457: 3.748-5.166), low-income (3.909: 3.004-4.813), and outdoor (4.052: 2.940-5.164). Third, the disabled young group (5.305: 4.414-6.195) was more vulnerable than the non-disabled elderly group (4.287: 3.576-4.999). Lastly, no significant difference in relative risk was observed between the mild (4.413: 3.855-4.971) and severe disabled groups (4.013: 3.121-4.905).

Heat and Cold Wave-Related Mortality Risk among United States Veterans with Chronic Obstructive Pulmonary Disease: A Case-Crossover Study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a heterogeneous pulmonary disease affecting 16 million Americans. Individuals with COPD are susceptible to environmental disturbances including heat and cold waves that can exacerbate disease symptoms.

OBJECTIVE

Our objective was to estimate heat and cold wave-associated mortality risks within a population diagnosed with a chronic respiratory disease.

METHODS

We collected individual level data with geocoded residential addresses from the Veterans Health Administration on 377,545 deceased patients with COPD (2016 to 2021). A time stratified case-crossover study was designed to estimate the incidence rate ratios (IRR) of heat and cold wave mortality risks using conditional logistic regression models examining lagged effects up to 7 d. Attributable risks (AR) were calculated for the lag day with the strongest association for heat and cold waves, respectively. Effect modification by age, gender, race, and ethnicity was also explored.

RESULTS

Heat waves had the strongest effect on all-cause mortality at lag day 0 [IRR: 1.04; 95% confidence interval (CI): 1.02, 1.06] with attenuated effects by lag day 1. The AR at lag day 0 was 651 (95% CI: 326, 975) per 100,000 veterans. The effect of cold waves steadily increased from lag day 2 and plateaued at lag day 4 (IRR: 1.04; 95% CI: 1.02, 1.07) with declining but still elevated effects over the remaining 7-d lag period. The AR at lag day 4 was 687 (95% CI: 344, 1,200) per 100,000 veterans. Differences in risk were also detected upon stratification by gender and race.

DISCUSSION

Our study demonstrated harmful associations between heat and cold waves among a high-risk population of veterans with COPD using individual level health data. Future research should emphasize using individual level data to better estimate the associations between extreme weather events and health outcomes for high-risk populations with chronic medical conditions. https://doi.org/10.1289/EHP13176.

High temperature exacerbates ozone-induced airway inflammation: Implication of airway microbiota and metabolites

Short-term exposure to ozone (O3) has been associated with airway inflammation. Given that high temperature (HT) accelerates O3 production, it is of significance to determine whether co-exposure to HT exacerbates O3-induced airway inflammation. The aim of this study was to examine the possible promotive effect of HT on O3-induced airway inflammation and underlying mechanisms. Forty-eight C57BL/6 N male mice were randomly divided into four groups: filtered air (control), O3, HT, and HT + O3 (co-exposure) groups. Mice in control and O3 groups were exposed to filtered air or 1 ppm O3 at 24 °C, respectively, while mice in HT and co-exposure groups were exposed to filtered air or 1 ppm O3 at 36 °C, respectively. The exposure scenario for four groups was 4 h/d for 5 consecutive days. Bronchoalveolar lavage fluids (BALF) were collected 24 h after the last exposure and subjected to examinations of oxidative stress and inflammation biomarkers, 16S rRNA sequencing, and metabolic profiling. Lung tissues were processed for H&E histological staining. The results showed that O3 inhalation triggered oxidative stress and inflammation in the airways, which was worsen by co-exposure to HT. Further studies revealed that co-exposure to HT strengthened O3-induced decline in Firmicutes and Allobaculum in airways. Moreover, co-exposure to HT promoted O3-induced airway metabolic disorder. Spearman correlation analysis revealed correlations among microbiota dysbiosis, metabolic disorder, oxidative stress and inflammation induced by co-exposure to HT and O3. Taken together, HT exposure aggravates O3-induced airway oxidative stress and inflammation, possibly through modulation of microbiota and metabolism of the airways.

A cross-sectional survey on the effects of ambient temperature and humidity on health outcomes in individuals with chronic respiratory disease

Rationale

Extremes of temperature and humidity are associated with adverse respiratory symptoms, reduced lung function, and increased exacerbations among individuals living with chronic obstructive pulmonary disease (COPD).

Objectives

To describe the reported effects of temperature and humidity extremes on the health outcomes, health status and physical activity (PA) in individuals living with COPD.

Methods

A cross-sectional self-reported survey collected the effects on health status (COPD Assessment Test [CAT]), PA, and health outcomes in 1) moderate/ideal (14 to 21°C, 30 to 50% relative humidity [RH]), 2) hot and humid (≥ 25°C, > 50% RH) and 3) cold and dry (≤ 5°C, < 30% RH) weather conditions. Participants were ≥ 40 years old with COPD or related chronic respiratory diseases (e.g., asthma, sleep apnea, interstitial lung disease, lung cancer) and residing in Canada for ≥ 1 year. Negative responders to weather extremes were a priori defined as having a change of ≥ 2 points in the CAT.

Main Results

Thirty-six participants responded; the mean age (SD) was 65 (11) years, and 23 (64%) were females. Compared to ideal conditions, 23 (66%) and 24 (69%) were negatively affected by cold/dry and hot/humid weather, respectively. Health status was significantly lower, and PA amount and difficulty level were reduced in hot/humid and cold/dry conditions compared with ideal conditions. The number of exacerbations in hot/humid was significantly higher compared to ideal conditions.

Conclusions

More participants were negatively affected by extremes of weather: health status worsened, PA decreased, and frequency of exacerbations was higher compared to ideal. Future prospective studies should directly and objectively investigate different combinations of extreme temperature and humidity levels on symptoms and PA to understand their long-term health outcomes.

Ambient temperature and seasonal variation in inpatient mortality from respiratory diseases: a retrospective observational study

Background

The seasonal fluctuation in mortality and hospital admissions from respiratory diseases, with a winter peak and a summer trough, is widely recognized in extratropical countries. However, little is known about the seasonality of inpatient mortality and the role of ambient temperature remains uncertain. We aimed to analyse the association between ambient temperature and in-hospital mortality from respiratory diseases in the provinces of Madrid and Barcelona, Spain.

Methods

We used data on daily hospitalisations, weather (ie, temperature and relative humidity) and air pollutants (ie, PM2.5, PM10, NO2 and O3) for the Spanish provinces of Madrid and Barcelona during 2006-2019. We applied a daily time-series quasi-Poisson regression in combination with distributed lag non-linear models (DLNM) to assess, on the one hand, the seasonal variation in fatal hospitalisations and the contribution of ambient temperature, and on the other hand, the day-to-day association between temperature and fatal hospital admissions. The analyses were stratified by sex, age and primary diagnostic of hospitalisation.

