Gaseous Air Pollution and the Risk for Stroke Admissions: A Case-Crossover Study in Beijing, China

Estimating the short-term effect of PM2.5 on the mortality of cardiovascular diseases based on instrumental variables

BACKGROUND

PM2.5 can induce and aggravate the occurrence and development of cardiovascular diseases (CVDs). The objective of our study is to estimate the causal effect of PM2.5 on mortality rates associated with CVDs using the instrumental variables (IVs) method.

METHODS

We extracted daily meteorological, PM2.5 and CVDs death data from 2016 to 2020 in Binzhou. Subsequently, we employed the general additive model (GAM), two-stage predictor substitution (2SPS), and control function (CFN) to analyze the association between PM2.5 and daily CVDs mortality.

RESULTS

The 2SPS estimated the association between PM2.5 and daily CVDs mortality as 1.14% (95% CI: 1.04%, 1.14%) for every 10 µg/m3 increase in PM2.5. Meanwhile, the CFN estimated this association to be 1.05% (95% CI: 1.02%, 1.10%). The GAM estimated it as 0.85% (95% CI: 0.77%, 1.05%). PM2.5 also exhibited a statistically significant effect on the mortality rate of patients with ischaemic heart disease, myocardial infarction, or cerebrovascular accidents (P < 0.05). However, no significant association was observed between PM2.5 and hypertension.

CONCLUSION

PM2.5 was significantly associated with daily CVDs deaths (excluding hypertension). The estimates from the IVs method were slightly higher than those from the GAM. Previous studies based on GAM may have underestimated the impact of PM2.5 on CVDs.

Effects of sulfur dioxide inhalation on human health: a review

Sulfur dioxide (SO2) is one of the most important gaseous air pollutants and the chemical index of sulfur oxides (SOx). SO2 is one of the six criteria pollutants in the air quality index (AQI). SO2 can be emitted by natural and anthropogenic sources. Although efforts have been made to reduce sulfur dioxide emissions worldwide, this pollutant and its adverse effects remain a major concern, especially in developing countries. The aim of this study was the investigated the effects of sulfur dioxide inhalation on human health. This narrative review was done based on the literature published from 2000 to 2022 through PubMed, Springer, Web of Science, Science Direct, and Google Scholar databases. In this study, was done screened first based on the abstract and Final assessment done based on the full text of the article. Finally, 38 articles were selected for inclusion in the study. The results of this study showed that sulfur dioxide has adverse health effects on the human respiratory, cardiovascular, and nervous systems and causes type 2 diabetes and non-accidental deaths. Although some evidence suggests that sulfur dioxide in given concentrations has no adverse health effect, its synergistic effects in combination with other air pollutants may be significant. Among the most important practical results of this study can be mentioned to increase the health awareness of the general public, help the politicians of the health sector in making decisions in the health field, creating awareness among polluting producing units and industries and efforts to reduce the emission of Sulfur dioxide.

Short-Term Exposure to Air Pollution and the Incidence and Mortality of Stroke: A Meta-Analysis

BACKGROUND

The relationship between short-term exposure to various air pollutants [particulate matter <10 μm (PM 10 ), particulate matter <2.5 μm (PM 2.5 ), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), carbon monoxide, and ozone (O 3 )] and the incidence and mortality of stroke remain unclear.

REVIEW SUMMARY

We conducted a comprehensive search across databases, including PubMed, Web of Science, and others. A random-effects model was employed to estimate the odds ratios (OR) and their 95% CIs. Short-term exposure to PM 10 , PM 2.5 , NO 2 , SO 2 , and O 3 was associated with increased stroke incidence [per 10 μg/m 3 increase in PM 2.5 : OR = 1.005 (95% CI: 1.004-1.007), per 10 μg/m 3 increase in PM 10 : OR = 1.006 (95% CI: 1.004-1.009), per 10 μg/m 3 increase in SO 2 : OR = 1.034 (95% CI: 1.020-1.048), per 10 μg/m 3 increase in NO 2 : OR = 1.029 (95% CI: 1.015-1.043), and O 3 for per 10 μg/m 3 increase: OR: 1.006 (95% CI: 1.004-1.007)]. In addition, short-term exposure to PM 2.5 , PM 10 , SO 2, and NO 2 was correlated with increased mortality from stroke [per 10 μg/m 3 increase in PM 2.5 : OR = 1.010 (95% CI: 1.006-1.013), per 10 μg/m 3 increase in PM 10 : OR = 1.004 (95% CI: 1.003-1.006), per 10 μg/m 3 increase in SO 2 : OR = 1.013 (95% CI: 1.007-1.019) and per 10 μg/m 3 increase in NO 2 : OR = 1.012 (95% CI: 1.008-1.015)].

CONCLUSION

Reducing outdoor air pollutant levels may yield a favorable outcome in reducing the incidence and mortality associated with strokes.

