Hourly Air Pollution Exposure and Emergency Hospital Admissions for Stroke: A Multicenter Case-Crossover Study

Air pollution and stroke: Short-term exposure's varying effects on stroke subtypes

BACKGROUND

Few studies have examined how air pollutants affect various stroke subtypes and how these effects differ with stroke severity, especially among European populations living in less polluted areas.

METHODS

We conducted a time-stratified case-crossover study using 15 years of hospital-based stroke data from the University Hospital Augsburg in Southern Germany. Daily average air pollutants, including particulate matter (PM) with an aerodynamic diameter < 10μm (PM10), coarse particles (PMcoarse), fine particles (PM2.5), ozone (O3), nitrogen oxides (NO2, NO), and meteorological data were obtained from local fixed urban background monitoring sites from 2006 to 2020. Conditional logistic regression was utilized to estimate the relationship between pollutants and daily stroke events, with modification effects being examined through stratified and interaction analyses.

RESULTS

Based on 19,518 included stroke cases, each interquartile range (IQR) increase in PM2.5, PM10, PMcoarse, and NO2 was associated with a 2.11 %, 2.55 %, 2.50 %, and 3.48 % rise in overall stroke events 5-6 days later. Positive associations were seen mostly for transient ischemic attacks and hemorrhagic strokes. Notably, people with severe stroke-induced disabilities were disproportionately affected by PM and NO2, while those with mild disabilities were more affected by O3 and NO. Moreover, damaging effects were amplified during warm seasons and the 2016-2020 five-year period.

CONCLUSION

Short-term air pollution exposure may trigger stroke events, with differential impacts depending on stroke subtype and severity of pre-existing disability. A coordinated effort is needed for stroke prevention in response to specific air pollutants, especially in the context of global warming.

Association between particulate matter exposure and acute ischemic stroke admissions in less-polluted areas: a time-series study using a distributed lag nonlinear model

Purpose

China has experienced a heavy public health burden due to the increasing incidence of ischemic stroke (IS). Few studies have evaluated the relationship between particulate matter (PM) exposure and acute ischemic stroke (AIS) in relatively less-polluted areas, and the results have been inconsistent. As a result, this study aimed to investigate and evaluate the association between PM exposure and hospitalizations for AIS in an area with less air pollution.

Methods

Through collecting daily AIS hospitalizations, air pollution data and meteorological data from July 1, 2017 to June 30, 2020 in Nanning, this paper explored the association between short-term exposure to PM (PM2.5, PM10 and PMc) and daily hospital admissions for AIS using a distributed lag non-linear model based on time-series. To further identify the susceptible populations, stratified analyses were performed by age and gender.

Results

During the study period, a total of 2382 patients were admitted to hospital with AIS, with the ratio of male to female reached 2.03: 1. No statistical association was found between PM exposure and AIS admissions in the total population. Subgroup analysis showed that PM2.5, PM10 and PMc exposures were significantly associated with AIS admissions in male at lag29-lag30, lag27-lag30 and lag25-lag27, respectively. In addition, PMc exposure was also relevant to admissions for AIS with aged < 65 years at lag18-lag23.

Conclusions

Short-term exposure to ambient PM was not associated with hospital admissions for AIS in the general population, but males and young adults (aged < 65 years) were more susceptible to PM exposure. Even in areas with relatively low air pollution, appropriate measures should be adopted to intervene in the adverse effects of air pollution on vulnerable populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-024-00926-w.

Joint effect of modifiable risk factors and genetic susceptibility on ischaemic stroke

PURPOSE

To investigate the effects of modifiable risk factors and genetic susceptibility on ischaemic stroke (IS).

METHODS

A total of 490365 participants from the UK Biobank, with a 17-year follow-up, were included in this study. Data on 115 modifiable exposures were collected from five domains: early life, environment, lifestyle, socioeconomic status, and physical measures. Additionaly, genetic data were collected. An exposure-wide association analysis was conducted to identify potential risk factors. Risk scores for each domain and genes were calculated. The effect of each domain score on IS and the joint effects among the five domains were analyzed using multi-variate Cox models. The population attributable fraction was estimated to quantize the impact of eliminating unfavorable factors.

