Case-crossover analysis of short-term particulate matter exposures and stroke in the health professionals follow-up study

Association between short-term ozone exposure and allergic conjunctivitis in China: A multi-city case-crossover study

Short-term exposure to ozone has been linked to multiple allergic diseases, but the relationship between ozone exposure and allergic conjunctivitis (AC) remains unclear. This study aimed to investigate the association between short-term exposure to ozone and the risk of AC. We conducted a time-stratified case-crossover study across five Chinese cities from 2014 to 2022. Daily outpatient visit records for AC were identified in five hospitals using either the diagnosis name or ICD-10 code H10.1. Data on air pollution and meteorological conditions were also collected. We first examined the city-specific association between short-term ozone exposure and AC using conditional logistic regression. A random-effects meta-analysis was then conducted to obtain overall estimates. During the study period, 130,093 outpatient visits for AC occurred, with 58.8% (76,482) being male and 41.2% (53,611) female. A one-standard-deviation (SD) increase in ozone was associated with an 8.3% increase (95% CI: 3.8%, 13.0%) in AC outpatient visits. Similar positive associations were observed when adjusting for other pollutants (PM2.5, CO, SO2 and NO2) in two-pollutant and multi-pollutant models. Furthermore, the positive association remained consistent when using mixed-effects regression models or further adjusting for meteorological conditions. In addition, no effect modification of the AC-ozone association by sex, age and season was apparent. This study provides evidence supporting a positive association between short-term ozone exposure and AC risk in China. This highlights the potential value of mitigating ozone pollution to reduce the risk of ocular surface disorders.

Short-term exposure to PM2.5 constituents, extreme temperature events and stroke mortality

BACKGROUND

Fine particulate matter (PM2.5) pollution and extreme temperature events (ETEs) are main environmental threats to human health. Elevated stroke mortality has been growingly linked to PM2.5 mass exposure, while its relationship with PM2.5 constituents was extensively unstudied across the globe. Additionally, no prior assessments have investigated the interactive effects of PM2.5 constituents and ETEs on stroke mortality.

METHODS

Province-wide records of 320,372 stroke deaths collected in eastern China during 2016-2019 were analyzed using an individual-level time-stratified case-crossover design. Daily gridded estimates of PM2.5 mass and its major constituents (i.e., black carbon [BC], organic matter [OM], ammonium [NH4+], sulfate [SO42-], and nitrate [NO3-]) were assigned to stroke cases on case days and control days at the residential address. We assessed 12 ETEs defined by multiple combinations of air temperature thresholds (2.5-10th percentiles for cold spell, 90-97.5th percentiles for heat wave) and durations (2-4 days). Conditional logistic regression model was applied to investigate associations of short-term exposure to PM2.5 constituents and ETEs with stroke mortality. Odds ratio and its 95% confidence interval (CI) were assessed for an interquartile range (IQR) increase in each PM2.5 constituent and on ETEs days compared with non-ETEs days. Additive interactive effects were quantitatively evaluated via relative excess odds due to interaction (REOI), attributable proportion due to interaction (AP), and synergy index (SI).

RESULTS

Elevated overall stroke mortality was significantly related to PM2.5 constituents, with the largest odds observed for NO3- (1.04, 95% CI: 1.03-1.04, IQR = 11.25 μg/m3), followed by OM (1.03, 1.03-1.04, IQR = 7.97 μg/m3), NH4+ (1.03, 1.02-1.04, IQR = 6.66 μg/m3), BC (1.03, 1.02-1.03, IQR = 1.41 μg/m3), and SO42- (1.03, 1.02-1.03, IQR = 6.67 μg/m3). Overall, higher risks of stroke mortality were identified in analyses using more rigorous thresholds and lengthened durations of ETEs definitions, ranging from 1.19 (1.17-1.21) to 1.55 (1.51-1.60) for heat wave, and 1.03 (1.02-1.05) to 1.11 (1.08-1.15) for cold spell, respectively. We observed consistent evidence for the synergistic effects of heat wave and PM2.5 constituents on both ischemic and hemorrhagic stroke mortality, where compound exposures to heat wave and secondary inorganic aerosols (i.e., NO3-, SO42-, and NH4+) posed greater increases in risk (0.23< REOI <0.81, 0.16< AP <0.39, and 2.63< SI <8.19).

CONCLUSIONS

Short-term exposure to both PM2.5 constituents and ETEs were associated with heightened stroke mortality, and heat wave may interact synergistically with PM2.5 constituents to trigger stroke deaths.

Interaction between ambient CO and temperature or relative humidity on the risk of stroke hospitalization

Although the independent effects of ambient CO, temperature or humidity on stroke have been confirmed, it is still unclear where there is an interaction between these factors and who is sensitive populations for these. The stroke hospitalization and ambient CO, temperature, humidity data were collected in 22 Counties and districts of Ningxia, China in 2014-2019. The lagged effect of ambient CO, temperature or humidity were analyze by the generalized additive model; the interaction were evaluated by the bivariate response surface model and stratified analysis with relative excessive risk (RERI). High temperature and CO levels had synergistic effects on hemorrhagic stroke (RERI = 0.05, 95% CI 0.033-0.086) and ischemic stroke (RERI = 0.035, 95% CI 0.006-0.08). Low relative humidity and CO were synergistic in hemorrhagic stroke (RERI = 0.192, 95% CI 0.184-0.205) and only in ischemic stroke in the elderly group (RERI = 0.056, 95% CI 0.025-0.085). High relative humidity and CO exhibited antagonistic effects on the risk of ischemic stroke hospitalization in both male and female groups (RERI = - 0.088, 95% CI - 0.151to - 0.031; RERI = - 0.144, 95% CI - 0.216 to - 0.197). Exposure to CO increases the risk of hospitalization related to hemorrhagic and ischemic strokes. CO and temperature or humidity interact with risk of stroke hospitalization with sex and age differences.

Air Pollution Increases Risk of Occurrence of Intracerebral Haemorrhage but Not of Subarachnoid Haemorrhage: Time-Series Cross-Sectional Study

(1) Background: Haemorrhagic strokes (HS), including intracerebral (ICH) and subarachnoid haemorrhages (SAH), account for approximately 10-15% of strokes worldwide but are associated with worse functional outcomes and higher rates of mortality, and financial burden than ischemic stroke. There is evidence that confirmed poor air quality may increase the incidence of haemorrhagic strokes. The aim of our study was to evaluate the association between individual ambient air pollutants and the risk of haemorrhagic stroke in an urban environment without high levels of air pollution. (2) Methods: A time-series cross-sectional study design was used. A daily air pollution concentration (Agency of Regional Air Quality Monitoring in the Gdansk Metropolitan Area) and incidence of haemorrhagic strokes (National Health Fund) were obtained and covered the time period from 1 January 2014 to 31 December 2018. A generalised additive model with Poisson regression was used to estimate the associations between 24-h mean concentrations of SO2, NO, NO2, NOx, CO, PM10, PM2.5, and O3 and a daily number of haemorrhagic strokes. (3) Results: The single-day lag model results showed that NO2, NO and NOx exposure was associated with increased risk of ICH (88% events) with RR of 1.059 (95% CI: 1.015-1.105 for lag0), 1.033 (95% CI: 1.007-1.060 for lag0) and 1.031 (95% CI: 1.005-1.056 for lag0), but not for SAH (12% events). Exposure to CO was related to a substantial and statistically significant increase in incidence for 1.031 (95% CI: 1.002-1.061 for lag0) but not for SAH. Higher SO2, PM10, PM2.5, and O3 exposures were not significantly related to both ISC and SAH. (4) Conclusions: In this time-series cross-sectional study, we found strong evidence that supports the hypothesis that transient elevations in ambient NO2, NO and CO are associated with a higher relative risk of intracerebral but not subarachnoid haemorrhage.