Short-term effects of ambient oxidation, and its interaction with fine particles on first-ever stroke: A national case-crossover study in China

Stroke is a significant global cause of disability and death, and its burden has been on the rise, while ambient air pollution has been conclusively linked to stroke incidence. However, knowledge about effects of atmospheric oxidation on stroke and its interactions with fine particles (PM2.5) are still limited. In this study, we investigated the short-term effects of ambient NO2, O3, and their combined oxidation (Owt) on first-ever stroke, based on data from the China National Stroke Screening Survey (CNSSS) conducted from 2013 to 2015. We found significant association between ambient NO2 exposure at lag0 day with first-ever stroke, with a 13.1 % (95 % CI: 3.5 %, 23.6 %) increase in the first-ever stroke risk per 10 μg/m3 exposure. We also found a significant interaction between NO2 and PM2.5 (p < 0.05): first-ever stroke risk increased 23.8 % (95 % CI: 9.6 %, 39.8 %) per 10 μg/m3 NO2 exposure in population exposed to higher PM2.5 concentrations, while no significant association was found in population exposed to lower PM2.5 concentrations. The results of stratified analyses indicated that physical inactivity enhanced the detrimental effects of O3 and Owt exposure, while smoking and transient ischemic attack (TIA) history enhanced the detrimental effects of NO2 exposure. However, TIA history appeared to mitigate the adverse effects of O3 exposure. This study is helpful to better understand the impact of ambient oxidation on stroke, as well as its interaction with PM2.5, and has implications for policies and standards for atmospheric protection and governance.

Short-Term Exposure to Ambient Air Pollution and Influenza: A Multicity Study in China

BACKGROUND

Air pollution is a major risk factor for planetary health and has long been suspected of predisposing humans to respiratory diseases induced by pathogens like influenza viruses. However, epidemiological evidence remains elusive due to lack of longitudinal data from large cohorts.

OBJECTIVE

Our aim is to quantify the short-term association of influenza incidence with exposure to ambient air pollutants in Chinese cities.

METHODS

Based on air pollutant data and influenza surveillance data from 82 cities in China over a period of 5 years, we applied a two-stage time series analysis to assess the association of daily incidence of reported influenza cases with six common air pollutants [particulate matter with aerodynamic diameter ≤ 2.5 μ m (PM 2.5 ), particulate matter with aerodynamic diameter ≤ 10 μ m (PM 10 ), NO 2 , SO 2 , CO, and O 3 ], while adjusting for potential confounders including temperature, relative humidity, seasonality, and holiday effects. We built a distributed lag Poisson model for one or multiple pollutants in each individual city in the first stage and conducted a meta-analysis to pool city-specific estimates in the second stage.

RESULTS

A total of 3,735,934 influenza cases were reported in 82 cities from 2015 to 2019, accounting for 72.71% of the overall case number reported in the mainland of China. The time series models for each pollutant alone showed that the daily incidence of reported influenza cases was positively associated with almost all air pollutants except for ozone. The most prominent short-term associations were found for SO 2 and NO 2 with cumulative risk ratios of 1.094 [95% confidence interval (CI): 1.054, 1.136] and 1.093 (95% CI: 1.067, 1.119), respectively, for each 10   μ g / m 3 increase in the concentration at each of the lags of 1-7 d. Only NO 2 showed a significant association with the daily incidence of influenza cases in the multipollutant model that adjusts all six air pollutants together. The impact of air pollutants on influenza was generally found to be greater in children, in subtropical cities, and during cold months.

DISCUSSION

Increased exposure to ambient air pollutants, particularly NO 2 , is associated with a higher risk of influenza-associated illness. Policies on reducing air pollution levels may help alleviate the disease burden due to influenza infection. https://doi.org/10.1289/EHP12146.

Air Pollution and Its Adverse Effects on the Central Nervous System

Air pollution is recognized as a significant public health problem and is associated with illnesses of the central nervous system (CNS) as well as neuroinflammation and neuropathology. Air pollution may cause chronic brain inflammation, white matter abnormalities, and microglia activation, which increases the risk of autism spectrum disorders, neurodegenerative disorders, stroke, and multiple sclerosis (MS). Methods: A literature review was done on "PubMed, EMBASE and Web of Science" on the relationship of air pollution with MS and stroke, using the keywords "air pollution" OR "pollution"; "ambient air pollution," "particulate matter, ozone, black carbon" AND "stroke" OR "cerebrovascular diseases," "multiple sclerosis," "neuroinflammation," or "neurodegeneration." Results: We first identified 128 articles and their related websites, of which 44 articles were further selected for analysis mainly based on study relevance, study quality and reliability, and date of publication. Further studies on air pollution and its adverse effects on the CNS are needed. The findings of such studies will support the development of appropriate preventive measures in the future.