RESULTS

Sixty-four of the 115 modifiable exposures were found to be significantly associated with the risk of IS (P < 4.35 × 10-4 for Bonferroni correction). Newly identified factors included maternal smoking and being either overweight or underweight at age 10, which could significantly increase the risk of IS by 4.78 % to 14.74 %, 11.01 % to 23.75 %, and 3.29 % to 12.80 %, respectively. Additionally, exposure to hard water was associated with a decreased risk of IS by 6.96 % to 11.48 % compared to exposure to soft water. The associations varied across domains, with socioeconomic factors accounting for 5.2 % of IS cases, lifestyle accounting for 2.8 %, and physical measures accounting for 2.5 %, representing the top three contributing factors. Overall, it was estimated that 10.6 % to 11.3 % of IS cases could be prevented by eliminating the identified risks.

CONCLUSIONS

Interactions between risk factors and genetic susceptibility elevated the risk of IS. Risk factors from different domains contributed variably to IS, with socioeconomic factors accounting for the largest proportion.

Associations of long-term exposure to fine particle and its components with ischemic stroke: A cohort study in China

BACKGROUND

Several studies have demonstrated that prolonged exposure to PM2.5 is associated with elevated risks of developing ischemic stroke (IS). However, evidence on the association of PM2.5 components with IS is still lacking. Thus, we aimed to estimate the association of 15 chemical components of PM2.5 with risk of IS in a cohort study.

METHODS

A community-based prospective cohort study comprising 29,926 participants was conducted in Yinzhou district, Ningbo, China. We utilized a land-use regression model to calculate the concentrations of PM2.5 and its 15 components. Adaptive elastic net (AENET) models were used to select important components from 135 predictors and environmental risk score (ERS) was calculated to quantify the multi-pollutant combined effect. Cox proportional hazard models and restricted cubic splines were used to estimate the associations of PM2.5 components with the occurrence of IS.

RESULTS

During 156,694 person-years of follow-up period, 770 new IS cases were identified. In single pollutant model, every IQR increased in PM2.5 (HR=1.240, 95 % CI: 1.098-1.401) and mercury (HR=1.441, 95 % CI: 1.240-1.675) was positively associated with risk of IS, whereas every IQR increased in cadmium (HR=0.935, 95 % CI: 0.900-0.971), antimony (HR=0.867, 95 % CI: 0.761-0.987), selenium (HR=0.700, 95 % CI: 0.611-0.802), and ammonium (HR=0.797, 95 % CI: 0.709-0.897) were inversely associated with IS. ERS was constructed by AENET according to 3 main effects (lead, selenium, and thallium), 3 square terms (beryllium, cadmium, and selenium), and 2 component-component interactions (beryllium × mercury and cadmium × selenium). A higher ERS was associated with a higher risk of IS (every IQR increased: HR=1.429, 95 % CI: 1.275-1.601).

CONCLUSIONS

Long-term exposure to PM2.5 and its constituents may increase the risk of IS. Three heavy metals in PM2.5 from soil dust and coal combustion (lead, selenium, and cadmium), as well as three from non-ferrous metallurgy (thallium, beryllium, and mercury), contributed the most.

Interactive Effect of Air Temperature and Fine Particulate Matter on the Hospital Admissions for Stroke in Shenzhen, China

BACKGROUND

Stroke is a major health challenge in China. Numerous studies have linked stroke with temperature and fine particulate matter (PM2.5), but findings varied by stroke subtypes and regions, and few explored the interactive effects of air temperature and PM2.5. This study examines the association between air temperature, PM2.5, and stroke hospital admissions in Shenzhen, a subtropical monsoon city in southern China.