Findings

The study analysed 1 710 012 emergency hospital admissions for respiratory diseases (mean [SD] age, 60.4 [31.0] years; 44.2% women), from which 103 845 resulted in in-hospital death (81.4 [12.3] years; 45.1%). We found a strong seasonal fluctuation in in-hospital mortality from respiratory diseases. While hospital admissions were higher during the cold season, the maximum incidence of inpatient mortality was during the summer and was strongly related to high temperatures. When analysing the day-to-day association between temperature and in-hospital mortality, we only found an effect for high temperatures. The relative risk (RR) of fatal hospitalisation at the 99th percentile of the distribution of daily temperatures vs the minimum mortality temperature (MMT) was 1.395 (95% eCI: 1.211-1.606) in Madrid and 1.612 (1.379-1.885) in Barcelona. In terms of attributable burden, summer temperatures (June-September) were responsible for 16.2% (8.8-23.3) and 22.3% (15.4-29.2) of overall fatal hospitalisations from respiratory diseases in Madrid and Barcelona, respectively. Women were more vulnerable to heat than men, whereas the results by diagnostic of admission showed heat effects for acute bronchitis and bronchiolitis, pneumonia and respiratory failure.

Interpretation

Unless effective adaptation measures are taken in hospital facilities, climate warming could exacerbate the burden of inpatient mortality from respiratory diseases during the warm season.

Funding

European Research Council Consolidator Grant EARLY-ADAPT, European Research Council Proof-of-Concept Grants HHS-EWS and FORECAST-AIR.

Effects of air temperature on the risk of death from COPD in major microregions in Brazil: a time series study

OBJECTIVE

To evaluate the association between the risk of death from COPD and air temperature events in ten major Brazilian microregions.

METHODS

This was a time series analysis of daily COPD deaths and daily mean air temperatures between 1996 and 2017. Using distributed nonlinear lag models, we estimated the cumulative relative risks of COPD mortality for four temperature percentiles (representing moderate and extreme cold and heat events) in relation to a minimum mortality temperature, with a lag of 21 days, in each microregion.

RESULTS

Significant associations were found between extreme air temperature events and the risk of death from COPD in the southern and southeastern microregions in Brazil. There was an association of extreme cold and an increased mortality risk in the following microregions: 36% (95% CI, 1.12-1.65), in Porto Alegre; 27% (95% CI, 1.03-1.58), in Curitiba; and 34% (95% CI, 1.19-1.52), in São Paulo; whereas moderate cold was associated with an increased risk of 20% (95% CI, 1.01-1.41), 33% (95% CI, 1.09-1.62), and 24% (95% CI, 1.12-1.38) in the same microregions, respectively. There was an increased COPD mortality risk in the São Paulo and Rio de Janeiro microregions: 17% (95% CI, 1.05-1.31) and 12% (95% CI, 1,02-1,23), respectively, due to moderate heat, and 23% (95% CI, 1,09-1,38) and 32% (95% CI, 1,15-1,50) due to extreme heat.

CONCLUSIONS

Non-optimal air temperature events were associated with an increased risk of death from COPD in tropical and subtropical areas of Brazil.

The Impact of Heat Waves on Health Care Services in Low- or Middle-Income Countries: Protocol for a Systematic Review

BACKGROUND

Heat waves significantly impact ecosystems and human health, especially that of vulnerable populations, and are associated with increased morbidity and mortality. Besides being directly related to climate-sensitive health outcomes, heat waves have indirectly increased the burden on our health care systems. Although the existing literature examines the impact of heat waves and morbidity, past research has mostly been conducted in high-income countries (HICs), and studies on the impact of heat waves on morbidity in low- or middle-income countries (LMICs) are still scarce.

OBJECTIVE

This paper presents the protocol for a systematic review that aims to provide evidence of the impact of heat waves on health care services in LMICs.

METHODS

We will identify peer-reviewed studies from 3 online databases, including the Web of Science, PubMed, and SCOPUS, published from January 2002 to April 2023, using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Quality assessment will be conducted using the Navigation Guide checklist. Key search terms include heatwaves, extreme heat, hospitalization, outpatient visit, burden, health services, and morbidity.

RESULTS

This systematic review will provide insight into the impact of heat waves on health care services in LMICs, especially on emergency department visits, ambulance call-outs, hospital admissions, outpatient department visits, in-hospital mortality, and health care operational costs.

CONCLUSIONS

The results of this review are anticipated to help policymakers and key stakeholders obtain a better understanding of the impact of heat waves on health care services and prioritize investments to mitigate the effects of heat waves in LMICs. This entails creating a comprehensive heat wave plan and ensuring that adequate infrastructure, capacity, and human resources are allocated in the health care sector. These measures will undoubtedly contribute to the development of resilience in health care systems and hence protect the health and well-being of individuals and communities.

TRIAL REGISTRATION

PROSPERO CRD42022365471; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=365471.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/44702.

Impact of heat on emergency hospital admission in Texas: geographic and racial/ethnic disparities

BACKGROUND

Studies exploring the racial/ethnicity disparity of the impact of heat on hospital admission are notably limited, especially in Texas, a state with a diverse population and consistently ranking among the top ten U.S. states for heat-related deaths per capita from 2018 to 2020.

OBJECTIVE

Our objective is to determine the correlation between elevated temperatures and emergency hospital admissions for various causes and age groups across 12 Metropolitan Statistical Areas(MSAs) in Texas. Additionally, we aim to investigate health inequalities in the five largest MSAs in Texas between 2004 and 2013.

METHODS

We used MSA-level hospital admission and weather data to estimate the relationship between heat and emergency hospital admissions. We applied a Generalized Additive Model and random effects meta-analysis to calculate MSA-specific associations and overall correlation, repeating the analysis for age groups and specific causes of admission. We also investigated health disparities across racial and ethnic groups and performed a sensitivity analysis.

RESULTS

The results showed that a 1 °C increase in temperature was associated with a 0.50% (95% CI [0.38%, 0.63%]) increase in all-cause emergency hospital admissions. Heat's impact on hospital admissions varied among age groups and causes, with children under 6 years showing the highest effect estimate (0.64% (95% CI [0.32%,0.96%])). Statistically significant associations were found for Cardiovascular Diseases (0.27% (95% CI [0.07%,0.47%])), Ischemic Heart Diseases (0.53% (95% CI [0.15%,0.92%])), Pneumonia (0.70% (95% CI [0.25%,1.16%])), and Respiratory Diseases (0.67% (95% CI [0.18%,1.17%])). Health disparities were found among racial and ethnic groups in the five largest MSAs.

IMPACT STATEMENT

Studies exploring the impact of heat on hospital admission in Texas are notably limited. Our research provided a comprehensive examination of the connection between heat and emergency hospital admissions throughout Texas. Furthermore, we are the first to examine racial/ethnic disparities, identifying African American and Hispanic groups as disproportionately affected. These insights provide valuable insights for policymakers to allocate resources and implement strategies to mitigate the negative consequences of rising temperatures.

Acute and chronic impacts of heat stress on planetary health

Heat waves are increasing in intensity, frequency, and duration causing significant heat stress in all living organisms. Heat stress has multiple negative effects on plants affecting photosynthesis, respiration, growth, development, and reproduction. It also impacts animals leading to physiological and behavioral alterations, such as reduced caloric intake, increased water intake, and decreased reproduction and growth. In humans, epidemiological studies have shown that heat waves are associated with increased morbidity and mortality. There are many biological effects of heat stress (structural changes, enzyme function disruption, damage through reactive oxygen or nitrogen species). While plants and animals can mitigate some of these effects through adaptive mechanisms such as the generation of heat shock proteins, antioxidants, stress granules, and others, these mechanisms may likely be inadequate with further global warming. This review summarizes the effects of heat stress on plants and animals and the adaptative mechanisms that have evolved to counteract this stress.