The association between short-term ambient sulfur dioxide exposure and hospitalization costs of ischemic stroke: a hospital-based study in Chongqing, China

Evidence of the short-term effects of ambient sulfur dioxide (SO₂) exposure on the economic burden of ischemic stroke is limited. This study aimed to explore the association between short-term ambient SO₂ exposure and hospitalization costs for ischemic stroke in Chongqing, the most populous city in China. The hospital-based study included 7271 ischemic stroke inpatients. Multiple linear regression models were used to estimate the association between SO₂ concentration and hospitalization costs. Propensity score matching was used to compare the patients' characteristics when exposed to SO₂ concentrations above and below 20 μg/m³. It is found that short-term SO₂ exposure was positively correlated with the hospitalization costs of ischemic stroke. The association was more evident in males, people younger than 65, and people hospitalized in the cool seasons. Besides, among the components of hospitalization costs, medicine costs were most significantly associated with SO₂. More interesting, the lower concentration of SO₂, the higher costs associated with 1 μg/m³ SO₂ change. Above all, SO₂ was positively associated with hospitalization costs of ischemic stroke, even at its low levels. The measures to reduce the level of SO₂ can help reduce the burden of ischemic stroke.

Associations between short-term exposure to ambient PM2.5 and incident cases of cerebrovascular disease in Yantai, China

There are limited studies examining the association between PM_2.5 exposure and incident cerebrovascular disease (CD) cases in China. In this study, daily counts of incident CD cases and daily PM_2.5 concentrations were obtained in Yantai, Shandong Province, China from 2014 to 2019. We used a combination of the Poisson-distribution generalized linear model (GLM) and a distributed lag nonlinear model (DLNM) to examine the association of short-term exposure to ambient PM_2.5 and incident cases of CD. The results revealed that for every 10 μg/m³ increment of PM_2.5 would increase the incident CD cases by 0.216% (RR:1.00216, 95%CI:1.0016-1.0028) at lag4. The stratified analysis demonstrated that the females and residents aged 65 years or above presented higher short-term PM_2.5-associated CD risks than the males and aged below 65 years. Targeted prevention strategies should be adopted to reduce the PM_2.5-related CD burden, especially for the susceptible population in China.

Short-term associations of ambient air pollution with hospital admissions for ischemic stroke in 97 Japanese cities

The short-term association between ambient air pollution and hospital admissions for ischemic stroke is not fully understood. We examined the association between four regularly measured major ambient air pollutants, i.e., sulfur dioxide (SO₂), nitrogen dioxide (NO₂), photochemical oxidants (O_x), and particulate matter with aerodynamic diameters ≤ 2.5 μm (PM_2.5), and hospital admissions for ischemic stroke by analyzing 3 years of nationwide claims data from 97 cities in Japan. We first estimated city-specific results by using generalized additive models with a quasi-Poisson regression, and we obtained the national average by combining city-specific results with the use of random-effect models. We identified a total of 335,248 hospital admissions for ischemic stroke during the 3-year period. Our analysis results demonstrated that interquartile range increases in the following four ambient air pollutants were significantly associated with hospital admissions for ischemic stroke on the same day: SO₂ (1.05 ppb), 1.05% (95% CI: 0.59-1.50%); NO₂ (6.40 ppb), 1.10% (95% CI: 0.61-1.59%); O_x (18.32 ppb), 1.43% (95% CI: 0.81-2.06%); and PM_2.5 (7.86 μg/m³), 0.90% (95% CI: 0.35-1.45%). When the data were stratified by the hospital admittees' medication use, we observed stronger associations with SO₂, NO₂, and PM_2.5 among the patients who were taking antihypertensive drugs and weaker associations with SO₂, NO₂, and O_x among those taking antiplatelet drugs. Short-term exposure to ambient air pollution was associated with increased hospital admissions for ischemic stroke, and medication use and season may modify the association.

Short-Term Effects of Low-Level Ambient Air NO2 on the Risk of Incident Stroke in Enshi City, China

Previous studies found that exposure to ambient nitrogen dioxide (NO₂) was associated with an increased risk of incident stroke, but few studies have been conducted for relatively low NO₂ pollution areas. In this study, the short-term effects of NO₂ on the risk of incident stroke in a relatively low-pollution area, Enshi city of Hubei Province, China, were investigated through time-series analysis. Daily air-pollution data, meteorological data, and stroke incidence data of residents in Enshi city from 1 January 2015 to 31 December 2018 were collected. A time-series analysis using a generalised additive model (GAM) based on Poisson distribution was applied to explore the short-term effects of low-level NO₂ exposure on the risk of incident stroke and stroke subtypes, as well as possible age, sex, and seasonal differences behind the effects. In the GAM model, potential confounding factors, such as public holidays, day of the week, long-term trends, and meteorological factors (temperature and relative humidity), were controlled. A total of 9122 stroke incident cases were included during the study period. We found that NO₂ had statistically significant effects on the incidence of stroke and ischemic stroke, estimated by excess risk (ER) of 0.37% (95% CI: 0.04–0.70%) and 0.58% (95% CI: 0.18–0.98%), respectively. For the cumulative lag effects, the NO₂ still had a statistically significant effect on incident ischemic stroke, estimated by ER of 0.61% (95% CI: 0.01–1.21%). The two-pollutant model showed that the effects of NO₂ on incident total stroke were still statistically significant after adjusting for other air pollutants (PM_2.5, PM₁₀, SO₂, CO, and O₃). In addition, the effects of NO₂ exposure on incident stroke were statistically significant in elderly (ER = 0.75%; 95% CI: 0.11–1.40%), males (ER = 0.47%; 95% CI: 0.05–0.89%) and cold season (ER = 0.83%; 95% CI: 0.15–1.51%) subgroups. Our study showed that, as commonly observed in high-pollution areas, short-term exposure to low-level NO₂ was associated with an increased risk of incident stroke, including ischemic stroke. Males and elderly people were more vulnerable to the effects of NO₂, and the adverse effects might be promoted in the cold season.

