Joint Associations of Short-Term Exposure to Ambient Air Pollutants with Hospital Admission of Ischemic Stroke

The Associations of Short-Term Ambient Nitrogen Dioxide Pollution with Major Cause-Specific Morbidities and the Modifying Effects by Ambient Temperature: A Nationwide Case-Crossover Study

Consistent evidence linking short-term ambient nitrogen dioxide (NO2) exposure to cause-specific morbidities is limited to asthma, and the modifying effect by ambient temperature is unclear in the context of climate change. This two-stage time-stratified case-crossover study investigated the morbidity risks and burden of short-term NO2 exposure on major cause-specific hospital admissions (HAs) for respiratory diseases (RDs), cardiovascular diseases (CVDs), and kidney diseases in 291 Chinese cities of prefecture-level or above during 2013-2017, based on 47,182,205 HA records. For each 10 μg/m3 increase in NO2 at lag01, the overall percent changes in HAs ranged from 1.15% for asthma to 3.28% for chronic renal failure. Compared to NO2 concentrations <25 μg/m3, excess risks in HAs associated with exposure to NO2 concentrations ≥25 μg/m3 at lag01 ranged from 2.14% (acute coronary syndrome, ACS) to 4.56% (acute bronchitis). Total attributable fractions associated with short-term NO2 exposure ranged from 2.01% for ACS to 4.82% for chronic renal failure. Associations of NO2 with major cause-specific HAs were generally stronger at a low temperature than at a high temperature. These findings suggest that more stringent NO2 quality guidelines and regulations are needed in the context of climate change to generate additional health benefits.

The association between long-term exposure to PM2.5 constituents and ischemic stroke in the New York City metropolitan area

Numerous studies linked fine particulate matter (PM2.5) to ischemic stroke. However, only a few investigated the differential associations with specific PM2.5 components and sources. We utilized electronic health records (EHR) from the Mount Sinai Health System in the New York City metropolitan area during 2011-2019 and assessed the associations of PM2.5 components and sources with ischemic stroke. We used mixed-effect Poisson survival regressions to assess the single-exposure associations with the chemical components. We used multivariable regression to assess the simultaneous associations with source-apportioned PM2.5 exposures estimated using non-negative matrix factorization. Then, we assessed the sensitivity of our results to different specifications of EHR data continuity: (1) using a less strict definition of censorship year, (2) adjusting the model for EHR data continuity index, a validated algorithm measuring EHR-data continuity based on indicators of primary care service utilization. We observed higher risks for ischemic stroke (Risk ratio [95 % confidence intervals] per interquartile range increase) associated with higher exposure to nickel (1.080 [1.045; 1.116]), vanadium (1.070 [1.033; 1.109]), zinc (1.076 [1.031; 1.122]), and nitrate (1.084 [1.039; 1.132]). In the multivariate models we found higher risk for ischemic stroke associated with exposure to oil combustion sourced PM2.5 (1.061 [1.012; 1.113]). The results remained consistent under different model specifications accounting for EHR data continuity. In conclusion, we found an increased risk of ischemic stroke associated with specific PM2.5 components and sources. These findings were robust to different specifications of EHR-data continuity. Our findings can inform policy and interventions aimed at reducing cardiovascular disease burden.

Summer heatwave, ozone pollution and ischemic stroke mortality: An individual-level case-crossover study

BACKGROUND

Although the association of short-term ozone and heatwave exposure with cerebrovascular disease has been well documented, it remains largely unknown whether their co-exposure could synergistically trigger ischemic stroke (IS) mortality.

METHODS

We performed an individual-level, time-stratified case-crossover analysis utilizing province-wide IS deaths (n = 59079) in warm seasons (May-September) during 2016-2019, across Jiangsu, eastern China. Heatwave was defined according to a combination of multiple temperature thresholds (90-97.5th percentiles) and durations (2-4 days). Daily estimates of ozone concentration (0.01° × 0.01°) and heatwave (0.1° × 0.1°) were extracted from spatiotemporal grid dataset at subject's residential address. Conditional logistic regression models were utilized to evaluate the associations of short-term ozone and heatwave exposure with IS mortality. Multiplicative and additive interaction effects of ozone and heatwave were assessed using stratified analyses via dividing cases into low and high exposure groups.