Differentiating the impact of fine and coarse particulate matter on cause-specific cerebrovascular mortality: An individual-level, case-crossover study

BACKGROUND AND OBJECTIVES

Many studies suggested that short-term exposure to fine particulate matter (PM2.5) and coarse particulate matter (PM2.5-10) was linked to elevated risk of cerebrovascular disease. However, little is known about the potentially differential effects of PM2.5 and PM2.5-10 on various types of cerebrovascular disease.

METHODS

We collected individual cerebrovascular death records for all residents in Shanghai, China from 2005 to 2021. Residential daily air pollution data were predicted from a satellite model. The associations between particulate matters (PM) and cerebrovascular mortality were investigated by an individual-level, time-stratified, case-crossover design. The data was analyzed by the conditional logistic regression combined with the distributed lag model with a maximum lag of 7 days. Furthermore, we explored the effect modifications by sex, age and season.

RESULTS

A total of 388,823 cerebrovascular deaths were included. Monotonous increases were observed for mortality of all cerebrovascular diseases except for hemorrhagic stroke. A 10 μg/m3 rise in PM2.5 was related to rises of 1.35% [95% confidence interval (CI): 1.04%, 1.66%] in mortality of all cerebrovascular diseases, 1.84% (95% CI: 1.25%, 2.44%) in ischemic stroke, 1.53% (95% CI: 1.07%, 1.99%) in cerebrovascular sequelae and 1.56% (95% CI: 1.08%, 2.05%) in ischemic stroke sequelae. The excess risk estimates per each 10 μg/m3 rise in PM2.5-10 were 1.47% (95% CI: 1.10%, 1.84%), 1.53% (95% CI: 0.83%, 2.24%), 1.93% (95% CI: 1.38%, 2.49%) and 2.22% (95% CI: 1.64%, 2.81%), respectively. The associations of both pollutants with all cerebrovascular outcomes were robust after controlling for co-pollutants. The associations were greater in females, individuals > 80 years, and during the warm season.

CONCLUSIONS

Short-term exposures to both PM2.5 and PM2.5-10 may independently increase the mortality risk of cerebrovascular diseases, particularly of ischemic stroke and stroke sequelae.

Short-Term Nitrogen Dioxide Exposure and Emergency Hospital Admissions for Asthma in Children: A Case-Crossover Analysis in England

Background

There is an increasing body of evidence associating short-term ambient nitrogen dioxide (NO2) exposure with asthma-related hospital admissions in children. However, most studies have relied on temporally resolved exposure information, potentially ignoring the spatial variability of NO2. We aimed to investigate how daily NO2 estimates from a highly resolved spatio-temporal model are associated with the risk of emergency hospital admission for asthma in children in England.

Methods

We conducted a time-stratified case-crossover study including 111,766 emergency hospital admissions for asthma in children (aged 0-14 years) between 1st January 2011 and 31st December 2015 in England. Daily NO2 levels were predicted at the patients' place of residence using spatio-temporal models by combining land use data and chemical transport model estimates. Conditional logistic regression models were used to obtain the odds ratios (OR) and confidence intervals (CI) after adjusting for temperature, relative humidity, bank holidays, and influenza rates. The effect modifications by age, sex, season, area-level income deprivation, and region were explored in stratified analyses.

Results

For each 10 µg/m³ increase in NO2 exposure, we observed an 8% increase in asthma-related emergency admissions using a five-day moving NO2 average (mean lag 0-4) (OR 1.08, 95% CI 1.06-1.10). In the stratified analysis, we found larger effect sizes for male (OR 1.10, 95% CI 1.07-1.12) and during the cold season (OR 1.10, 95% CI 1.08-1.12). The effect estimates varied slightly by age group, area-level income deprivation, and region.

Significance

Short-term exposure to NO2 was significantly associated with an increased risk of asthma emergency admissions among children in England. Future guidance and policies need to consider reflecting certain proven modifications, such as using season-specific countermeasures for air pollution control, to protect the at-risk population.

Comparison of PM2.5 Air Pollution Exposures and Health Effects Associations Using 11 Different Modeling Approaches in the Women's Health Initiative Memory Study (WHIMS)

BACKGROUND

Many approaches to quantifying air pollution exposures have been developed. However, the impact of choice of approach on air pollution estimates and health-effects associations remains unclear.

OBJECTIVES

Our objective is to compare particulate matter with aerodynamic diameter ≤ 2.5 μ m (PM 2.5 ) concentrations and resulting health effects associations using multiple estimation approaches previously used in epidemiologic analyses.

METHODS

We assigned annual PM 2.5 exposure estimates from 1999 to 2004 derived from 11 different approaches to Women's Health Initiative Memory Study (WHIMS) participant addresses within the contiguous US. Approaches included geostatistical interpolation approaches, land-use regression or spatiotemporal models, satellite-derived approaches, air dispersion and chemical transport models, and hybrid models. We used descriptive statistics and plots to assess relative and absolute agreement among exposure estimates and examined the impact of approach on associations between PM 2.5 and death due to natural causes, cardiovascular disease (CVD) mortality, and incident CVD events, adjusting for individual-level covariates and climate-based region.

RESULTS

With a few exceptions, relative agreement of approach-specific PM 2.5 exposure estimates was high for PM 2.5 concentrations across the contiguous US. Agreement among approach-specific exposure estimates was stronger near PM 2.5 monitors, in certain regions of the country, and in 2004 vs. 1999. Collectively, our results suggest but do not quantify lower agreement at local spatial scales for PM 2.5 . There was no evidence of large differences in health effects associations with PM 2.5 among estimation approaches in analyses adjusted for climate region.

CONCLUSIONS

Different estimation approaches produced similar spatial patterns of PM 2.5 concentrations across the contiguous US and in areas with dense monitoring data, and PM 2.5 -health effects associations were similar among estimation approaches. PM 2.5 estimates and PM 2.5 -health effects associations may differ more in samples drawn from smaller areas or areas without substantial monitoring data, or in analyses with finer adjustment for participant location. Our results can inform decisions about PM 2.5 estimation approach in epidemiologic studies, as investigators balance concerns about bias, efficiency, and resource allocation. Future work is needed to understand whether these conclusions also apply in the context of other air pollutants of interest. https://doi.org/10.1289/EHP12995.

Effect of Air Pollution Particulate Matter on Ischemic and Hemorrhagic Stroke: A Scoping Review

Air pollution particulate matter (PM) exposure has been established as a risk factor for stroke. However, few studies have investigated the effects of PM exposure on stroke subtypes (ischemic and hemorrhagic stroke). Ischemic (IS) and hemorrhagic strokes (HS) involve distinctive pathophysiological pathways and may be differentially influenced by PM exposure. This review aims to characterize the effects of PM exposure on ischemic and hemorrhagic strokes. It also identifies subpopulations that may be uniquely vulnerable to PM toxicity. Pubmed was queried from 2000 to 2023 to identify clinical and epidemiological studies examining the association between PM exposure and stroke subtypes (ischemic and hemorrhagic stroke). Inclusion criteria were: 1) articles written in English 2) clinical and epidemiological studies 3) studies with a clear definition of stroke, IS, HS, and air pollution 4) studies reporting the effects of PM and 5) studies that included distinct analyses per stroke subtype. Two independent reviewers screened the literature for applicable studies. A total of 50 articles were included in this review. Overall, PM exposure increases ischemic stroke risk in both lightly and heavily polluted countries. The association between PM exposure and hemorrhagic stroke is variable and may be influenced by a country's ambient air pollution levels. A stronger association between PM exposure and stroke is demonstrated in older individuals and those with pre-existing diabetes. There is no clear effect of sex or hypertension on PM-associated stroke risk. Current literature suggests PM exposure increases ischemic stroke risk, with an unclear effect on hemorrhagic stroke risk. Older patients and those with pre-existing diabetes may be the most vulnerable to PM toxicity. Future investigations are needed to characterize the influence of sex and hypertension on PM-associated stroke risk.