Acute Effects of Air Pollution on Ischemic Heart Disease Hospitalizations: A Population-Based Time-Series Study in Wuhan, China, 2017-2018

Evidence of the acute effects of air pollutants on ischemic heart disease (IHD) hospitalizations based on the entire population of a megacity in central China is lacking. All IHD hospitalization records from 2017 to 2018 were obtained from the Wuhan Information Center of Health and Family Planning. Daily air pollutant concentrations and meteorological data were synchronously collected from the Wuhan Environmental Protection Bureau. A time-series study using generalized additive models was conducted to systematically examine the associations between air pollutants and IHD hospitalizations. Stratified analyses by gender, age, season, hypertension, diabetes, and hyperlipidemia were performed. In total, 139,616 IHD hospitalizations were included. Short-term exposure to air pollutants was positively associated with IHD hospitalizations. The age group ≥76 was at higher exposure risk, and the associations appeared to be more evident in cold seasons. PM2.5 and PM10 appeared to have greater effects on males and those without hypertension or diabetes, whereas NO2 and SO2 had greater effects on females and those with hypertension or diabetes. The risk of IHD hospitalization due to air pollutants was greater in people without hyperlipidemia. Our study provides new evidence of the effects of air pollution on the increased incidence of IHD in central China.

Short-Term Association of Air Pollutant Levels and Hospital Admissions for Stroke and Effect Modification by Apparent Temperature: Evidence From Shanghai, China

The epidemiological evidence on relationships between air pollution, temperature, and stroke remains inconclusive. Limited evidence is available for the effect modification by apparent temperature, an indicator reflecting reactions to the thermal environment, on short-term associations between air pollution and hospital admissions for stroke. We used a generalized additive model with Poisson regression to estimate the relative risk (RR) of stroke admissions in Shanghai, China, between 2014 and 2016 associated with air pollutants, with subgroup analyses by age, sex, apparent temperature, and season. During the study period, changes in the daily number of stroke admissions per 10 μg/m³ increase in nitrogen dioxide (at lags 0, 1, 0–1, and 0–2) ranged from 1.05 (95% CI: 0.82%, 2.88%) to 2.24% (95% CI: 0.84%, 3.65%). For each 10 μg/m³ increase in sulfur dioxide concentrations at lags 1, 2, 0–1, and 0–2, the RR of daily stroke admissions increased by 3.34 (95% CI: 0.955%, 5.79%), 0.32 (95% CI: −1.97%, 2.67%), 3.33 (95% CI: 0.38%, 6.37%), and 2.86% (95% CI: −0.45%, 6.28%), respectively. The associations of same-day exposure to nitrogen dioxide with stroke admissions remained significant after adjustment for ozone levels. These associations were not modified by sex, age, apparent temperature, or season. More research is warranted to determine whether apparent temperature modifies the associations between air pollution and stroke admissions.

Ambient air pollution and cerebrovascular disease mortality: an ecological time-series study based on 7-year death records in central China

Most studies of short-term exposure to ambient air pollution and cerebrovascular diseases focused on specific stroke-related outcomes, and results were inconsistent due to data unavailability and limited sample size. It is unclear yet how ambient air pollution contributes to the total cardiovascular mortality in central China. Daily deaths from cerebrovascular diseases were obtained from the Disease Surveillance Point System (DSPs) of Wuhan Center for Disease Control and Prevention during the period from 2013 to 2019. Air pollution data were obtained from Wuhan Ecology and Environment Institute from 10 national air quality monitoring stations, including average daily PM_2.5, PM₁₀, SO₂, NO₂, and O₃. Average daily temperature and relative humidity were obtained from Wuhan Meteorological Bureau. We performed a Poisson regression in generalized additive models (GAM) to examine the association between ambient air pollution and cerebrovascular disease mortality. We observed a total of 84,811 deaths from cerebrovascular diseases from 1 January 2013 to 31 December 2019 in Wuhan. Short-term exposure to PM_2.5, PM₁₀, SO₂, and NO₂ was positively associated with daily deaths from cerebrovascular diseases, and no significant association was found for O₃. The largest effect on cerebrovascular disease mortality was found at lag0 for PM_2.5 (ERR: 0.927, 95% CI: 0.749-1.105 per 10 μg/m3) and lag1 for PM₁₀ (ERR: 0.627, 95% CI: 0.493-0.761 per 10 μg/m³), SO₂ (ERR: 2.518, 95% CI: 1.914, 3.122 per 10 μg/m³), and NO₂ (ERR: 1.090, 95% CI: 0.822-1.358 per 10 μg/m³). The trends across lags were statistically significant. The stratified analysis demonstrated that females were more susceptible to SO₂ and NO₂, while elder individuals aged above 65 years old, compared with younger people, suffered more from air pollution, especially from SO₂. Short-term exposure to PM_2.5, PM₁₀, SO₂, and NO₂ were significantly associated with a higher risk of cerebrovascular disease mortality, and elder females seemed to suffer more from air pollution. Further research is required to reveal the underlying mechanisms.