Does choice of outdoor heat metric affect heat-related epidemiologic analyses in the US Medicare population?

Outdoor air temperature is associated with increased morbidity and mortality. Other thermal indices theoretically confer greater physiological relevance by incorporating additional meteorological variables. However, the optimal metric for predicting excess deaths or hospitalizations owing to extreme heat among US Medicare beneficiaries remains unknown.

Methods

We calculated daily maximum, minimum, and mean outdoor air temperature (T), heat index (HI), wet-bulb globe temperature (WBGT), and Universal Thermal Climate Index (UTCI) for populous US counties and linked estimates with daily all-cause mortality and heat-related hospitalizations among Medicare beneficiaries (2006-2016). We fit distributed-lag nonlinear models for each metric and compared relative risks (RRs) at the 99th percentile.

Results

Across all heat metrics, extreme heat was statistically significantly associated with elevated risks of morbidity and mortality. Associations were more pronounced for maximum daily values versus the corresponding minimum for the same metric. The starkest example was between HImax (RR = 1.14; 95% confidence interval [CI] = 1.12, 1.15) and HImin (RR = 1.10; 95% CI = 1.09, 1.11) for hospitalizations. When comparing RRs across heat metrics, we found no statistically significant differences within the minimum and maximum heat values (i.e., no significant differences between Tmax/HImax/WBGTmax/UTCImax or between Tmin/HImin/WBGTmin/UTCImin). We found similar relationships across the National Climate Assessment regions.

Conclusion

Among Medicare beneficiaries in populous US counties, daily maximum and mean values of outdoor heat are associated with greater RRs of heat-related morbidity and all-cause mortality versus minimum values of the same metric. The choice of heat metric (e.g., temperature versus HI) does not appear to substantively affect risk calculations in this population.

Burden of chronic obstructive pulmonary disease attributable to non-optimal temperature from 1990 to 2019: a systematic analysis from the Global Burden of Disease Study 2019

Chronic obstructive pulmonary disease (COPD) has been the third leading cause of death worldwide. As the traditional risk factors (like smoking and ambient air pollution) on the burden of COPD being well characterized, the burden of COPD due to non-optimal temperature has been widely concerned. In this study, we extracted the relevant burden data of COPD attributable to non-optimal temperature from GBD 2019 and adopted estimated annual percent changes, Gaussian process regression (GPR), and age-period-cohort model to evaluate the spatiotemporal patterns, relationships with socio-demographic level, and the independent effects of age, period and cohort from 1990 to 2019. In brief, the global COPD burden attributable to non-optimal temperatures showed declining trends but was still more severe in the elderly, males, Asia, and regions with low socio-demographic index (SDI). And cold had a greater burden than heat. The inverted U-shape is expected for the relationship between SDI and the burden of COPD caused by non-optimal temperatures according to the GPR model, with the inflection point around SDI 0.45. Besides, the improvements were observed in period and cohort effects but were relatively limited in low and low-middle SDI regions. Public health managers should execute more targeted programs to lessen this burden predominantly among lower SDI countries.

Association of Temperature Thresholds with Heat Illness- and Cardiorespiratory-Related Emergency Visits during Summer Months in Alaska

BACKGROUND

Recent record-breaking hot temperatures in Alaska have raised concerns about the potential human health implications of heat exposure among this unacclimated population.

OBJECTIVES

We estimated cardiorespiratory morbidity associated with days above summer (June-August) heat index (HI, apparent temperature) thresholds in three major population centers (Anchorage, Fairbanks, and the Matanuska-Susitna Valley) for the years 2015-2019.

METHODS

We implemented time-stratified case-crossover analyses of emergency department (ED) visits for International Classification of Diseases, 10^th Revision codes indicative of heat illness and major cardiorespiratory diagnostic codes using data from the Alaska Health Facilities Data Reporting Program. Using conditional logistic regression models, we tested maximum hourly HI temperature thresholds between 21.1°C (70°F) and 30°C (86°F) for a single day, 2 consecutive days, and the absolute number of previous consecutive days above the threshold, adjusting for the daily average concentration of particulate matter ≤2.5μg.

RESULTS

There were increased odds of ED visits for heat illness above a HI threshold as low as 21.1°C (70°F) [odds ratio (OR)=13.84; 95% confidence interval (CI): 4.05, 47.29], and this increased risk continued for up to 4 d (OR=2.43; 95% CI: 1.15, 5.10). Asthma and pneumonia were the only respiratory outcomes positively associated with the HI: ED visits for both were highest the day after a heat event (Asthma: HI>27°C(80°F) OR=1.18; 95% CI: 1.00, 1.39; Pneumonia: HI>28°C(82°F) OR=1.40; 95% CI: 1.06, 1.84). There was a decreased odds of bronchitis-related ED visits when the HI was above thresholds of 21.1-28°C (70-82°F) across all lag days. We found stronger effects for ischemia and myocardial infarction (MI) than for respiratory outcomes. Multiple days of warm weather were associated with an increased risk of health impacts. For each additional preceding day above a HI of 22°C (72°F), the odds of ED visits related to ischemia increased 6% (95% CI: 1%, 12%); for each additional preceding day above a HI of 21.1°C (70°F), the odds of ED visits related to MI increased 7% (95% CI: 1%, 14%).

DISCUSSION

This study demonstrates the importance of planning for extreme heat events and developing local guidance for heat warnings, even in areas with historically mild summertime climates. https://doi.org/10.1289/EHP11363.

Hospital admission tendencies caused by day-to-day temperature changes during summer: a case study for the city of Novi Sad (Serbia)

Increased temperature risk in cities threatens the health and well-being of urban population and is fueled by climate change and intensive urbanization. Consequently, further steps must be taken for assessing temperature conditions in cities and their association with public health, in order to improve public health prevention at local or regional level. This study contributes to solving the problems by analyzing the connection between extreme temperatures and the tendencies of all-cause hospital admissions. The analyses used (a) 1-h air temperature data, and (b) daily data of all-cause hospital admissions. The datasets include the summer period (June, July, August) for the years 2016 and 2017. We tested the effects of two temperature indices, day-to-day change in maximum temperature - T_max,c and daily temperature range - T_r, with all-cause hospital admission subgroups, such as all-cause cases - H_a, hospital admissions in the population below 65 - H_a<65, and hospital admissions in the population aged 65 and over - H_a≥65. The results show the highest values of H_a when T_max,c is between 6 and 10 °C. Therefore, more intensive hospital admissions can be expected when T_max increases from day-to-day (positive values of T_max,c), and it is more visible for H_a and H_a<65 (1 °C = 1% increase in hospital admissions). Also, T_r values between 10 °C and 14 °C cause an increase in the number of hospital admissions, and it is more noticeable for H_a≥65.