Effect of neighbourhood greenness on the association between air pollution and risk of stroke first onset: A case-crossover study in shandong province, China

BACKGROUND

Higher neighbourhood greenness is associated with beneficial health outcomes, and short-term exposure to air pollution is associated with an elevated risk of stroke onset. However, little is known about their interactions.

METHODS

Daily data on stroke first onset were collected from 20 counties in Shangdong Province, China, from 2013 to 2019. The enhanced vegetation index (EVI) and concentrations of fine particulate matter (PM2.5), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and sulfur dioxide (SO2) were calculated for each individual at the village or community level based on their home address to measure their neighbourhood exposure to greenness and air pollution. EVI was categorised as low or high, and a time-stratified case-crossover design was used to estimate the percent excess risk (ER%) of stroke associated with short-term exposure to air pollution. We further stratified greenness on the basis of EVI values into quartiles and introduced interaction terms between air pollutant concentrations and the median EVI values of the quartiles to assess the effect of greenness on the associations between short-term exposure and stroke.

RESULTS

Individuals living in the high-greenness areas had weaker associations between total stroke risk and exposure to NO2 (low greenness: ER% = 1.765% [95% CI 1.205%-2.328%]; high greenness: ER% = 0.368% [95% CI -0.252% to 0.991%]; P = 0.001), O3 (low greenness: 0.476% [95% CI 0.246%-0.706%]; high greenness: ER% = 0.085% [95% CI -0.156% to 0.327%]; P = 0.011), and SO2 (low greenness: 0.632% [95% CI 0.138%-1.129%]; high greenness: ER% = -0.177% [95% CI -0.782% to 0.431%]; P = 0.035).

CONCLUSION

Residence in areas with higher greenness was related to weaker associations between air pollution and stroke risk, suggesting that effectively planning green spaces can improve public health.

Cleaner outdoor air diminishes the overall risk of intracerebral hemorrhage but brings differential benefits to subpopulations: a time-stratified case-crossover study

BACKGROUND

Short-term air pollution exposure and intracerebral hemorrhage (ICH) risk are related. However, the impact of the pollutant levels decline on this relationship, which attributes to clean air policy implementation and the COVID-19 pandemic lockdown, is unclear. In the present research, we explored the influence of different pollutant levels on ICH risk during eight years in a southwestern China megacity.

METHODS

Our research used a time-stratified case-crossover design. We retrospectively analyzed ICH patients in a teaching hospital from January 1, 2014, to December 31, 2021, and divided 1571 eligible cases into two groups (1st group: 2014-2017; 2nd group: 2018-2021). We observed the trend of every pollutant in the entire study period and compared the pollution levels in each group, using air pollutants data (PM2.5, PM10, SO2, NO2, CO, and O3) documented by the local government. We further established a single pollutant model via conditional logistic regression to analyze the association between short-term air pollutants exposure and ICH risk. We also discussed the association of pollution levels and ICH risk in subpopulations according to individual factors and monthly mean temperature.

RESULTS

We found that five air pollutants (PM2.5, PM10, SO2, NO2, CO) exhibited a continuous downward trend for the whole duration, and the daily concentration of all six pollutants decreased significantly in 2018-2021 compared with 2014-2017. Overall, the elevation of daily PM2.5, SO2, and CO was associated with increased ICH risk in the first group and was not positively associated with risk escalation in the second group. For patients in subgroups, the changes in the influence of lower pollutant levels on ICH risk were diverse. In the second group, for instance, PM2.5 and PM10 were associated with lower ICH risk in non-hypertension, smoking, and alcohol-drinking participants; however, SO2 had associations with increased ICH risk for smokers, and O3 had associations with raised risk in men, non-drinking, warm month population.

CONCLUSIONS

Our study suggests that decreased pollution levels diminish the adverse effects of short-term air pollutants exposure and ICH risk in general. Nevertheless, the influence of lower air pollutants on ICH risk in subgroups is heterogeneous, indicating unequal benefits among subpopulations.

Short-term effects of individual exposure to PM2.5 on hospital admissions for myocardial infarction and stroke: a population-based case-crossover study in Guangzhou, China

Some studies have investigated the effects of PM_2.5 on cardiovascular diseases based on the population-average exposure data from several monitoring stations. No one has explored the short-term effect of PM_2.5 on cardiovascular hospitalizations using individual-level exposure data. We assessed the short-term effects of individual exposure to PM_2.5 on hospitalizations for myocardial infarction (MI) and stroke in Guangzhou, China, during 2014-2019. The population-based data on cardio-cerebrovascular events were provided by Guangzhou Center for Disease Control and Prevention. Average annual percent changes (AAPCs) were used to describe trends in the hospitalization rates of MI and stroke. The conditional logistic regression model with a time-stratified case-crossover design was applied to estimate the effects of satellite-retrieved PM_2.5 with 1-km resolution as individual-level exposure. Furthermore, we performed stratified analyses by demographic characteristics and season. There were 28,346 cases of MI, 188,611, and 36,850 cases of ischemic stroke (IS) and hemorrhagic stroke (HS), respectively, with an annual average hospitalization rate of 37.2, 247, and 48.4 per 100,000 people. Over the six-year study period, significant increasing trends in the hospitalization rates were observed with AAPCs of 12.3% (95% confidence interval [CI]: 7.24%, 17.6%), 13.1% (95% CI: 9.54%, 16.7%), and 9.57% (95% CI: 6.27%, 13.0%) for MI, IS, and HS, respectively. A 10 μg/m³ increase in PM_2.5 was associated with an increase of 1.15% (95% CI: 0.308%, 1.99%) in MI hospitalization and 1.29% (95% CI: 0.882%, 1.70%) in IS hospitalization. A PM_2.5-associated reduction of 1.17% (95% CI: 0.298%, 2.03%) was found for HS hospitalization. The impact of PM_2.5 was greater in males than in females for MI hospitalization, and greater effects were observed in the elderly (≥ 65 years) and in cold seasons for IS hospitalization. Our study added important evidence on the adverse effect of PM_2.5 based on satellite-retrieved individual-level exposure data.

The new WHO air quality guidelines for PM2.5: predicament for small/medium cities

The global burden of disease estimated that approximately 7.1 million deaths worldwide were related to air pollution in 2016. However, only a limited number of small- and middle-sized cities have air quality monitoring networks. To date, air quality in terms of particulate matter is still mainly focused on mass concentration, with limited compositional monitoring even in mega cities, despite evidence indicating differential toxicity of particulate matter. As this evidence is far from conclusive, we conducted PM_2.5 bioaccessibility studies of potentially harmful elements in a medium-sized city, Londrina, Brazil. The data was interpreted in terms of source apportionment, the health risk evaluation and the bioaccessibility of inorganic contents in an artificial lysosomal fluid. The daily average concentration of PM_2.5 was below the WHO guideline, however, the chemical health assessment indicated a considerable health risk. The in vitro evaluation showed different potential mobility when compared to previous studies in large-sized cities, those with 1 million inhabitants or more (Curitiba and Manaus). The new WHO guideline for PM_2.5 mass concentration puts additional pressure on cities where air pollution monitoring is limited and/or neglected, because decision making is mainly revenue-driven and not socioeconomic-driven. Given the further emerging evidence that PM chemical composition is as, or even more, important than mass concentration levels, the research reported in the paper could pave the way for the necessary inter- and intra-city collaborations that are needed to address this global health challenge.