Neurological disorders vis-à-vis climate change

Climate change is one of the biggest challenges humanity is facing in the 21st century. Two recognized sequelae of climate change are global warming and air pollution. The gradual increase in ambient temperature, coupled with elevated pollution levels have a devastating effect on our health, potentially contributing to the increased rate and severity of numerous neurological disorders. The main aim of this review paper is to shed some light on the association between the phenomena of global warming and air pollution, and two of the most common and debilitating neurological conditions: stroke and neurodegenerative disorders. Extreme ambient temperatures induce neurological impairment and increase stroke incidence and mortality. Global warming does not participate in the etiology of neurodegenerative disorders, but it exacerbates symptoms of dementia, Alzheimer's disease (AD) and Parkinson's Disease (PD). A very close link exists between accumulated levels of air pollutants (principally particulate matter), and the incidence of ischemic rather than hemorrhagic strokes. People exposed to air pollutants have a higher risk of developing dementia and AD, but not PD. Oxidative stress, changes in cardiovascular and cerebrovascular haemodynamics, excitotoxicity, microglial activation, and cellular apoptosis, all play a central role in the overlap of the effect of climate change on neurological disorders. The complex interactions between global warming and air pollution, and their intricate effect on the nervous system, imply that future policies aimed to mitigate climate change must address these two challenges in unison.

Association between exposure to ambient air pollution and hospital admission, incidence, and mortality of stroke: an updated systematic review and meta-analysis of more than 23 million participants

BACKGROUND

Previous studies have suggested that exposure to air pollution may increase stroke risk, but the results remain inconsistent. Evidence of more recent studies is highly warranted, especially gas air pollutants.

METHODS

We searched PubMed, Embase, and Web of Science to identify studies till February 2020 and conducted a meta-analysis on the association between air pollution (PM_2.5, particulate matter with aerodynamic diameter less than 2.5 μm; PM₁₀, particulate matter with aerodynamic diameter less than 10 μm; NO₂, nitrogen dioxide; SO₂, sulfur dioxide; CO, carbon monoxide; O₃, ozone) and stroke (hospital admission, incidence, and mortality). Fixed- or random-effects model was used to calculate pooled odds ratios (OR)/hazard ratio (HR) and their 95% confidence intervals (CI) for a 10 μg/m³ increase in air pollutant concentration.

RESULTS

A total of 68 studies conducted from more than 23 million participants were included in our meta-analysis. Meta-analyses showed significant associations of all six air pollutants and stroke hospital admission (e.g., PM_2.5: OR = 1.008 (95% CI 1.005, 1.011); NO₂: OR = 1.023 (95% CI 1.015, 1.030), per 10 μg/m³ increases in air pollutant concentration). Exposure to PM_2.5, SO₂, and NO₂ was associated with increased risks of stroke incidence (PM_2.5: HR = 1.048 (95% CI 1.020, 1.076); SO₂: HR = 1.002 (95% CI 1.000, 1.003); NO₂: HR = 1.002 (95% CI 1.000, 1.003), respectively). However, no significant differences were found in associations of PM₁₀, CO, O₃, and stroke incidence. Except for CO and O₃, we found that higher level of air pollution (PM_2.5, PM₁₀, SO₂, and NO₂) exposure was associated with higher stroke mortality (e.g., PM₁₀: OR = 1.006 (95% CI 1.003, 1.010), SO₂: OR = 1.006 (95% CI 1.005, 1.008).

CONCLUSIONS

Exposure to air pollution was positively associated with an increased risk of stroke hospital admission (PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃), incidence (PM_2.5, SO₂, and NO₂), and mortality (PM_2.5, PM₁₀, SO₂, and NO₂). Our study would provide a more comprehensive evidence of air pollution and stroke, especially SO₂ and NO₂.