Warm-season temperatures and emergency department visits among children with health insurance

High ambient temperatures have become more likely due to climate change and are linked to higher rates of heat-related illness, respiratory and cardiovascular diseases, mental health disorders, and other diseases. To date, far fewer studies have examined the effects of high temperatures on children versus adults, and studies including children have seldom been conducted on a national scale. Compared to adults, children have behavioral and physiological differences that may give them differential heat vulnerability. We acquired medical claims data from a large database of commercially insured US children aged 0-17 from May to September (warm-season) 2016-2019. Daily maximum ambient temperature and daily mean relative humidity estimates were aggregated to the county level using the Parameter-elevation Relationships on Independent Slopes dataset, and extreme heat was defined as the 95th percentile of the county-specific daily maximum temperature distribution. Using a case-crossover design and temperature lags 0-5 days, we estimated the associations between extreme heat and cause-specific emergency department visits (ED) in children aged <18 years, using the median county-specific daily maximum temperature distribution as the reference. Approximately 1.2 million ED visits in children from 2489 US counties were available during the study period. The 95th percentile of warm-season temperatures ranged from 71 °F to 112 °F (21.7 °C to 44.4 °C). Comparing 95th to the 50th percentile, extreme heat was associated with higher rates of ED visits for heat-related illness; endocrine, nutritional and metabolic diseases; and otitis media and externa, but not for all-cause admissions. Subgroup analyses suggested differences by age, with extreme heat positively associated with heat-related illness for both the 6-12 year (odds ratio [OR]: 1.34, 95% confidence interval [CI]: 1.16, 1.56) and 13-17 year age groups (OR: 1.55, 95% CI: 1.37, 1.76). Among children with health insurance across the US, days of extreme heat were associated with higher rates of healthcare utilization. These results highlight the importance of individual and population-level actions to protect children and adolescents from extreme heat, particularly in the context of continued climate change.

Geographic and demographic variation in worry about extreme heat and COVID-19 risk in summer 2020

Extreme heat is a major health hazard that is exacerbated by ongoing human-caused climate change. However, how populations perceive the risks of heat in the context of other hazards like COVID-19, and how perceptions vary geographically, are not well understood. Here we present spatially explicit estimates of worry among the U.S. public about the risks of heat and COVID-19 during the summer of 2020, using nationally representative survey data and a multilevel regression and poststratification (MRP) model. Worry about extreme heat and COVID-19 varies both across states and across demographic groups, in ways that reflect disparities in the impact of each risk. Black or African American and Hispanic or Latino populations, who face greater health impacts from both COVID-19 and extreme heat due to institutional and societal inequalities, also tend to be much more worried about both risks than white, non-Hispanic populations. Worry about heat and COVID-19 were correlated at the individual and population level, and patterns tended to be related to underlying external factors associated with the risk environment. In the face of a changing climate there is an urgent need to address disparities in heat risk and develop responses that ensure the most at-risk populations are protected.

Short-term associations between warm-season ambient temperature and emergency department visits for Alzheimer's disease and related dementia in five US states

BACKGROUND

Ambient temperatures are projected to increase in the future due to climate change. Alzheimer's disease (AD) and Alzheimer's disease-related dementia (ADRD) affect millions of individuals and represent substantial health burdens in the US. High temperature may be a risk factor for AD/ADRD outcomes with several recent studies reporting associations between temperature and AD mortality. However, the link between heat and AD morbidity is poorly understood.

METHODS

We examined short-term associations between warm-season daily ambient temperature and AD/ADRD emergency department (ED) visits for individuals aged 45 years or above during the warm season (May to October) for up to 14 years (2005-2018) in five US states: California, Missouri, North Carolina, New Jersey, and New York. Daily ZIP code-level maximum, average and minimum temperature exposures were derived from 1 km gridded Daymet products. Associations are assessed using a time-stratified case-crossover design using conditional logistic regression.

RESULTS

We found consistent positive short-term effects of ambient temperature among 3.4 million AD/ADRD ED visits across five states. An increase of the 3-day cumulative temperature exposure of daily average temperature from the 50th to the 95th percentile was associated with a pooled odds ratio of 1.042 (95% CI: 1.034, 1.051) for AD/ADRD ED visits. We observed evidence of the association being stronger for patients 65-74 years of age and for ED visits that led to hospital admissions. Temperature associations were also stronger among AD/ADRD ED visits compared to ED visits for other reasons, particularly among patients aged 65-74 years.

CONCLUSION

People with AD/ADRD may represent a vulnerable population affected by short-term exposure to high temperature. Our results support the development of targeted strategies to reduce heat-related AD/ADRD morbidity in the context of global warming.

Asthma triggered by extreme temperatures: From epidemiological evidence to biological plausibility

BACKGROUND

There is rapidly growing evidence indicating that extreme temperature is a crucial trigger and potential activator of asthma; however, the effects of extreme temperature on asthma are inconsistently reported and the its potential mechanisms remain undefined.

OBJECTIVES

This review aims to estimate the impacts of extreme heat, extreme cold, and temperature variations on asthma by systematically summarizing the existing studies from epidemiological evidence to biological plausibility.

METHODS

We conducted a systematic search in PubMed, Embase, and Web of Science from inception to June 30, 2022, and we retrieved articles of epidemiology and biological studies which assessed associations between extreme temperatures and asthma. This protocol was registered with PROSPERO (CRD42021273613).

RESULTS

From 12,435 identified records, 111 eligible studies were included in the qualitative synthesis, and 37 articles were included in the meta-analysis (20 for extreme heat, 16 for extreme cold, and 15 for temperature variations). For epidemiological evidence, we found that the synergistic effects of extreme temperatures, indoor/outdoor environments, and individual vulnerabilities are important triggers for asthma attacks, especially when there is extreme heat or cold. Meta-analysis further confirmed the associations, and the pooled relative risks for asthma attacks in extreme heat and extreme cold were 1.07 (95%CI: 1.03-1.12) and 1.20 (95%CI: 1.12-1.29), respectively. Additionally, this review discussed the potential inflammatory mechanisms behind the associations between extreme temperatures and asthma exacerbation, and highlighted the regulatory role of immunological pathways and transient receptor potential ion channels in asthma triggered by extreme temperatures.

CONCLUSIONS

We concluded that both extreme heat and cold could significantly increase the risk of asthma. Additionally, we proposed a potential mechanistic framework, which is important for understanding the disease pathogenesis that uncovers the complex mechanisms of asthma triggered by extreme temperatures and protects the sensitive individuals from impacts of extreme weather events and climate change.