Air pollution and stroke hospitalization in the Beibu Gulf Region of China: A case-crossover analysis

BACKGROUND

The relationship between air pollution and stroke has been extensively studied, however, the evidence regarding the association between air pollution and hospitalization due to stroke and its subtypes in coastal areas of China is limited.

OBJECTIVE

To estimate the associations between air pollution and hospitalizations of stroke and its subtypes in the Beibu Gulf Region of China.

METHODS

We conducted a time-stratified case-crossover study in 15 cities in Beibu Gulf Region in China from 2013 to 2016. Exposures to PM₁, PM_2.5, PM₁₀, SO₂, NO₂, O₃, and CO on the case and control days were assessed at residential addresses using bilinear interpolation. Conditional logistic regressions were constructed to estimate city-specific associations adjusting for meteorological factors and public holidays. Meta-analysis was further conducted to pool all city-level estimates.

RESULTS

There were 271,394 case days and 922,305 control days. The odds ratios (ORs) for stroke hospitalizations associated with each interquartile range (IQR) increase in 2-day averages of SO₂ (IQR: 10.8 µg/m³), NO₂ (IQR: 11.2 µg/m³), and PM₁₀ (IQR: 37 µg/m³) were 1.047 (95 % CI [confidence interval]: 1.015-1.080), 1.040 (95 % CI: 1.027-1.053), and 1.018 (95 % CI: 1.004-1.033), respectively. The associations with hospitalizations of ischemic stroke were significant for all seven pollutants, while the association with hemorrhagic stroke was significant only for CO. The associations of SO₂, NO₂, and O₃ with stroke hospitalization were significantly stronger in the cool season.

CONCLUSIONS

Short-term increase in SO₂, NO₂, and PM₁₀ might be important triggers of stroke hospitalization. All seven air pollutants were associated with ischemic stroke hospitalization, while only CO was associated with hemorrhagic stroke hospitalization. These results should be considered in public health policy.

Assessment of Low-Level Air Pollution and Cardiovascular Incidence in Gdansk, Poland: Time-Series Cross-Sectional Analysis

(1) Background: More than 1.8 million people in the European Union die every year as a result of CVD, accounting for 36% of all deaths with a large proportion being premature (before the age of 65). There are more than 300 different risk factors of CVD, known and air pollution is one of them. The aim of this study was to investigate whether daily cardiovascular mortality was associated with air pollutants and meteorological conditions in an urban environment with a low level of air pollution. (2) Methods: Data on daily incidence of strokes and myocardial infarctions in the city of Gdansk were obtained from the National Health Fund (NHF) and covered the period from 1 January 2014 to 31 December 2018. Data on the level of pollution, i.e., SO2, NO, NO2, NOx, CO, PM10, PM2.5, CO2, O3 and meteorological conditions came from the foundation: Agency of Regional Air Quality Monitoring in the Gdańsk metropolitan area (ARMAG). Using these data, we calculated mean values with standard deviation (SD) and derived the minimum and maximum values and interquartile range (IQR). Time series regression with Poisson distribution was used in statistical analysis. (4) Results: Stroke incidence is significantly affected by an increase in concentrations of NO, NO2 and NOx with RRs equal to 1.019 (95%CI: 1.001–1.036), 1.036 (95%CI: 1.008–1.064) and 1.017 (95%CI: 1.000–1.034) for every increase in IQR by 14.12, 14.62 and 22.62 μg/m3, respectively. Similarly, myocardial infarction incidence is significantly affected by an increase in concentrations of NO, NO2 and NOx with RRs equal to 1.030 (95%CI: 1.011–1.048), 1.053 (95%CI: 1.024–1.082) and 1.027 (95%CI: 1.010–1.045) for every increase in IQR by 14.12, 14.62 and 22.62 μg/m3, respectively. Both PM10 and PM2.5 were positively associated with myocardial infarction incidence. (5) Conclusions: In this time-series cross-sectional study, we found strong evidence that support the hypothesis that transient elevations in ambient PM2.5, PM10, NO2, SO2 and CO are associated with higher relative risk of ischemic stroke and myocardial infarction incidents.

Ambient Air Pollution and Stroke: An Updated Review

Despite recent advances in treatment and prevention, stroke remains a leading cause of morbidity and mortality. There is a critical need to identify novel modifiable risk factors for disease, including environmental agents. A body of evidence has accumulated suggesting that elevated levels of ambient air pollutants may not only trigger cerebrovascular events in susceptible people (short-term exposures) but also increase the risk of future events (long-term average exposures). This review assesses the updated evidence for both short and long-term exposure to ambient air pollution as a risk factor for stroke incidence and outcomes. It discusses the potential pathophysiologic mechanisms and makes recommendations to mitigate exposure on a personal and community level. The evidence indicates that reduction in air pollutant concentrations represent a significant population-level opportunity to reduce risk of cerebrovascular disease.

Short-term effect of PM2.5 on stroke in susceptible populations: A case-crossover study

BACKGROUND

Fine particulate matter (PM2.5) is a risk factor for stroke, and patients with pre-existing diseases appear to be particularly susceptible. We conducted a case-crossover study to examine the association between short-term exposure to fine particulate matter (PM2.5) and hospital admission for stroke in individuals with atrial fibrillation (AF), hypertension, diabetes, or hyperlipidemia.

METHODS

Patients diagnosed with acute ischemic stroke (AIS) were recruited from 2015 to 2017 in Chinese Stroke Center Alliances. We estimated daily PM2.5 average exposures with a spatial resolution of 0.1° using a data assimilation approach combining satellite measurements, air model simulations, and monitoring values. Conditional logistic regression was used to assess PM2.5-related stroke risk in patients with pre-existing medical co-morbidities.

RESULTS

A total of 155,616 patients diagnosed with AIS were admitted. Patients with a history of AF (n = 15,430), hypertension (n = 138,220), diabetes (n = 43,737), or hyperlipidemia (n = 16,855) were assessed separately. A 10 µg/m³ increase in daily PM2.5 was associated with a significant increase in AIS for individuals with AF at lag 4 (odds ratio (OR), 1.008; 95% confidence interval (CI), 1.002-1.014), and with hypertension (OR, 1.008; 95% CI, 1.006-1.010), diabetes (OR, 1.006; 95% CI, 1.003-1.010), and hyperlipidemia (OR, 1.007; 95% CI, 1.001-1.012) at lags 0-7. Elderly (⩾ 65 years old) and female patients with AF had significantly higher associations at lag 5 (OR, 1.009; 95% CI, 1.002-1.015) and lag 5 (OR, 1.010; 95% CI, 1.002-1.018), respectively.

CONCLUSION

Short-term exposure to PM2.5 is significantly associated with hospital admission for stroke in individuals with pre-existing medical histories, especially in older or female patients with AF. Preventive measures to reduce PM2.5 concentrations are particularly important in individuals with other medical co-morbidities.

Association between air temperature and emergency admission for esophagogastric variceal bleeding: a case-crossover study in Beijing, China

BACKGROUND AND AIMS

Studies concerning the impact of air temperature on esophagogastric variceal bleeding (EGVB) have yielded conflicting results. Our study aimed to evaluate the correlation between air temperature and EGVB.

METHODS

A time-stratified case-crossover study design was performed. Patients received emergency gastroscopic hemostasis for upper gastrointestinal bleeding between Jan 1, 2014, and Dec 31, 2018 in the Fifth Medical Center of PLA General Hospital were enrolled. Conditional logistic regression analysis was applied to determine the association between air temperature and EGVB for different lag structures.