RESULTS

Ozone exposure was associated with an increased odds of IS mortality, exhibiting an approximately linear trend across the broad concentration range of 59-227 μg/m3. Under various heatwave definitions, the odds of IS mortality associated with heatwave ranged from 1.167 (95% confidential interval [CI]: 1.135, 1.199) to 1.497 (95% CI: 1.431, 1.565) in the total population. Stratified analyses suggested intensified ozone-related IS risk on heatwave days than non-heatwave days, and intensified heatwave-related risk on high-ozone days than low-ozone days. We observed significant synergistic effects of heatwave and ozone on IS mortality, with relative excess odds due to interaction ranging from 0.15 (95% CI: 0.08, 0.22) to 0.26 (95% CI: 0.13, 0.39). For heatwave with stricter definition, the heatwave and joint ozone-heatwave effects on IS mortality tended to become stronger. We estimated that 3.66% (95% CI: 1.87%, 5.39%) to 4.19% (95% CI: 2.57%, 5.76%) of IS deaths could be attributable to heatwave and ozone exposure. The elderly aged 85+ years were at higher vulnerability to heatwave and co-exposure event of extreme heat and ozone pollution.

CONCLUSIONS

Compound ozone and heatwave exposure may synergistically trigger IS deaths, and old adults were at higher vulnerability to exposure-related excess risk. Coordinated governance of climate change and air pollution may potentially bring substantial cerebrovascular health benefit.

Effect of Ozone Exposure on Cardiovascular and Cerebrovascular Disease Mortality in the Elderly

BACKGROUND

Ozone pollution has increased alongside China's economic development, contributing to public health issues such as cardiovascular and cerebrovascular diseases. At present, the problem of an aging population is aggravated, which is worth more attention in terms of the health problems of elderly people.

METHODS

This study employed a distributional lag nonlinear model (DLNM) with Poisson regression to analyze the impact of ozone on cardiovascular and cerebrovascular disease mortality among the elderly in Shenyang, China, from 2014 to 2018. In addition, a time-series generalized additive regression model (GAM) was used to analyze the joint effect between PM2.5 and ozone.

RESULTS

We found a positive correlation between ozone and mortality from cardiovascular and cerebrovascular diseases in the elderly. The maximum relative risk (RR) of mortality from cardiovascular and cerebrovascular diseases for every 10 μg/m3 increase in ozone was 1.005 (95% CI: 1.002-1.008). Males (RR: 1.018, 95% CI: 1.007-1.030), individuals in unconventional marital status (RR: 1.024, 95% CI: 1.011-1.038), and outdoor workers (RR: 1.017, 95% CI: 1.002-1.031) were more vulnerable to ozone pollution. This study did not find significant differences in the impact of ozone pollution on cardiovascular and cerebrovascular disease mortality risks among different educational groups. Additionally, a joint effect between ozone and PM2.5 was observed.

CONCLUSION

This study confirms that ozone exposure is positively associated with increased mortality from cardiovascular and cerebrovascular diseases. It emphasizes the joint effect of ozone and PM2.5 in exacerbating cardiovascular and cerebrovascular disease mortality.

Causal effects of key air pollutants and meteorology on ischemic stroke onset: A convergent cross-mapping approach

BACKGROUND

Evidence suggests that environmental factors may influence the risk of ischemic stroke(IS).1 Nevertheless, the majority of existing research has concentrated on correlation analysis, with only a limited number of studies employing specific methodologies to investigate the causal dynamics of this relationship with external drivers.