Potential effect of heat adaptation on association between number of heatstroke patients transported by ambulance and wet bulb globe temperature in Japan

This study analyzed the association between heatstroke incidence and daily maximum wet bulb globe temperature (WBGT) for all 47 prefectures in Japan by age group and severity using time-series analysis, controlling for confounders, such as seasonality and long-term trends. With the obtained association, the relative risk between the reference WBGT (defined as the value at which heatstroke starts to increase) and the daily maximum WBGT at 30 °C (RR_wbgt30) of each prefecture were calculated. For the heatstroke data, the daily number of heatstroke patients transported by ambulance at the prefecture level, provided by the Fire and Disaster Management Agency, was utilized. The analysis was conducted for age groups of 7-17 y, 18-64 y, and ≥65 y, and for severity of Deceased, Severe, Moderate (combined as DSM), and Mild. The analysis period was set from May 1 to September 30, 2015-2019. Finally, the correlation between RR_wbgt30 and the average daily maximum WBGT during the analysis period (aveWBGTms) of each prefecture was analyzed to examine the regionality of heatstroke incidence. The result showed that RR_wbgt30 is negatively correlated with aveWBGTms for the age group 18-64 y and ≥65 y (except for the age group 7-17 y) and for severity. The natural logarithm of the RR_wbgt30 of all 47 prefectures ranged from 2.0 to 8.2 for the age group 7-17 y, 1.1 to 4.0 for the age group 18-64 y, 1.8 to 6.0 for the age group ≥65 y, and 1.0 to 3.6 for DSM, and 0.9 to 4.0 for Mild. This regionality can be attributed to the effects of heat adaptation, where people in hotter regions are accustomed to implementing measures against hot environments and are more heat acclimatized than people in cooler regions.

How neighborhood environment modified the effects of power outages on multiple health outcomes in New York state?

Background

Although power outage (PO) is one of the most important consequences of increasing weather extremes and the health impact of POs has been reported previously, studies on the neighborhood environment underlying the population vulnerability in such situations are limited. This study aimed to identify dominant neighborhood environmental predictors which modified the impact of POs on multiple health outcomes in New York State.

Methods

We applied a two-stage approach. In the first stage, we used time series analysis to determine the impact of POs (versus non-PO periods) on multiple health outcomes in each power operating division in New York State, 2001-2013. In the second stage, we classified divisions as risk-elevated and non-elevated, then developed predictive models for the elevation status based on 36 neighborhood environmental factors using random forest and gradient boosted trees.

Results

Consistent across different outcomes, we found predictors representing greater urbanization, particularly, the proportion of residents having access to public transportation (importance ranging from 4.9-15.6%), population density (3.3-16.1%), per capita income (2.3-10.7%), and the density of public infrastructure (0.8-8.5%), were associated with a higher possibility of risk elevation following power outages. Additionally, the percent of minority (-6.3-27.9%) and those with limited English (2.2-8.1%), the percent of sandy soil (6.5-11.8%), and average soil temperature (3.0-15.7%) were also dominant predictors for multiple outcomes. Spatial hotspots of vulnerability generally were located surrounding New York City and in the northwest, the pattern of which was consistent with socioeconomic status.

Conclusion

Population vulnerability during power outages was dominated by neighborhood environmental factors representing greater urbanization.

Neighborhood environmental factors linked to hospitalizations of older people for viral lower respiratory tract infections in Spain: a case-crossover study

BACKGROUND

Lower respiratory tract viral infection (LRTI) is a significant cause of morbidity-mortality in older people worldwide. We analyzed the association between short-term exposure to environmental factors (climatic factors and outdoor air pollution) and hospital admissions with a viral LRTI diagnosis in older adults.

METHODS

We conducted a bidirectional case-crossover study in 6367 patients over 65 years of age with viral LRTI and residential zip code in the Spanish Minimum Basic Data Set. Spain's State Meteorological Agency was the source of environmental data. Associations were assessed using conditional logistic regression. P-values were corrected for false discovery rate (q-values).

RESULTS

Almost all were hospital emergency admissions (98.13%), 18.64% were admitted to the intensive care unit (ICU), and 7.44% died. The most frequent clinical discharge diagnosis was influenza (90.25%). LRTI hospital admissions were more frequent when there were lower values of temperature and O₃ and higher values of relative humidity and NO₂. The regression analysis adjusted by temperatures and relative humidity showed higher concentrations at the hospital admission for NO₂ [compared to the lag time of 1-week (q-value< 0.001) and 2-weeks (q-value< 0.001)] and O₃ [compared to the lag time of 3-days (q-value< 0.001), 1-week (q-value< 0.001), and 2-weeks (q-value< 0.001)] were related to a higher odds of hospital admissions due to viral LRTI. Moreover, higher concentrations of PM₁₀ at the lag time of 1-week (q-value = 0.023) and 2-weeks (q-value = 0.002), and CO at the lag time of 3-days (q-value = 0.023), 1-week (q-value< 0.001) and 2-weeks (q-value< 0.001)], compared to the day of hospitalization, were related to a higher chances of hospital admissions with viral LRTI.

CONCLUSION

Unfavorable environmental factors (low temperatures, high relative humidity, and high concentrations of NO₂, O₃, PM₁₀, and CO) increased the odds of hospital admissions with viral LRTI among older people, indicating they are potentially vulnerable to these environmental factors.

Ambient heat exposure and COPD hospitalisations in England: a nationwide case-crossover study during 2007-2018

BACKGROUND

There is emerging evidence suggesting a link between ambient heat exposure and chronic obstructive pulmonary disease (COPD) hospitalisations. Individual and contextual characteristics can affect population vulnerabilities to COPD hospitalisation due to heat exposure. This study quantifies the effect of ambient heat on COPD hospitalisations and examines population vulnerabilities by age, sex and contextual characteristics.

METHODS

Individual data on COPD hospitalisation at high geographical resolution (postcodes) during 2007-2018 in England was retrieved from the small area health statistics unit. Maximum temperature at 1 km ×1 km resolution was available from the UK Met Office. We employed a case-crossover study design and fitted Bayesian conditional Poisson regression models. We adjusted for relative humidity and national holidays, and examined effect modification by age, sex, green space, average temperature, deprivation and urbanicity.

RESULTS

After accounting for confounding, we found 1.47% (95% Credible Interval (CrI) 1.19% to 1.73%) increase in the hospitalisation risk for every 1°C increase in temperatures above 23.2°C (lags 0-2 days). We reported weak evidence of an effect modification by sex and age. We found a strong spatial determinant of the COPD hospitalisation risk due to heat exposure, which was alleviated when we accounted for contextual characteristics. 1851 (95% CrI 1 576 to 2 079) COPD hospitalisations were associated with temperatures above 23.2°C annually.

CONCLUSION

Our study suggests that resources should be allocated to support the public health systems, for instance, through developing or expanding heat-health alerts, to challenge the increasing future heat-related COPD hospitalisation burden.

Lifestyle and environmental factors may induce airway and systemic inflammation in firefighters

Health status depends on multiple genetic and non-genetic factors. Nonheritable factors (such as lifestyle and environmental factors) have stronger impact on immune responses than genetic factors. Firefighters work is associated with exposure to air pollution and heat stress, as well as: extreme physical effort, mental stress, or a changed circadian rhythm, among others. All these factors can contribute to both, short-term and long-term impairment of the physical and mental health of firefighters. Increased levels of some inflammatory markers, such as pro-inflammatory cytokines or C-reactive protein (CRP) have been observed in firefighters, which can lead to local, acute inflammation that promotes a systemic inflammatory response. It is worth emphasizing that inflammation is one of the main hallmarks of cancer and also plays a key role in the development of cardiovascular and respiratory diseases. This article presents possible causes of the development of an inflammatory reaction in firefighters, with particular emphasis on airway inflammation caused by smoke exposure.