RESULTS

A total of 4204 cirrhotic patients diagnosed with EGVB and received emergency gastroscopic hemostasis were enrolled. The mean number of daily EGVB cases peaked in October (2.65 ± 1.69) and fell to the lowest level in July (1.86 ± 1.38), and was 2.38 ± 1.58 in spring, 2.00 ± 1.46 in summer, 2.37 ± 1.58 in autumn, and 2.45 ± 1.58 in winter, respectively (P < 0.0001). In conditional logistic regression analysis, no significant correlations between air temperature and EGVB were observed and no significant difference were found when stratified by age, sex, etiology, liver cancer status, and grade of varices.

CONCLUSION

Emergency admission for EGVB showed significant monthly and seasonal fluctuations, while in conditional logistic regression analysis, no association between minimum temperature and emergency admission for EGVB were observed.

Climate change and the prevention of cardiovascular disease

Climate change is a worsening global crisis that will continue negatively impacting population health and well-being unless adaptation and mitigation interventions are rapidly implemented. Climate change-related cardiovascular disease is mediated by air pollution, increased ambient temperatures, vector-borne disease and mental health disorders. Climate change-related cardiovascular disease can be modulated by climate change adaptation; however, this process could result in significant health inequity because persons and populations of lower socioeconomic status have fewer adaptation options. Clear scientific evidence for climate change and its impact on human health have not yet resulted in the national and international impetus and policies necessary to slow climate change. As respected members of society who regularly communicate scientific evidence to patients, clinicians are well-positioned to advocate on the importance of addressing climate change. This narrative review summarizes the links between climate change and cardiovascular health, proposes actionable items clinicians and other healthcare providers can execute both in their personal life and as an advocate of climate policies, and encourages communication of the health impacts of climate change when counseling patients. Our aim is to inspire the reader to invest more time in communicating the most crucial public health issue of the 21st century to their patients.

Acute effect of air pollutants' peak-hour concentrations on ischemic stroke hospital admissions among hypertension patients in Beijing, China, from 2014 to 2018

Air pollutants' effect on ischemic stroke (IS) has been widely reported. But the effect of high-level concentrations during people's outdoor periods among hypertension patients was unknown. Peak-hour concentrations were defined considering air pollutants' high concentrations as well as people's outdoor periods. We conducted a time-series study and used the generalized additive model to analyze peak-hour concentrations' acute effect. A total of 315,499 IS patients comorbid with hypertension were admitted to secondary and above hospitals in Beijing from 2014 to 2018. A 10 µg/m³ (CO: 1 mg/m³) increase of the peak-hour concentrations was positively associated with IS hospital admissions among hypertension patients. The maximum effect sizes were as follows: for PM_2.5, 0.17% (95% confidence interval [CI]: 0.10-0.24%) at Lag0 and 0.22% (95% CI: 0.12-0.33%) at Lag0-5; for PM₁₀, 0.09% (95% CI: 0.05-0.13%) at Lag5 and 0.17% (95% CI: 0.09-0.26%) at Lag0-5; for SO₂, 0.87% (95% CI: 0.46-1.29%) at Lag5; for NO₂, 0.83% (95% CI: 0.62-1.04%) at Lag0 and 0.86% (95% CI: 0.59-1.13%) at Lag0-1; for CO 1.23% (95% CI: 0.66-1.80%) at Lag0 and 1.33% (95% CI: 0.33-2.35%) at Lag0-5; for O₃ 0.23% (95% CI: 0.12-0.35%) at Lag0 and 0.20% (95% CI: 0.05-0.34%) at Lag0-1. The effect sizes of PM_2.5, NO₂, and O₃ remained significant after adjusting daily mean. Larger effect sizes were observed for PM_2.5 and PM₁₀ in cool season and for O₃ in warm season. As significant exposure indicators of air pollution, peak-hour concentrations exposure increased the risk of IS hospital admissions among hypertension patients and it is worthy of consideration in relative environmental standard. It is suggested for hypertension patients to avoid outdoor activity during peak hours. More relevant searches are required to further illustrate air pollutant's effect on chronic disease population.

Combined effects of air pollution and extreme heat events among ESKD patients within the Northeastern United States

BACKGROUND

Increasing number of studies have linked air pollution exposure with renal function decline and disease. However, there is a lack of data on its impact among end-stage kidney disease (ESKD) patients and its potential modifying effect from extreme heat events (EHE).

METHODS

Fresenius Kidney Care records from 28 selected northeastern US counties were used to pool daily all-cause mortality (ACM) and all-cause hospital admissions (ACHA) counts. County-level daily ambient PM_2.5 and ozone (O₃) were estimated using a high-resolution spatiotemporal coupled climate-air quality model and matched to ESKD patients based on ZIP codes of treatment sites. We used time-stratified case-crossover analyses to characterize acute exposures using individual and cumulative lag exposures for up to 3 days (Lag 0-3) by using a distributed lag nonlinear model framework. We used a nested model comparison hypothesis test to evaluate for interaction effects between air pollutants and EHE and stratification analyses to estimate effect measures modified by EHE days.

RESULTS

From 2001 to 2016, the sample population consisted of 43,338 ESKD patients. We recorded 5217 deaths and 78,433 hospital admissions. A 10-unit increase in PM_2.5 concentration was associated with a 5% increase in ACM (rate ratio [RR_Lag0-3]: 1.05, 95% CI: 1.00-1.10) and same-day O₃ (RR_Lag0: 1.02, 95% CI: 1.01-1.03) after adjusting for extreme heat exposures. Mortality models suggest evidence of interaction and effect measure modification, though not always simultaneously. ACM risk increased up to 8% when daily ozone concentrations exceeded National Ambient Air Quality Standards established by the United States, but the increases in risk were considerably higher during EHE days across lag periods.

CONCLUSION

Our findings suggest interdependent effects of EHE and air pollution among ESKD patients for all-cause mortality risks. National level assessments are needed to consider the ESKD population as a sensitive population and inform treatment protocols during extreme heat and degraded pollution episodes.

Analysis of long- and medium-term particulate matter exposures and stroke in the US-based Health Professionals Follow-up Study

PURPOSE

Stroke is a leading cause of mortality worldwide, and air pollution is the third largest contributor to global stroke burden. Existing studies investigating the association between long-term exposure to particulate matter (PM) and stroke incidence have been mixed and very little is known about the associations with medium-term exposures. Therefore, we wanted to evaluate these associations in an cohort of male health professionals.

METHODS

We assessed the association of PM exposures in the previous 1 and 12 months with incident total, ischemic, and hemorrhagic stroke in 49,603 men in the prospective US-based Health Professionals' Follow-up Study 1988-2007. We used spatiotemporal prediction models to estimate monthly PM less than 10 (PM10) and less than 2.5 (PM2.5), and PM2.5-10 at all mailing addresses. We used time-varying Cox proportional hazards models adjusted for potential confounders based on previous literature to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for each 10-μg/m3 increase in exposure in the preceding 1 and 12 months. We explored possible effect modification by age, obesity, smoking, aspirin use, diet quality, physical activity, diabetes, and Census region.

RESULTS

We observed 1,467 cases of incident stroke. Average levels of 12-month PM10, PM2.5-10, and PM2.5 were 20.7, 8.4, and 12.3 µg/m3, respectively. In multivariable adjusted models, we did not observe consistent associations between PM and overall or ischemic stroke. There was a suggestion of increased risk of hemorrhagic stroke (12-month PM10 multivariable HR: 1.13 [0.86, 1.48]; PM2.5-10: 1.12 [0.78, 1.62]; PM2.5:1.17 [0.76, 1.81], all per 10 µg/m3). There was little evidence of effect modification.

CONCLUSIONS

We observed only weak evidence of an association between long-term exposure to PM and risks of overall incident stroke. There was a suggestion of increasing hemorrhagic stroke risk.