METHOD

In this study, we employed an approach known as convergent cross-mapping to identify and elucidate the causal effects of significant air pollutants and meteorological factors on the pathogenesis of IS. The city of Shouguang in the Shandong Peninsula region was selected for this study, primarily because of the environmental characteristics of the region and the notable prevalence of cases during the study period.

RESULTS

Key air pollutants and several meteorological factors in the region have a causal effects on IS. A general trend can be drawn. SO22 (ρ = 0.215, ∂=0.016), PM2.53 (ρ = 0.077, ∂=0.002), and PM104 (ρ = 0.058, ∂=0.0014) had a positive causal effects on IS,and relative humidity (ρ = 0.050, ∂=-0.009) tended to reduce the number of IS cases.

CONCLUSION

Through this case study, a causal network was developed with the aim of integrating the study of the interactions between variables and providing a clear model to aid the management of IS.

Current trend in air pollution exposure and stroke

PURPOSE OF REVIEW

Stroke is the second leading cause of death worldwide, and exposure to particulate air pollution is now recognized as one of the major modifiable risk factors. However, air pollution can vary in terms of physicochemical composition and exposition specificities. Therefore, its relationships with stroke outcomes remain under intense investigation.

RECENT FINDINGS

This review highlights, alongside particles, that short-term and long-term exposure to nitrogen dioxide (NO 2 ) and ozone is likely to be also linked to stroke-related morbidity and mortality. Moreover, air pollution may increase the risk of transitioning from a healthy status to incident stroke and morbimortality after stroke. Additionally, relationships may vary depending on the air pollution mixture (e.g., particle-related components, pollutant interactions), pollutant sources (e.g., traffic-related or not), stroke etiology (ischemic or hemorrhagic), or exposed individual's characteristics (e.g., age, sex, genetic predisposition, weight status). Nonlinear dose-response functions and short-term effect lags have been reported, but these features need further refinement.

SUMMARY

The relationship between stroke and air pollution is now well established. Nonetheless, future research should further consider the physicochemical properties of air pollutants, multiple exposures, and individual vulnerabilities. Moreover, advanced statistical methods should be more commonly used to better describe the relationship shapes.

Association of PM2.5 exposure in early pregnancy and maternal liver function: A retrospective cohort study in Shenzhen, China

OBJECTIVE

Studies have shown that fine particulate matter (PM2.5) has adverse effects on the liver function, but epidemiological evidence is limited, especially regarding pregnant women. This study aims to investigate the association between PM2.5 exposure in early pregnancy and maternal liver function during pregnancy.

METHODS

This retrospective cohort study included 13,342 pregnant participants. PM2.5 and Ozone (O3) exposure level, mean temperature, and relative humidity for each participant were assessed according to their residential address. The levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TBIL) were measured during the second and third trimesters. Data on PM2.5 and O3 exposure level were sourced from Tracking Air Pollution in China (TAP), while the mean temperature and relative humidity were obtained from the ERA5 dataset. The Generalized Additive Model (GAM) was used to analyze the associations between PM2.5 exposure and maternal liver function during pregnancy, adjusting for potential confounding factors.

RESULTS

According to the results, each 10 μg/m3 increase in PM2.5 was associated with an increase of 3.57% (95% CI: 0.29%, 6.96%) in ALT and 4.25% (95% CI: 2.33%, 6.21%) in TBIL during the second trimester and 4.51% (95% CI: 2.59%, 6.47%) in TBIL during the third trimester, respectively. After adjusting for O3, these associations remained significant, and the effect of PM2.5 on ALT during the second trimester was further strengthened. No significant association observed between PM2.5 and AST.

CONCLUSIONS

PM2.5 exposure in early pregnancy is associated with increasement of maternal ALT and TBIL, suggesting that PM2.5 exposure may have an adverse effect on maternal liver function. Although this finding indicates an association between PM2.5 exposure and maternal liver function, more research is needed to confirm our findings and explore the underlying biological mechanisms.