Association of exhaled carbon monoxide with risk of cardio-cerebral-vascular disease in the China Kadoorie Biobank cohort study

Exhaled carbon monoxide (COex) level has been proposed as a noninvasive and easily-obtainable cardiovascular risk marker, however, with limited prospective evidence, and its association with stroke risk has been rarely explored. Measurements of COex were performed during 2004-2008 baseline examinations in the China Kadoorie Biobank study among 512,891 adults aged 30-79 years from 10 diverse study areas. After excluding participants with baseline cardiopulmonary diseases, stroke and cancer, 178,485 men and 267,202 women remained. Cox regression yielded hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of cardio-cerebral-vascular disease (CCVD) associated with COex levels, with sequential addition of adjustment for proxy variables for CO exposure, including study area indexing ambient CO variations at large, and smoking and solid fuel use, apart from adjusting for traditional cardiovascular risk factors. During 7-year follow-up, we documented 1744 and 1430 major coronary events (myocardial infarction plus fatal ischemic heart disease), 8849 and 10,922 ischemic strokes, and 2492 and 2363 hemorrhagic strokes among men and women, respectively. The HRs with 95% CIs comparing the highest with lowest COex quintile were 2.15 [1.72, 2.69] for major coronary events, 1.65 [1.50, 1.80] for ischemic stroke, and 1.35 [1.13, 1.61] for hemorrhagic stroke among men, while among women higher associated risk was only observed for major coronary events (1.64 [1.35, 2.00]) and ischemic stroke (1.87 [1.73, 2.01]). The elevated risks were consistent when COex level was over 3 ppm. However, these associations were all attenuated until null by sequential addition of stratification by study areas, and adjustments of smoking and solid fuel use. Nevertheless, the association with ischemic stroke was maintained among the subgroup of male smokers even with adjustment for the depth and amount of cigarette smoking (HR [95% CI]: 1.37 [1.06, 1.77]), while a negative association with hemorrhagic stroke also appeared within this subgroup. Higher COex level (over 3 ppm) was associated with elevated risk of ischemic CCVD, but not independently of CO exposure. Our finding suggests that, though not an independent risk factor, COex could potentially provide a cost-effective biomarker for ischemic cardio-cerebral-vascular risk, given that CO exposure is ubiquitous.

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.

Hourly associations between ambient air pollution and emergency ambulance calls in one central Chinese city: Implications for hourly air quality standards

BACKGROUND

Most studies on the short-term health effects of air pollution have been conducted on a daily time scale, while hourly associations remain unclear.

METHODS

We collected the hourly data of emergency ambulance calls (EACs), ambient air pollution, and meteorological variables from 2014 to 2016 in Luoyang, a central Chinese city in Henan Province. We used a generalized additive model to estimate the hourly effects of ambient air pollutants (PM_2.5, PM₁₀, SO₂, and NO₂) on EACs for all natural causes and cardiovascular and respiratory morbidity, with adjustment for potential confounding factors. We further examined the effect modification by temperature, relative humidity, wind speed, and atmospheric pressure using stratified analyses.

RESULTS

In the single-pollutant models, PM_2.5, PM₁₀, SO₂, and NO₂ were associated with an immediate increase in all-cause morbidity at 0, 0, 12, 10 h, separately, after exposure to these pollutants (excess risks: 0.19% (95% confidence interval (CI): 0.03%, 0.35%), 0.13% (95% CI: 0.02%, 0.24%), 0.28% (95% CI: 0.01%, 0.54%) and 0.52% (95% CI: 0.06%, 0.99%), respectively). These effects remained generally stable in two-pollutant models. SO₂ and NO₂ were significantly associated with an immediate increase in risk of cardiovascular morbidity, but the effects on respiratory morbidity were relatively more delayed. The stratified analyses suggested that temperature could modify the association between PM_2.5 and EACs, humidity and atmospheric pressure could modify the association between SO₂ and EACs.

CONCLUSIONS

Our study provides new evidence that higher concentrations of PM_2.5, PM₁₀, SO₂, and NO₂ may have transiently acute effects on all-cause morbidity and subacute effects on respiratory morbidity. SO₂ and NO₂ may also have immediate effects on cardiovascular morbidity. Findings of this study have important implications for the formation of hourly air quality standards.

Acute effects of air pollutants on daily mortality and hospitalizations due to cardiovascular and respiratory diseases

Background

Chiang Dao is one of the districts in Chiang Mai, Thailand facing high level of seasonal air pollution every year, the exposure of community dwellers to outdoor air pollutants 24 hours a day during seasonal smog period because of their open-air housing style, and agricultural occupational hazard. In addition, Chiang Dao hospital is the only available hospital serving the community with open-air wards; therefore we could certainly to identify the association between air pollution and mortality of hospitalized patients. Thus, the aim of this study was to determine the association between daily average seasonal air pollutants and daily mortality of hospitalized patients and community dwellers as well as emergency and hospitalization visits for serious respiratory, cardiovascular, and cerebrovascular diseases.

Methods

This time series study was conducted between 1 March 2016 and 31 March 2017. The association of various air pollutant concentrations including particulate matter diameter less than 10 and 2.5 microns (PM₁₀ and PM_2.5), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), ozone (O₃) and daily mortality of hospitalized patients and community dwellers as well as relationship with frequencies of serious respiratory, cardiovascular, and cerebrovascular diseases were analyzed using a general linear model with Poisson distribution.