Ambient air pollution and the risk of ischaemic and haemorrhagic stroke

Stroke is a leading cause of disability and the second most common cause of death worldwide. Increasing evidence suggests that air pollution is an emerging risk factor for stroke. Over the past decades, air pollution levels have continuously increased and are now estimated to be responsible for 14% of all stroke-associated deaths. Interpretation of previous literature is difficult because stroke was usually not distinguished as ischaemic or haemorrhagic, nor by cause. This Review summarises the evidence on the association between air pollution and the different causes of ischaemic stroke and haemorrhagic stroke, to clarify which people are most at risk. The risk for ischaemic stroke is increased after short-term or long-term exposure to air pollution. This effect is most pronounced in people with cardiovascular burden and stroke due to large artery disease or small vessel disease. Short-term exposure to air pollution increases the risk of intracerebral haemorrhage, a subtype of haemorrhagic stroke, whereas the effects of long-term exposure are less clear. Limitations of the current evidence are that studies are prone to misclassification of exposure, often rely on administrative data, and have insufficient clinical detail. In this Review, we provide an outlook on new research opportunities, such as those provided by the decreased levels of air pollution due to the current COVID-19 pandemic.

Association of Short-Term Particulate Matter Exposure among 5-Year Cancer Survivors with Incident Cardiovascular Disease: A Time-Stratified Case-Crossover Study

The association of short-term particulate matter concentration with cardiovascular disease (CVD) among cancer survivors is yet unclear. Using the National Health Insurance Service database from South Korea, the study population consisted of 22,864 5-year cancer survivors with CVD events during the period 2015-2018. Using a time-stratified case-crossover design, each case date (date of incident CVD) was matched with three or four referent dates, resulting in a total of 101,576 case and referent dates. The daily average particulate matter 10 (PM10), 2.5 (PM2.5), and 2.5-10 (PM2.5-10) on the day of case or referent date (lag0), 1-3 days before the case or referent date (lag1, lag2, and lag3), and the mean value 0-3 days before the case or referent date (lag0-3) were determined. Conditional logistic regression was conducted to calculate the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for CVD according to quartiles of PM10, PM2.5, and PM2.5-10. Compared to the 1st (lowest) quartile of lag0-3 PM10, the 4th (highest) quartile of lag0-3 PM10 was associated with higher odds for CVD (aOR 1.13, 95% CI 1.06-1.21). The 4th quartiles of lag1 (aOR 1.12, 95% CI 1.06-1.19), lag2 (aOR 1.09, 95% CI 1.03-1.16), lag3 (aOR 1.06, 95% CI 1.00-1.12), and lag0-3 (aOR 1.11, 95% CI 1.05-1.18) PM2.5 were associated with higher odds for CVD compared to the respective 1st quartiles. Similarly, the 4th quartile of lag0-3 PM2.5-10 was associated with higher CVD events (aOR 1.11, 95% CI 1.03-1.19) compared to the 1st quartile. Short-term exposure to high levels of PM may be associated with increased CVD risk among cancer survivors.

Acute effect of particulate matter pollution on hospital admissions for stroke among patients with type 2 diabetes in Beijing, China, from 2014 to 2018

BACKGROUND

The health effect of particulate matter pollution on stroke has been widely examined; however, the effect among patients with comorbid type 2 diabetes (T2D) in developing countries has remained largely unknown.

METHODS

A time-series study was conducted to investigate the short-term effect of fine particulate matter (PM_2.5) and inhalable particulate matter (PM₁₀) on hospital admissions for stroke among patients with T2D in Beijing, China, from 2014 to 2018. An over-dispersed Poisson generalized additive model was employed to adjust for important covariates, such as weather conditions and long-term and seasonal trends.

RESULTS

A total of 159,298 hospital admissions for stroke comorbid with T2D were reported. Approximately linear exposure-response curves were observed for PM_2.5 and PM₁₀ in relation to stroke admissions among T2D patients. A 10 μg/m³ increase in the four-day moving average of PM_2.5 and PM₁₀ was associated with 0.14% (95% confidence interval [CI]: 0.05-0.23%) and 0.14% (95% CI: 0.06-0.22%) incremental increases in stroke admissions among T2D patients, respectively. A 10 μg/m³ increase in PM_2.5 in the two-day moving average corresponded to a 0.72% (95% CI: 0.02-1.42%) incremental increase in hemorrhagic stroke, and a 10 μg/m³ increase in PM₁₀ in the four-day moving average corresponded to a 0.14% (95% CI: 0.06-0.22%) incremental increase in ischemic stroke.

CONCLUSIONS

High particulate matter might be a risk factor for stroke among patients with T2D. PM_2.5 and PM₁₀ have a linear exposure-response relationship with stroke among T2D patients. The study provided evidence of the risk of stroke due to particulate matter pollution among patients with comorbid T2D.

Health benefits of achieving fine particulate matter standards in India - A nationwide assessment

BACKGROUND

Ambient fine particulate matter (PM_2.5) is one of the leading risk factors in India. The elevated levels of PM_2.5 exposure concentration in India are related to higher premature mortality. However, health benefits or avoidable premature mortality by reducing PM_2.5 concentration is uncertain.

OBJECTIVES

Here we simulated the health benefits by assuming the achievement of 1) National Ambient Air Quality Standards of India (PM_2.5 annual average = 40 μg m^-3), 2) National Clean Air Programme policy (30% reduction) and 3) World Health Organization standard (10 μg m^-3).

METHODOLOGY

Using Environmental Benefits Mapping and Analysis Program - Community Edition (BenMAP-CE), the health benefits are estimated at national, state and district levels for various health endpoints viz., all-cause, ischaemic heart disease (IHD), chronic obstructive pulmonary disease (COPD), lung cancer and stroke. PM_2.5 data, concentration-response coefficient, population, and baseline incidence rate are specified as input data in BenMAP-CE.

RESULTS

At the national level, all-cause health benefits in three simulations range from 0.79 to 2.1 million cases during 2019. Similarly, IHD, COPD, lung cancer, and stroke related health benefits are in the range of 0.28-0.68, 0.17-0.39, 0.01-0.03, and 0.14-0.34 million cases, respectively. State-level estimates showed that Uttar Pradesh, Bihar, and West Bengal are having maximum health benefits whereas north-eastern states are found with lowest estimates. Districts such as Allahabad, Lucknow, Muzaffarpur, Patna, and Sultanpur are estimated to have highest health benefits. States and districts with higher PM_2.5 concentration and exposed population are found with maximum health benefits. Among the three simulations, achievement of the World Health Organization standard resulted in highest estimates. Further, the limitations and sensitivity of input parameters used in this study are discussed in detail.

CONCLUSION

Study results highlighted the need for state and district-specific air quality management measures to increase PM_2.5 related health benefits.

Prolonged Life Expectancy for Those Dying of Stroke by Achieving the Daily PM2.5 Targets

This time-series study collects data on stroke-related mortality, years of life lost (YLL), air pollution, and meteorological conditions in 96 Chinese cities from 2013 to 2016 and proposes a three-stage strategy to generate the national and regional estimations of avoidable YLL, gains in life expectancy and stroke-related population attributable fraction by postulating that the daily fine particulate matter (PM2.5) has been kept under certain standards. A total of 1 318 911 stroke deaths are analyzed. Each 10 µg m-3 increment in PM2.5 at lag03 is associated with a city-mean increase of 0.31 (95% CI: 0.19, 0.44) years of life lost from stroke. A number of 914.11 (95% CI: 538.28, 1288.94) years of city-mean life lost from stoke could be avoided by attaining the WHO's Air Quality Guidelines (AQG) (25 µg m-3). Moreover, by applying the AQG standard, 0.11 (0.08, 0.15) years of life lost might be prevented for each death, and about 0.91% (95% CI: 0.62%, 1.19%) of the total years of life lost from stroke might be explained by the daily excess PM2.5 exposure. This study indicates that stroke patients can have a longer life expectancy if stricter PM2.5 standards are put in place, especially ischemic stroke patients.