[Adaptation to extreme weather event is key to protection of human health]

Extreme weather events (EWE) are the most direct and visible example of how climate change threatens human health. Notwithstanding the diversity of EWEs, they all have recurrent impacts on mortality, morbidity and mental health. These impacts largely depend on exposure conditions, on the response measures implemented, and on socio-economic determinants. Forest fires and heat waves are the EWEs in all likelihood presenting the highest risks for respiratory health, and they are likely to rapidly evolve over the coming years. Since 2004, more than 10,000 excess deaths have been recorded during heat waves in France, 76 % of them after 2015. Pronounced synergies between extreme heat and air pollution are now documented in the literature. In addition to appropriate behaviours and medical care during EWEs, adaptation must now focus on long-term interventions, the objectives being to reduce exposure, to improve the quality of our environment and to reinforce social ties.

Impact of ambient temperature on hospital admissions for respiratory diseases in suburban rural villages in northwest China

Extreme temperature is strongly associated with human health, but few studies are available for the effects of extreme temperatures on respiratory disease (RD) in rural villages in Jiuquan, China over 2018-2019. In this study, we evaluate the effect of daily mean temperature on RD hospitalizations in suburban rural villages. A distribution lag non-linear model was constructed to analyze the relationship between the temperature and the daily risk of RD hospitalizations; and stratified analysis by sex and age group was performed. The effect of daily mean temperature on RD hospitalizations was non-linear and lagging. With a reference 25th percentile of temperature (-1.8 °C), exposure to extremely low temperature (-15.8 °C, 1st percentile), or moderate low temperature (-8.3 °C, 10th percentile) were associated with 1.396 (95% CI: 1.251, 1.558) and 1.216 (95% CI: 1.180, 1.253) increased risks of RD hospitalizations over lag 0-21 days. For RD morbidity, the effects of moderate high temperature (90th percentile of temperature, 22.5 °C) appeared at on the exposed day (lag 0), with the largest hot effect (RR 1.008, 95% CI 1.001, 1.020), while the effects of extremely high temperature (99th percentile of temperature, 27.0 °C) were insignificant. The effect of ambient temperature varied with gender and age. Both cold and high temperatures have more serious influence on males than females. In contrast, the elderly (age ≥ 65) seemed to be more sensitive in extremely low temperature (RR = 3.471; 95% CI, 2.183, 5.518; lag 0-21). The effect of moderate high temperature on the < 65 years group appeared for the first time at lag 0 (RR = 1.012; 95% CI, 1.001, 1.029). Both high temperature and low temperature increased the RD hospitalization risk; the harmful effect and duration of low temperature were greater than that of high temperature; the ≥ 65-year group and male were more sensitive to low temperature.

Climate Change and Respiratory Diseases: Relationship between SARS and Climatic Parameters and Impact of Climate Change on the Geographical Distribution of SARS in Iran

Climate change affects human health, and severe acute respiratory syndrome (SARS) incidence is one of the health impacts of climate change. This study is a retrospective cohort study. Data have been collected from the Iranian Ministry of Health and Medical Education between 17 February 2016 and17 February 2018. The Neural Network Model has been used to predict SARS infection. Based on the results of the multivariate Poisson regression and the analysis of the coexistence of the variables, the minimum daily temperature was positively associated with the risk of SARS in men and women. The risk of SARS has increased in women and men with increasing daily rainfall. According to the result, by changes in bioclimatic parameters, the number of SARS patients will be increased in cities of Iran. Our study has shown a significant relationship between SARS and the climatic variables by the type of climate and gender. The estimates suggest that hospital admissions for climate-related respiratory diseases in Iran will increase by 36% from 2020 to 2050. This study demonstrates one of the health impacts of climate change. Policymakers can control the risks of climate change by mitigation and adaptation strategists.

Hospitalization Costs of Respiratory Diseases Attributable to Temperature in Australia and Projections for Future Costs in the 2030s and 2050s under Climate Change

This study aimed to estimate respiratory disease hospitalization costs attributable to ambient temperatures and to estimate the future hospitalization costs in Australia. The associations between daily hospitalization costs for respiratory diseases and temperatures in Sydney and Perth over the study period of 2010-2016 were analyzed using distributed non-linear lag models. Future hospitalization costs were estimated based on three predicted climate change scenarios-RCP2.6, RCP4.5 and RCP8.5. The estimated respiratory disease hospitalization costs attributable to ambient temperatures increased from 493.2 million Australian dollars (AUD) in the 2010s to more than AUD 700 million in 2050s in Sydney and from AUD 98.0 million to about AUD 150 million in Perth. The current cold attributable fraction in Sydney (23.7%) and Perth (11.2%) is estimated to decline by the middle of this century to (18.1-20.1%) and (5.1-6.6%), respectively, while the heat-attributable fraction for respiratory disease is expected to gradually increase from 2.6% up to 5.5% in Perth. Limitations of this study should be noted, such as lacking information on individual-level exposures, local air pollution levels, and other behavioral risks, which is common in such ecological studies. Nonetheless, this study found both cold and hot temperatures increased the overall hospitalization costs for respiratory diseases, although the attributable fractions varied. The largest contributor was cold temperatures. While respiratory disease hospitalization costs will increase in the future, climate change may result in a decrease in the cold attributable fraction and an increase in the heat attributable fraction, depending on the location.

The Association between Weather and Emergency Department Visitation for Diabetes in Roanoke, Virginia

Diabetes mellitus imposes a significant and increasing health burden on the US population. Our objective is to determine if weather is related to daily variations in emergency department (ED) visits for diabetes mellitus in Roanoke, Virginia. A time series of daily ED visits for diabetes mellitus at the Carilion Clinic in southwestern Virginia is associated with daily minimum temperature from 2010-2017. Associations between ED visits (through a 14-day lag period) and temperature are examined using generalized additive models and distributed lag nonlinear models. Heat and cold waves are identified at low and high thresholds, and ED visitation during these events is compared to prior control periods using a time-stratified case crossover approach. ED visits for diabetes exhibit a U-shaped relationship with temperature, with a higher relative risk (RR) during cold events (RR = 1.05) vs. warm events (RR = 1.02). When minimum temperatures are below freezing, ED visitation peaks starting 2 days afterward, with RRs approaching 1.04. The RR on warm days (minimum temperature > 10 °C) approaches 1.02 but peaks on the day of or the day following the elevated temperatures. Cold waves increase the odds of ED visits by up to 11% (p = 0.01), whereas heat waves exhibit no significant effect (p = 0.07). The increasing health burden linked to diabetes requires new research on environmental factors that might exacerbate related illness. When examined in the context of climate change impacts on local weather variations, these kinds of linkages between environment and disease can aid in facility staffing and public health messaging during extreme weather events.

A Longitudinal Study on the Impact of Indoor Temperature on Heat-Related Symptoms in Older Adults Living in Non-Air-Conditioned Households

BACKGROUND

Both chronic and acute heat result in a substantial health burden globally, causing particular concern for at-risk populations, such as older adults. Outdoor temperatures are often assessed as the exposure and are used for heat warning systems despite individuals spending most of their time indoors. Many studies use ecological designs, with death or hospitalizations rates. Individual-level outcomes that are directly related to heat-symptoms should also be considered to refine prevention efforts.