Results

Only PM_2.5 was found to be associated with increased daily mortality of hospitalized patients (lag day 6, adjusted RR =1.153, 95% CI: 1.001-1.329), whereas PM₁₀, PM_2.5, NO₂, and O₃ were associated with increased daily non-accidental mortality of community dwellers (lag day 0-7, adjusted RR =1.006-1.040, 95% CI: 1.000-1.074). For acute serious respiratory events; PM₁₀ and PM_2.5 were associated with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), while SO₂, CO, and O₃ were associated with emergency visits for community-acquired pneumonia (CAP). O₃ was associated with emergency visits for heart failure (HF), NO₂ with emergency visits for myocardial infarction (MI), and SO₂ with hospitalized visits for cerebrovascular accident (CVA).

Conclusions

Seasonal air pollutants were found to be associated with higher mortality among hospitalized patients and community dwellers with varying effects on severe acute respiratory, cardiovascular, and cerebrovascular diseases.

The effect of air pollution on hospitalization of individuals with respiratory and cardiovascular diseases in Jinan, China

To analyze the short-term effects of air pollution on the hospitalization rates of individuals with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), stroke, and myocardial infarction (MI) after adjusting for confounding factors including weather, day of the week, holidays, and long-term trends in Jinan, China.Hospitalization information was extracted based on data from the primary class 3-A hospitals in Jinan from 2013 to 2015. The concentrations of PM2.5, PM10, SO2, NO2, and O3 were obtained from Jinan Environment Monitoring Center. The relative risk and 95% confidence intervals of AECOPD, stroke, and MI were estimated using generalized additive models with quasi-Poisson distribution in the mgcv package, using R software, version 1.0.136.The incremental increased concentrations of particulate pollutants including PM2.5 and PM10 were significantly associated with increased risk of hospitalization of AECOPD, stroke, and MI, and the adverse influences of PM2.5 on these diseases were generally stronger than that of PM10. The incremental increased concentrations of gaseous pollutants including SO2, NO2, and O3 were significantly associated with increased risk of hospitalization of stroke and MI in this population.Air pollution has significant adverse effects on hospitalization rates of individuals with AECOPD, stroke, and MI in Jinan, China.

Is breathing our polluted air a risk factor for stroke?

The conference "Climate change, air pollution and health" was held at the Pontifical Academy of Sciences. The data presented highlighted that air pollution is a major, under-recognized and modifiable risk factor for stroke and heart disease. Air pollution causes 7.6% of all deaths making it the fifth cause of death globally, and this figure is expected to increase by 50% by 2050. Particulate matter causes endothelial dysfunction and induces thrombosis by altering reactive oxygen species, nitric oxide, insulin resistance, and lipid levels. Thirty-three articles published since 2002 were reviewed to assess the relation between air pollution and stroke with age, geographical location, particulate and gaseous matter type, duration of exposure, previous stroke, and comorbidities. It remains to be defined if air pollution has pathophysiological effects that preferentially predispose individuals to ischemic or hemorrhagic stroke. There is ample evidence showing an association between acute and chronic exposure to PM_2.5 or gaseous pollutants with stroke. This potentially avoidable scenario and its dramatic consequences are heavily under-recognized by health professionals and the wider public. Preventive measures in people at high vascular risk are warranted. Procrastination in implementing efforts to stop the current worldwide course of worsening air pollution is the seed of a potential global health catastrophe.

A national case-crossover study on ambient ozone pollution and first-ever stroke among Chinese adults: Interpreting a weak association via differential susceptibility

Evidence suggesting an association between ozone exposure and stroke risk remains inconsistent; variations in the distributions of susceptibilities of the study populations may explain some of it. We examined the hypothesis in a general Chinese population. During 2013-2015, 1356 first-ever stroke events were selected from a large representative sample, the China National Stroke Screening Survey (CNSSS) database; daily maximal 8-hour ozone concentrations were obtained from spatiotemporally interpolated estimates of in-situ observations over China. We conducted a time-stratified case-crossover design to assess associations between stroke risk and ambient ozone exposure. Next, potential effect modifiers were identified using interaction analyses. Final, a well-established approach was applied to estimate individual-level susceptibility (i.e., the individual-specific effect given a certain combination of multiple effect-modifiers) and its probability distribution among all the CNSSS participants (n = 1,292,010). With adjustments for temperature, relative humidity and ambient fine particulate matter exposure, a 10-μg/m³ increment in mean ozone levels 2-3 day prior to symptom onset was associated with a 3.0% change in stroke risk (95% confidence interval: -1.2%, 7.3%). This association was statistically significantly enhanced by male gender, rural residence and low vegetable and fruit consumption. The subgroup results suggested that a fraction of the population might be considerably affected by ozone, regardless of the insignificant association in average level. The analysis of susceptibility distribution further indicated that the ozone-stroke association was statistically significantly positive in 14% of the general population. Susceptibility to ozone-related stroke significantly varied among Chinese adults. Characterizing individual-level susceptibility reveals the complexity underlying the weak average effect of ozone, and supports to plan subpopulation-specific interventions to mitigate the stroke risk.