How longer can people live by achieving the daily ambient fine particulate pollution standards in the Pearl River Delta region, China?

BACKGROUND

Previous research has reported the effects of long-term fine particulate matter (PM_2.5) pollution on years of life lost (YLL), but these effects may not represent the full impact. This study aims to estimate potential benefits in life time from adhering to daily ambient PM_2.5 concentration standards/guidelines.

METHODS

This study evaluated the relationship between daily ambient PM_2.5 level and YLL using a two-stage approach with generalized additive models and meta-analysis. Potential life expectancy gains were then estimated by presuming that daily PM_2.5 levels were in compliance with the Chinese and WHO standards. In addition, the attributable fraction of YLL due to excess PM_2.5 exposure was also calculated.

RESULTS

During 2013-2016, 459,468 non-accidental deaths were recorded in the six cities of Pearl River Delta, China. Each 10 μg/m³ increment in four-day average (lag₀₃) level of PM_2.5 was related to an increment of 13.31 [95% confidence interval (CI): 5.74, 20.87] years of life lost. Implementation of the WHO guidelines might avoid 180,980.83 YLLs (95% CI: 78,116.07, 283,845.60), which corresponded to 0.39 (95% CI: 0.17, 0.62) years of increased life time per death. Additionally, an estimated 0.15% (95% CI: 0.06%, 0.23%) or 2.04% (95% CI: 0.88%, 3.20%) of YLLs could be attributed to PM_2.5 exposures higher than the Chinese or WHO guidelines, respectively.

CONCLUSIONS

This study suggests that people might live longer by controlling daily PM_2.5 concentration and highlights the need to adopt stricter standards in China.

Atomic Absorption Spectrometry Methods to Access the Metal Solubility of Aerosols in Artificial Lung Fluid

Recent studies to quantify the health risks that fine particulate matter with an aerodynamic less than 2.5 µm (PM_2.5) pose use in vitro approaches. One of these approaches is to incubate PM_2.5 in artificial lysosomal fluid for a given period at body temperature. These body fluids used have a high ionic strength and as such can be challenging samples to analyze with atomic spectroscopy techniques. As PM_2.5 is a primary health hazard because it is tiny enough to penetrate deep into the lungs and could, in addition, dissolve in the lung fluid it is important to quantify elements of toxic and/or carcinogenic concerns, reliably and accurately. Sophisticated instrumentation and expensive pre-treatment of challenging samples are not always available, especially in developing countries. To evaluate the applicability of graphite furnace atomic absorption spectrometry (GFAAS) without Zeeman correction capability to detect trace quantities of heavy metals leached from PM_2.5 on to artificial lung fluid, univariate and multivariate approaches have been used for optimization purposes. The limits of quantification, LOQ, obtained by the optimized method were: 2 µg L^-1 (Cu), 3 µg L^-1 (Cr), 1 µg L^-1 (Mn), and 10 µg L^-1 (Pb). The addition/recovery experiments had a mean accuracy of: (Cu) 99 ± 7%; 110 ± 8% (Cr); 95 ± 9% (Mn), and 96 ± 11% (Pb). The average soluble fractions of PM_2.5 incubated in artificial lysosomal fluid (ALF) for 1 h were: 1.2 ± 0.01 ng m^-3 Cu, 0.4 ± 0.01 ng m^-3 Cr, 0.6 ± 0.01 ng m^-3 Mn, and 4.8 ± 0.03 ng m^-3 Pb. Using historical elemental averages of PM_2.5 in Curitiba (Cu 3.3 ng m^-3, Cr 2.1 ng m^-3, Mn 6.1 ng m^-3, Pb 21 ng m^-3), the percentage bioaccessibility were determined to be Cu 38%, Cr 20%, Mn 10%, and Pb 23%. The elemental values of the atmospheric soluble fraction of Cu, Cr, and Mn were below the inhalation risk concentrations. However, for Pb, the atmospheric soluble fraction exceeded the inhalation unit risk of 0.012 ng m^-3. This robust and straightforward GF AAS method is pivotal for low and middle-income countries were most air pollution adverse effects occur and established lower-cost technologies are likely unavailable.

Ambient fine particulate matter and hospital admissions for ischemic and hemorrhagic strokes and transient ischemic attack in 248 Chinese cities

Few studies have investigated the acute effects of fine particulate matter (PM_2.5) on the risk of stroke subtypes and transient ischemic attack (TIA) in low- and middle-income countries. The primary aim of this study was to assess the associations between short-term exposure to PM_2.5 and daily hospital admissions for total cerebrovascular disease, ischemic and hemorrhagic strokes, and TIA in China. A total of 8,359,162 hospital admissions in 248 Chinese cities from 2013 to 2017 were identified from the Hospital Quality Monitoring System of China. Generalized additive models with quasi-Poisson regression were used to estimate the associations in each city, and random-effect meta-analyses were conducted to combine the city-specific estimates. We found that a 10 μg/m³ increase in PM_2.5 concentration was significantly associated with a 0.19% (95% CI, 0.13% to 0.25%), 0.26% (95% CI, 0.17% to 0.35%), and 0.26% (95% CI, 0.13% to 0.38%) increase in same-day hospital admissions for total cerebrovascular disease, ischemic stroke, and TIA, respectively. In contrast, a non-significant negative association with PM_2.5 was observed for hemorrhagic stroke in the main analyses (lag 0 day), which became statistically significant when using other single-day exposures (lag 1 or 2 days) or moving average exposures (lag 0-1, 0-2, or 0-3 days) as exposure metric. These associations were robust to adjustment for other criteria air pollutants in two-pollutant models. For ischemic stroke, the effect estimates were significantly larger in people aged 65-74 years, in cool season, and in cities with lower annual average PM_2.5 concentrations. The exposure-response curves were nonlinear with a leveling off at high concentrations. These results contribute to the relatively limited literature on the PM_2.5-related risks of cerebrovascular events in low- and middle-income countries.

Short-term associations between ambient air pollution and stroke hospitalisations: time-series study in Shenzhen, China

OBJECTIVE

To investigate the association between ambient air pollution and stroke morbidity in different subgroups and seasons.

METHODS

We performed a time-series analysis based on generalised linear models to study the short-term exposure-response relationships between air pollution and stroke hospitalisations, and conducted subgroup analyses to identify possible sensitive populations.

RESULTS

For every 10 µg/m³ increase in the concentration of air pollutants, across lag 0-3 days, the relative risk of stroke hospitalisation was 1.029 (95% CI 1.013 to 1.045) for PM_2.5, 1.054 (95% CI 1.031 to 1.077) for NO₂ and 1.012 (95% CI 1.002 to 1.022) for O₃. Subgroup analyses showed that statistically significant associations were found in both men and women, middle-aged and older populations, and both cerebral infarction and intracerebral haemorrhage. The seasonal analyses showed that statistically significant associations were found only in the winter.

CONCLUSIONS

Our study indicates that short-term exposure to PM_2.5, NO₂ and O₃ may induce stroke morbidity, and the government should take actions to mitigate air pollution and protect sensitive populations.

Short-term impacts of ambient fine particulate matter on emergency department visits: Comparative analysis of three exposure metrics

BACKGROUND

Research argued that daily excessive concentration hours (DECH) could be more informative through accounting for within-day variations, when assessing population-level exposure to ambient fine particle (PM_2.5). However, few studies have comparatively investigated PM_2.5-associated risks using DECH and two common metrics of daily mean and hourly peak concentration.