OBJECTIVES

In this longitudinal study, we assessed the association between indoor temperature and proximal symptoms in individuals ≥60 years of age living in non-air-conditioned households in Montérégie, Quebec, during the 2017-2018 summer months.

METHODS

We gathered continuously measured indoor temperature and humidity from HOBO sensors and repeated health-related questionnaires about health-related symptoms administered across three periods of increasing outdoor temperatures, where the reference measurement (T1) occurred during a cool period with a target temperature of 18-22°C and two measurements (T2 and T3) occurred during warmer periods with target temperatures of 28-30°C and 30-33°C, respectively. We used generalized estimating equations with Poisson regression models and estimated risk ratios (RRs) between temperature, humidity, and each heat-related symptom.

RESULTS

Participants (n=277) had an average age (mean±standard deviation) of 72.8±7.02y. Higher indoor temperatures were associated with increased risk of dry mouth (T3 RR=2.5; 95% CI: 1.8, 3.5), fatigue (RR=2.3; 95% CI: 1.8, 3.0), thirst (RR=3.4; 95% CI: 2.5, 4.5), less frequent urination (RR=3.7; 95% CI: 1.8, 7.3), and trouble sleeping (RR=2.2; 95% CI: 1.6, 3.2) compared with T1. We identified a nonlinear relationship with indoor temperatures across most symptoms of interest.

DISCUSSION

This study identified that increasing indoor temperatures were associated with various health symptoms. By considering the prevalence of these early stage outcomes and indoor temperature exposures, adaptation strategies may be improved to minimize the burden of heat among vulnerable communities. https://doi.org/10.1289/EHP10291.

Non-optimum ambient temperature may decrease pulmonary function: A longitudinal study with intensively repeated measurements among asthmatic adult patients in 25 Chinese cities

BACKGROUND

Non-optimum ambient temperature has not been widely perceived as an important environmental risk factor for asthma, and the association between ambient temperature and pulmonary function is rarely explored. Our study aimed to investigate the associations between non-optimum ambient temperature and pulmonary function among asthmatic adult patients.

METHODS

We performed a longitudinal study among 4,992 eligible adult asthmatic patients in 25 cities of China from 2017 to 2020. The patients were required to complete pulmonary function test every day in the morning and evening. Linear mixed-effects models and distributed lag non-linear models were used to evaluate the associations between ambient temperature and pulmonary function.

RESULTS

We evaluated 298,396 records of pulmonary function tests. We found inversely J-shaped exposure-response relationship curves for ambient temperature and pulmonary function. The effects of extreme low temperature occurred at lag 0 h and vanished at lag 72 h (almost 3 days). Compared with referent temperature (29.5 °C), extreme low temperature (-9.4 °C) was associated with decreases of 60.4 mL in FEV₁, 299.7 mL/s in PEF, and 101.5 mL in FVC. Extreme high temperature (34.2 °C) was associated with decreases of 26.0 mL in FEV₁, 35.8 mL/s in PEF, and 23.4 mL in FVC. Patients of male, overweight, and elder ages were vulnerable populations, and cold effects were more prominent in the south and in areas without central heating.

CONCLUSIONS

Both extreme low and high ambient temperatures were associated with decreased pulmonary function in adult asthmatic patients. The effect could last for almost 3 days and low temperature was more harmful.

Temperature variability associations with cardiovascular and respiratory emergency department visits in Dhaka, Bangladesh

BACKGROUND

Greenhouse gas emissions are changing the Earth's climate, most directly by modifying temperatures and temperature variability (TV). Residents of low- and middle-income countries (LMICs) are likely more adversely affected, due to lack of air conditioning to compensate. To date, there is no local epidemiological evidence documenting the cardio-respiratory health effects of TV in Dhaka, Bangladesh, one of the most climate change vulnerable cities in the world.

OBJECTIVES

We assessed short-term TV associations with daily cardiovascular disease (CVD) and respiratory emergency department (ED) visits, as well as effect modification by age and season.

METHODS

TV was calculated from the standard deviations of the daily minimum and maximum temperatures over exposure days. Time-series regression modeling was applied to daily ED visits for respiratory and CVD from January 2014 through December 2017. TV effect sizes were estimated after controlling for long-term trends and seasonality, day-of-week, holidays, and daily mean relative humidity and ambient temperature.

RESULTS

A 1 °C increase in TV was associated with a 1.00% (95 %CI: 0.05%, 1.96%) increase in CVD ED visits at lag 0-1 days (TV0-1) and a 2.77% (95 %CI: 0.24%, 5.20%) increase in respiratory ED visits at lag 0-7 days (TV0-7). TV-CVD associations were larger in the monsoon and cold seasons. Respiratory ED visit associations varied by age, with older adults more affected by the TV across all seasons. A 1 °C increase in TV at lag 0-7 days (TV0-7) was associated with a 7.45% (95 %CI: 2.33%, 12.57%) increase in respiratory ED visits among patients above 50 years of age.

CONCLUSION

This study provided novel and important evidence that cardio-pulmonary health in Dhaka is adversely affected year-round by day-to-day increases in TV, especially among older adults. TV is a key factor that should be considered in evaluating the potential human health impacts of climate change induced temperature changes.

Review of Ground-Level Ozone Impact in Respiratory Health Deterioration for the Past Two Decades

Background: Ground-level ozone has been gaining notoriety with increasing evidence of its nefarious effects on health, especially respiratory diseases. Where do we stand on the solidity of this data and is there room for improvement? Objectives: Evaluate this evidence for incongruities or heterogeneity in this field of research. How is the exposure assessment conducted, where does Portugal stand in this field, and what can be improved? Health deterioration concerning asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS) are analysed. Methods: A review of 1735 studies was conducted through PubMed and Google Scholar engines for the past two decades. We identified 59 eligible studies and included an array of variables, including O3 measurements, number of air-quality monitoring stations used, relative risks, odds ratios, hazard ratios, number of hospital admissions, visits, or mortality, and size of population dataset used. Results: Approximately 83% of data in this review presents significant correlations of ozone with asthma, COPD, and ARDS. Studies that report negative or not significant associations mention a lack of data or topographic differences as the main issue with these divergent results. Studies consistently report summer as a period of particular concern. Portuguese data in this field is lacking. Conclusions: This research field is growing in interest and there is evidence that ozone plays a non-negligible role in health deterioration. The few Portuguese studies in this field seem aligned with the literature reviewed but more research is needed. Suggested improvements are more and better data through denser air-quality networks to accurately depict personal exposure to ozone. Homogenization of the exposure assessment concerning averaging times of ozone to daily maximum 8 h averages whenever possible. Risk increments based on 10 ppb instead of interquartile ranges. Lastly, contrary to some studies in this review, the topographic effect on concentrations and health deterioration should not be underestimated and seasonality should always be checked.

The impact of personal and outdoor temperature exposure during cold and warm seasons on lung function and respiratory symptoms in COPD

Rationale

Chronic obstructive pulmonary disease (COPD) patients often report aggravated symptoms due to heat and cold, but few studies have formally evaluated this.