Time-Series analysis of short-term exposure to air pollutants and daily hospital admissions for stroke in Tabriz, Iran

BACKGROUND

Air pollution is considered one of the risk factors for stroke prevalence in the long term and incidence in the short term. Tabriz is one of the most important industrial cities in Iran. Hence, air pollution has always been one of the main concerns in environmental health in the region.

METHOD

The patient data were retrieved from electronic health records of the primary tertiary hospital of the city (Imam Reza Hospital). Air pollution data was obtained from the Environmental Protection Agency and is generated by 8 sensor stations spread across the city. Average daily values were calculated for CO, NO, NO, NOx, O3, SO2, PM2.5, and PM10 from hourly measurement data. Autoregressive integrated moving average (ARIMA-X) model with 3 lag days was developed to assess the correlation.

RESULTS

Air pollutants and hospital admission data were collected for 1821 day and includes 4865 stroke cases. our analysis showed no statistically significant association between the daily concentrations of CO (p = 0.41), NOx (p = 0.96), O3 (p = 0.65), SO2 (p = 0.91), PM2.5 (p = 0.44), and PM10 (p = 0.36). Only the binary COVID variable which was used to distinguish between COVID-19 era and other days, was significant (p value = 0.042). The goodness of fit measures, Root Mean Squared Error (RMSE), and Median Absolute Error (MAE) were 1.81 and 1.19, respectively.

CONCLUSION

In contrast to previous reports on the subject, we did not find any pollutant significantly associated with an increased number of stroke patients.

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.

The joint effects of mixture exposure to multiple meteorological factors on step count: A panel study in China

The public health burden of increasing extreme weather events has been well documented. However, the influence of meteorological factors on physical activity remains limited. Existing mixture effect methods cannot handle cumulative lag effects. Therefore, we developed quantile g-computation Distributed lag non-linear model (QG-DLNM) by embedding a DLNM into quantile g-computation to allow for the concurrent consideration of both cumulated lag effects and mixture effects. We gathered repeated measurement data from Henan Province in China to investigate both the individual impact of meteorological factor on step counts using a DLNM, and the joint effect using the QG-DLNM. We projected future step counts linked to changes in temperature and relative humidity driven by climate change under three scenarios from the sixth phase of the Coupled Model Intercomparison Project. Our findings indicate there are inversed U-shaped associations for temperature, wind speed, and mixture exposure with step counts, peaking at 11.6 °C in temperature, 2.7 m/s in wind speed, and 30th percentile in mixture exposure. However, there are negative associations between relative humidity and rainfall with step counts. Additionally, relative humidity possesses the highest weights in the joint effect (49% contribution). Compared to 2022s, future step counts are projected to decrease due to temperature changes, while increase due to relative humidity changes. However, when considering both future temperature and humidity changes driven by climate change, the projections indicate a decrease in step counts. Our findings may suggest Chinese physical activity will be negatively influenced by global warming.

The joint associations of ambient air pollutants and weather factors with mortality: Evidence from a national time-stratified case-crossover study in China

BACKGROUND

People in daily life are usually exposed to multiple environmental factors, but few studies have evaluated the joint health impacts of ambient air pollutants and weather factors.

OBJECTIVES

To investigate the joint associations of short-term exposures to ambient air pollutants and weather factors with mortality and estimate the mortality burden attributable to these multiple environmental exposures in China.

METHODS

We collected individual death information from six provinces (Guangdong, Yunnan, Hunan, Zhejiang, Tibet and Jilin) in China during 2013 to 2018, and applied a time-stratified case-crossover study design to estimate the joint associations of air pollutants [PM2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm), O3 (ozone), NO2 (nitrogen dioxide), SO2 (sulfur dioxide), and CO (carbon monoxide)] and weather factors (temperature and relative humidity) with mortality. Air pollutant concentrations on the case day and control days were assessed using a random forest model, and the corresponding temperature and relative humidity data were assessed using a thin plate smoothing model. Excess risks (ER) of exposure to air pollutants and weather factors were estimated using Cox proportional regression models and the attributable fraction (AF) was calculated.