METHODS

We collected daily records of all-cause emergency department visits (EDVs) and hourly data on air pollutants and meteorological factors from Shenzhen, China, 2015-2018. According to guidelines proposed by the World Health Organization, DECH was calculated by summing up daily concentrations exceeding 25 μg/m³. Based on time-stratified case-crossover design, we adopted conditional logistic regression models to assess short-term attributable risks of EDVs associated with PM_2.5 using three exposure metrics.

RESULTS

DECH and daily average of PM_2.5 strongly elevated risks of EDVs, while less evident associations were observed using hourly peak metric. Estimated excess relative risks at lag 0 day were 0.56% (95% confidence interval [CI]: 0.21 to 0.91), 0.69% (95% CI: 0.25 to 1.13) and 0.37% (95% CI: 0.02 to 0.76), respectively, associated with an interquartile range increase in DECH (420.2 μg/m³), 24-h average (24.9 μg/m³) and hourly peak concentration (38 μg/m³). More emergency visits could be attributed to DECH than daily mean PM_2.5, with attributable fractions of 2.02% (95% CI: 1.42 to 2.61) and 1.09% (95% CI: 0.69 to 1.49), respectively.

CONCLUSIONS

This study added evidence for increased risk of EDVs associated with exposure to ambient PM_2.5. DECH was a potential alternative exposure metric for PM_2.5 assessment, which may have implications for future revision of air quality standards.

Correlation of α/γ-Fe2O3 nanoparticles with the toxicity of particulate matter originating from subway tunnels in Seoul stations, Korea

According to the increasing concern about particulate matter (PM) pollution at subway systems, particularly its potentially severe effects on human health, this study investigated the constituents, characteristics, and toxicity of PM collected at underground subway stations in Seoul, Korea. It was found that α/γ-Fe₂O₃ NPs, which are considered as thermal products derived from the brake-wheel-rail interface, were the main components of PM (57.6% and 48% of PM₁₀ and PM_2.5, respectively). In addition, hydrothermally synthesized α/γ-Fe₂O₃ NPs, proposing to possess similar properties to those of Fe₂O₃ contained in PM, were used to investigate the correlation of these oxides with PM toxicity. In particular, the synthesized γ-Fe₂O₃ NPs induced a negligibly toxic, while the synthesized α-Fe₂O₃ NPs and PM showed remarkably toxic effects on HeLa cells and zebrafish embryos, specifically in reducing cell proliferation to 85% and 72% survival, causing high apoptosis of 29.8% and 29.3%, and inhibiting the development of embryos up to 60% and 8% after prolonged exposure, respectively. It is considered that α-Fe₂O₃ NPs were primarily responsible for the harmful effects of PM, resulting in significant damage to DNA due to their capacity of producing high reactive oxygen species (ROS) and, thus, deleterious effects on the human body.

Association between rainfall and readmissions of rheumatoid arthritis patients: a time-stratified case-crossover analysis

It has been reported that local weather is associated with the symptoms of joint pain in patients with rheumatoid arthritis (RA), and many people believe their pain becomes worse when facing rainy days. However, limited studies explored the effects of weather on RA patients' healthcare-seeking behavior. Our study aimed to investigate the relationship between rainfall and readmission behavior of patients with RA in Hefei, China, based on hospitalization data from the First Affiliated Hospital of Anhui University of Chinese Medicine from May 2012 to June 2016 and weather data from National Meteorological Information Center during the same study period. Using a time-stratified case-crossover study design and conditional logistic regression, we found a negative association between current day rainfall and readmission (unadjusted: OR = 0.82, p < 0.05; adjusted: OR = 0.83, p < 0.1), which is contrary to our common belief. In lagged models, we observed that rainfall was significantly and positively associated with readmissions at lag 6 days (unadjusted: OR = 1.12, p < 0.1; adjusted: OR = 1.17, p < 0.05) and lag 7 days (unadjusted: OR = 1.13, p < 0.05; adjusted: OR = 1.21, p < 0.01). Additionally, stratified analyses showed the unanticipated finding was only statistically significant for younger patients (< 65 years) and females. Our study adds new evidence that the association between the healthcare-seeking behavior of patients with RA and local rainfall may be different, compared with the positive relationship between symptoms of joint pain and rainfall.

Effect of air pollution on hospitalization for acute exacerbation of chronic obstructive pulmonary disease, stroke, and myocardial infarction

This study aims to analyze the acute effects of PM_2.5, PM₁₀, SO₂, NO₂, and O₃ on hospitalizations for acute exacerbation of chronic obstructive pulmonary disease (AECOPD), stroke, and myocardial infarction (MI) from 2014 to 2017 in Shenyang, China. Hospitalization records for AECOPD (17,655), stroke (276,736) and MI (26,235) and air pollutions concentration data (PM_2.5, PM₁₀, SO₂, NO₂, and O₃) were collected. A generalized additive model (GAM) was utilized to determine the impact of air pollutants on the relative risk (RR) of hospitalization for AECOPD, stroke, and MI. Stratified analysis for AECOPD was based on gender and age. It was based on gender, age, hypertension, and diabetes for stroke, and for MI it was based on gender, age, and coronary atherosclerosis. The lag effect for AECOPD in terms of gender analysis occurred at lag3-lag5. The hospitalization risk for stroke with hypertension due to SO₂ and NO₂ was greater than that of stroke without hypertension. The risk of hospitalization for stroke with hypertension as a comorbidity due to O₃ was lower than without hypertension. The risk of hospitalization for MI combined with coronary atherosclerosis due to PM_2.5, PM₁₀, or NO₂ was higher than that of hospitalizations for MI without coronary atherosclerosis. Air pollution increased the rate of hospitalization for AECOPD. SO₂ and O₃ appeared protective for stroke patients with coronary atherosclerosis. PM_2.5, PM₁₀, and NO₂ had no influence on total hospitalization for myocardial infarction.

Short-term exposure to air pollution and incidence of stroke in the Women's Health Initiative

BACKGROUND

Evidence of the association between daily variation in air pollution and risk of stroke is inconsistent, potentially due to the heterogeneity in stroke etiology.

OBJECTIVES

To estimate the associations between daily variation in ambient air pollution and risk of stroke and its subtypes among participants of the Women's Health Initiative, a large prospective cohort study in the United States.

METHODS

We used national-scale, log-normal ordinary kriging models to estimate daily concentrations of fine particulate matter (PM2.5), respirable particulate matter (PM10), nitrogen dioxide (NO2), nitrogen oxides (NOx), sulphur dioxide, and ozone at participant addresses. Stroke was adjudicated by trained neurologists and classified as ischemic or hemorrhagic. Ischemic strokes were further classified according to the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification. We used a time-stratified case-crossover approach to estimate the odds ratio (OR) of the risk of stroke associated with an interquartile range (IQR) increase in concentrations of each air pollutant. We performed stratified analysis to examine whether associations varied across subgroups defined by age at stroke onset, US census region, smoking status, body mass index, and prior history of diabetes mellitus, hypertension, heart or circulation problems, or arterial fibrillation at enrollment.

RESULTS

Among 5417 confirmed strokes between 1993 and 2012, 4300 (79.4%) were classified as ischemic and 924 (17.1%) as hemorrhagic. No association was observed between day-to-day variation in any pollutant and risk of total stroke, ischemic stroke, or specific etiologies of ischemic stroke. We observed a positive association between risk of hemorrhagic stroke and NO2 and NOx in the 3 days prior to stroke with OR of 1.24 (95% CI: 1.01, 1.52) and 1.18 (95% CI: 1.03, 1.34) per IQR increase, respectively. The observed associations with hemorrhagic stroke were more pronounced among non-obese participants.

CONCLUSIONS

In this large cohort of post-menopausal US women, daily NO2 and NOx were associated with higher risk of hemorrhagic stroke, but ambient levels of four other air pollutants were not associated with higher risk of total stroke, ischemic stroke, or ischemic stroke subtypes.