Methodology

We followed 30 Boston-based former smokers with COPD for four non-consecutive 30-day periods over 12 months. Personal and outdoor temperature exposure were measured using portable and Boston-area outdoor stationary monitors. Participants recorded daily morning lung function measurements as well as any worsening breathing (breathlessness, chest tightness, wheeze) and bronchitis symptoms (cough, sputum colour and amount) compared to baseline. Using linear and generalised linear mixed-effects models, we assessed associations between personal and outdoor temperature exposure (1-3-day moving averages) and lung function and symptoms, adjusting for humidity, smoking pack-years and demographics. We also stratified by warm and cold season.

Results

Participants were on average 71.1±8.4 years old, with 54.4±30.7 pack-years of smoking. Each 5°C increase in personal temperature exposure was associated with 1.85 (95% CI 0.99-3.48) higher odds of worsening breathing symptoms. In the warm season, each 5°C increase in personal and outdoor temperature exposure was associated with 3.20 (95% CI 1.05-9.72) and 2.22 (95% CI 1.41-3.48) higher odds of worsening breathing symptoms, respectively. Each 5°C decrease in outdoor temperature was associated with 1.25 (95% CI 1.04-1.51) higher odds of worsening bronchitis symptoms. There were no associations between temperature and lung function.

Conclusions

Our findings suggest that higher temperature, including outdoor exposure during the warm season and personal temperature exposure year-round, may worsen dyspnoea, while colder outdoor temperature may trigger cough and phlegm symptoms among COPD patients.

Ambient heat and risks of emergency department visits among adults in the United States: time stratified case crossover study

OBJECTIVE

To quantify the association between ambient heat and visits to the emergency department (ED) for any cause and for cause specific conditions in the conterminous United States among adults with health insurance.

DESIGN

Time stratified case crossover analyses with distributed lag non-linear models.

SETTING

US nationwide administrative healthcare claims database.

PARTICIPANTS

All commercial and Medicare Advantage beneficiaries (74.2 million) aged 18 years and older between May and September 2010 to 2019.

MAIN OUTCOME MEASURES

Daily rates of ED visits for any cause, heat related illness, renal disease, cardiovascular disease, respiratory disease, and mental disorders based on discharge diagnosis codes.

RESULTS

21 996 670 ED visits were recorded among adults with health insurance living in 2939 US counties. Days of extreme heat-defined as the 95th centile of the local warm season (May through September) temperature distribution (at 34.4°C v 14.9°C national average level)-were associated with a 7.8% (95% confidence interval 7.3% to 8.2%) excess relative risk of ED visits for any cause, 66.3% (60.2% to 72.7%) for heat related illness, 30.4% (23.4% to 37.8%) for renal disease, and 7.9% (5.2% to 10.7%) for mental disorders. Days of extreme heat were associated with an excess absolute risk of ED visits for heat related illness of 24.3 (95% confidence interval 22.9 to 25.7) per 100 000 people at risk per day. Heat was not associated with a higher risk of ED visits for cardiovascular or respiratory diseases. Associations were more pronounced among men and in counties in the north east of the US or with a continental climate.

CONCLUSIONS

Among both younger and older adults, days of extreme heat are associated with a higher risk of ED visits for any cause, heat related illness, renal disease, and mental disorders. These results suggest that the adverse health effects of extreme heat are not limited to older adults and carry important implications for the health of adults across the age spectrum.

Hourly temperature variability and mortality in 31 major Chinese cities: Effect modification by individual characteristics, season and temperature zone

BACKGROUND

In the context of ongoing climate change, temperature variability (TV) has been considered as an important trigger of death. However, evidence of association between mortality and hourly temperature variability (HTV) is scarce at the multi-city level, and the time window of health effects of HTV is lack of investigation. This study aims at quantifying the mortality risk and burden of HTV and exploring subpopulations susceptible to HTV from a large-scale multi-city perspective.

METHODS

Data on daily number of deaths and meteorology were collected for 31 Chinese major cities during 2007-2013. HTV was calculated as the standard deviation of hourly temperature within a few days. The optimal exposure period of HTV was chosen according to multiple scientific criteria. A quasi-Poisson regression combined with distributed lag nonlinear model was used to assess the city-specific HTV-mortality associations. Then, meta-analysis was further applied to pool city-specific effect estimates. Finally, we calculated the fraction of mortality attributable to HTV. Stratification analyses were conducted by individual characteristics (i.e. age, sex, and educational attainment), season, and region.

RESULTS

HTV calculated in a relatively long-time window like 18 d (HTV_0-17) could capture the impact of HTV adequately. Per 1 °C raise of HTV_0-17 associated with 1.38% (95%CI: 0.77, 1.99) increase of non-accidental mortality. During the study period, 5.47% (95%CI: 1.06, 9.64) of non-accidental mortality could be attributed to HTV. The females, the elderly, and individuals with low education level were more susceptible to HTV than their counterparts, respectively. Moreover, a stronger HTV-mortality association was observed in individuals who live in warmer season and temperature zone.

CONCLUSION

HTV is associated with a considerable mortality burden, which may be modified by season, geographic and individual-level factors. Our findings highlight the practical importance of establishing early warning systems and promoting health education to mitigate the impacts of temperature variability.

Using social security number to identify sub-populations vulnerable to the health impacts from extreme heat in Florida, U.S

BACKGROUND

Some socioeconomically vulnerable groups may experience disproportionately higher risk of extreme heat illness than other groups, but no study has utilized the presence/absence of a social security number (SSN) as a proxy for vulnerable sub-populations.

METHODS

This study focused on the warm season from 2008 to 2012 in Florida, U.S. With a total number of 8,256,171 individual level health outcomes, we devised separate case-crossover models for five heat-sensitive health outcomes (cardiovascular disease, dehydration, heat-related illness, renal disease, and respiratory disease), type of health care visit (emergency department (ED) and hospitalization), and patients reporting/not reporting an SSN. Each stratified model also considered potential effect modification by sex, age, or race/ethnicity.

RESULTS

Mean temperature raised the odds of five heat-sensitive health outcomes with the highest odds ratios (ORs) for heat-related illness. Sex significantly modified heat exposure effects for dehydration ED visits (Males: 1.145, 95 % CI: 1.137-1.153; Females: 1.110, 95 % CI: 1.103-1.117) and hospitalization (Males: 1.116, 95 % CI: 1.110-1.121; Females: 1.100, 95 % CI: 1.095-1.105). Patients not reporting an SSN between 25 and 44 years (1.264, 95 % CI: 1.192-1.340) exhibited significantly higher dehydration ED ORs than those reporting an SSN (1.146, 95 % CI: 1.136-1.157). We also observed significantly higher ORs for cardiovascular disease hospitalization from the no SSN group (SSN: 1.089, 95 % CI: 1.088-1.090; no SSN: 1.100, 95 % CI: 1.091-1.110).

CONCLUSIONS

This paper partially supports the idea that individuals without an SSN could experience higher risks of dehydration (for those 25-45 years), renal disease, and cardiovascular disease than those with an SSN.