RESULTS

A total of 6,685,146 deaths were enrolled in this study. The overall AF of total mortality attributed to air pollutants (lag03 days) and weather factors (lag021 days) was 16.65 % (95%CI: 16.43 %, 16.87 %), in which the joint AFs attributable to air pollutants and weather factors were 5.31 % (95%CI: 5.08 %, 5.53 %) and 11.34 % (95%CI: 11.12 %, 11.56 %) respectively, and temperature contributed 56 % in the joint effects. Stratified analyses showed greater AFs in females (21.32 %) than in males (14.61 %), and in the elderly (>100 years, 42.34 %) than in young people (21-30 years, 7.67 %). The AFs of mortality from cardiovascular diseases, respiratory diseases, and pneumonia attributed to the joint exposures were 22.72 %, 24.82 % and 33.03 %, respectively.

DISCUSSION

This study provides the joint associations of short-term exposures to both air pollutants and weather factors with mortality risk in China, which has important implications in comprehensively assessing the health impacts of environmental exposures, and taking actions to protect human health.

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.

Joint Effects of Long-Term Exposure to Ambient Fine Particulate Matter and Ozone on Asthmatic Symptoms: Prospective Cohort Study

BACKGROUND

The associations of long-term exposure to air pollutants in the presence of asthmatic symptoms remain inconclusive and the joint effects of air pollutants as a mixture are unclear.

OBJECTIVE

We aimed to investigate the individual and joint associations of long-term exposure to ambient fine particulate matter (PM2.5) and daily 8-hour maximum ozone concentrations (MDA8 O3) in the presence of asthmatic symptoms in Chinese adults.

METHODS

Data were derived from the World Health Organization Study on Global Ageing and Adult Health (WHO SAGE) cohort study among adults aged 50 years or older, which was implemented in 1 municipality and 7 provinces across China during 2007-2018. Annual average MDA8 O3 and PM2.5 at individual residential addresses were estimated by an iterative random forest model and a satellite-based spatiotemporal model, respectively. Participants who were diagnosed with asthma by a doctor or taking asthma-related therapies or experiencing related conditions within the past 12 months were recorded as having asthmatic symptoms. The individual associations of PM2.5 and MDA8 O3 with asthmatic symptoms were estimated by a Cox proportional hazards regression model, and the joint association was estimated by a quantile g-computation model. A series of subgroup analyses was applied to examine the potential modifications of some characteristics. We also calculated the population-attributable fraction (PAF) of asthmatic symptoms attributed to PM2.5 and MDA8 O3.

RESULTS

A total of 8490 adults older than 50 years were included, and the average follow-up duration was 6.9 years. During the follow-up periods, 586 (6.9%) participants reported asthmatic symptoms. Individual effect analyses showed that the risk of asthmatic symptoms was positively associated with MDA8 O3 (hazard ratio [HR] 1.12, 95% CI 1.01-1.24, for per quantile) and PM2.5 (HR 1.18, 95% CI 1.05-1.31, for per quantile). Joint effect analyses showed that per equal quantile increment of MDA8 O3 and PM2.5 was associated with an 18% (HR 1.18, 95% CI 1.05-1.33) increase in the risk of asthmatic symptoms, and PM2.5 contributed more (68%) in the joint effects. The individual PAFs of asthmatic symptoms attributable to PM2.5 and MDA8 O3 were 2.86% (95% CI 0.17%-5.50%) and 4.83% (95% CI 1.42%-7.25%), respectively, while the joint PAF of asthmatic symptoms attributable to exposure mixture was 4.32% (95% CI 1.10%-7.46%). The joint associations were greater in participants with obesity, in urban areas, with lower family income, and who used unclean household cooking fuel.

CONCLUSIONS

Long-term exposure to PM2.5 and MDA8 O3 may individually and jointly increase the risk of asthmatic symptoms, and the joint effects were smaller than the sum of individual effects. These findings informed the importance of joint associations of long-term exposure to air pollutants with asthma.