Interactive effects of changing stratospheric ozone and climate on tropospheric composition and air quality, and the consequences for human and ecosystem health

The composition of the air we breathe is determined by emissions, weather, and photochemical transformations induced by solar UV radiation. Photochemical reactions of many emitted chemical compounds can generate important (secondary) pollutants including ground-level ozone (O₃) and some particulate matter, known to be detrimental to human health and ecosystems. Poor air quality is the major environmental cause of premature deaths globally, and even a small decrease in air quality can translate into a large increase in the number of deaths. In many regions of the globe, changes in emissions of pollutants have caused significant changes in air quality. Short-term variability in the weather as well as long-term climatic trends can affect ground-level pollution through several mechanisms. These include large-scale changes in the transport of O₃ from the stratosphere to the troposphere, winds, clouds, and patterns of precipitation. Long-term trends in UV radiation, particularly related to the depletion and recovery of stratospheric ozone, are also expected to result in changes in air quality as well as the self-cleaning capacity of the global atmosphere. The increased use of substitutes for ozone-depleting substances, in response to the Montreal Protocol, does not currently pose a significant risk to the environment. This includes both the direct emissions of substitutes during use and their atmospheric degradation products (e.g. trifluoroacetic acid, TFA).

Association between ambient air pollution and daily hospital admissions for ischemic stroke: A nationwide time-series analysis

BACKGROUND

Evidence of the short-term effects of ambient air pollution on the risk of ischemic stroke in low- and middle-income countries is limited and inconsistent. We aimed to examine the associations between air pollution and daily hospital admissions for ischemic stroke in China.

METHODS AND FINDINGS

We identified hospital admissions for ischemic stroke in 2014-2016 from the national database covering up to 0.28 billion people who received Urban Employee Basic Medical Insurance (UEBMI) in China. We examined the associations between air pollution and daily ischemic stroke admission using a two-stage method. Poisson time-series regression models were firstly fitted to estimate the effects of air pollution in each city. Random-effects meta-analyses were then conducted to combine the estimates. Meta-regression models were applied to explore potential effect modifiers. More than 2 million hospital admissions for ischemic stroke were identified in 172 cities in China. In single-pollutant models, increases of 10 μg/m3 in particulate matter with aerodynamic diameter <2.5 μm (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) and 1 mg/m3 in carbon monoxide (CO) concentrations were associated with 0.34% (95% confidence interval [CI], 0.20%-0.48%), 1.37% (1.05%-1.70%), 1.82% (1.45%-2.19%), 0.01% (-0.14%-0.16%), and 3.24% (2.05%-4.43%) increases in hospital admissions for ischemic stroke on the same day, respectively. SO2 and NO2 associations remained significant in two-pollutant models, but not PM2.5 and CO associations. The effect estimates were greater in cities with lower air pollutant levels and higher air temperatures, as well as in elderly subgroups. The main limitation of the present study was the unavailability of data on individual exposure to ambient air pollution.

CONCLUSIONS

As the first national study in China to systematically examine the associations between short-term exposure to ambient air pollution and ischemic stroke, our findings indicate that transient increase in air pollution levels may increase the risk of ischemic stroke, which may have significant public health implications for the reduction of ischemic stroke burden in China.

Acute effects of air pollution on ischaemic stroke onset and deaths: a time-series study in Changzhou, China

OBJECTIVE

To investigate the acute effect of air pollutants on ischaemic stroke (IS) and IS-related death.

SETTING

Five urban districts in Changzhou, China, between 9 January 2015 and 31 December 2016.

PARTICIPANTS

A total of 32 840 IS cases and 4028 IS deaths were enrolled.

MAIN OUTCOME MEASURES

A time-series design, generalised additive model and multivariable regression model were used to examine the percentage change (95% CI) in daily IS counts and deaths with an IQR increase in air pollutant levels for different single or multiple lag days in single-pollutant and two-pollutant models.

RESULTS

Daily IS counts increased 0.208% (95% CI 0.036% to 0.381%) with an IQR increment in the levels of nitrogen dioxide (NO2). The estimated risk of NO2 was more robust in males and in the cold season. For daily IS counts, the estimated effects of NO2 and sulfur dioxide (SO2) were more significant when adjusted for particulate matter with aerodynamic diameters <2.5 µm (PM2.5) and PM10. An IQR increment in the concentration of PM10, SO2 and NO2 significantly increased IS deaths with 6 days of cumulative effects (0.268%, 95% CI 0.007% to 1.528%; 0.34%, 0.088% to 0.592%; and 0.263%, 0.004% to 0.522%, respectively). Young individuals (<65 years old) had a higher IS mortality risk for PM2.5, PM10, NO2 and CO. For IS death, the effect estimates of SO2 in the elderly, females and the cold season were more pronounced; statistical significance was also identified for SO2 when adjusted for carbon monoxide (CO).

CONCLUSIONS

This study suggested that short-term exposure to ambient NO2 was associated with increased IS risk. In addition, SO2 was associated with increased IS onset and death.