METHODS AND RESULTS

We applied time-series generalized additive models to estimate the individual and interactive effects of air temperature and PM2.5 on stroke hospital admissions using daily records from 2015 to 2016. Subgroup analysis by sex, age, and education level was conducted, assessing admissions for hemorrhagic (n=8752) and ischemic (n=33 233) stroke separately. For hemorrhagic stroke, a 1 °C increase in temperature was significantly associated with a 2.3% (95% CI, -3.2% to -1.3%) decrease in hospital admissions, whereas higher levels of PM2.5 indicated an increased risk, though not significant. Conversely, for ischemic stroke, a 1 °C rise was significantly associated with a 1.0% (95% CI, 0.4%-1.6%) increase in admissions. The impact PM2.5 on stroke was more pronounced at higher concentrations, while showing no evident effects at lower levels. Interaction effects between temperature and PM2.5 were statistically significant for both stroke types, with stronger effects observed at 10 to 20 °C and PM2.5 concentration around 80 to 100 μg/m3.

CONCLUSIONS

This study suggests lower air temperature may increase hemorrhagic stroke risk, whereas higher temperature and higher PM2.5 exposure may increase ischemic stroke risk. Interactive effects between temperature and PM2.5 were observed for both stroke types in Shenzhen.

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.

Effect of nitrogen oxides and sulfur oxides to triphenyl phosphate degradation and cytotoxicity on surface of different transition metal salts

Nitrogen oxides and sulfur oxides, as the dominant toxic gases in the atmosphere, can induce severe human health problems under the composite pollutant conditions. Currently the effect of nitrogen or sulfur oxides in atmospheric environment to the degradation and cytotoxicity of triphenyl phosphate (TPhP) on atmospheric particle surfaces still remain poorly understood. Hence, laboratory simulation methods were used in this study to investigate the effect and related mechanism. First, particle samples were prepared with the TPhP coated on MnSO4, CuSO4, FeSO4 and Fe2(SO4)3 surface. The results showed that, when nitrogen or sulfur oxides were present, more significant TPhP degradation on all samples can be observed under both light and dark conditions. The results proved nitrogen oxides and sulfur oxides were the vital influence factors to the degradation of TPhP, which mainly promoted the OH generation in the polluted atmosphere. The mechanism study indicated that diphenyl hydrogen phosphate (DPhP) and OH-DPhP were two main stable degradation products. These degradation products originated from the phenoxy bond cleavage and hydroxylation of TPhP caused by hydroxyl radicals. In addition, no TPhP related organosulfates (OSs) or organic nitrates (ON) formation were observed. Regarding the cytotoxicity, all the particles can induce more significant cellular injury and apoptosis of A549 cells, which may be relevant to the adsorbed nitrogen oxides or sulfur oxides on particles surfaces. The superfluous reactive oxygen species (ROS) generation was the possible reason of cytotoxicity. This research can supply a comprehensive understanding of the promoting effect of nitrogen and sulfur oxides to TPhP degradation and the composite cytotoxicity of atmospheric particles.

Hourly effect of atmospheric reactive nitrogen species on the onset of acute ischemic stroke: Insight from the Shanghai Stroke Service System Database

Acute ischemic stroke (AIS) is one of the most predominant causes of mortality and disability in China. Significant uncertainties in stroke diagnosis and time of onset have resulted in inconsistent evidence on the association between ambient air pollution and the risk of AIS. The present study aimed to evaluate the impact of air pollution on AIS onset based on high time-resolution air pollution data and a stroke-specific registry across the past five years. Hourly concentrations of PM2.5, PM10, O3, SO2, CO, NO2 and nitrous acid (HONO) were monitored from 2017 to 2021, with which a distributed lag non-linear model and conditional logistic regression models coupled with a time-stratified case-crossover design were applied to 106,623 AIS cases recorded in the Shanghai Stroke Service (4S) database during the study period. Results from the conditional logistic regression models indicate that acute exposure to PM2.5, PM10, SO2, NO2 and HONO was found to be associated with AIS onset, respectively. The corresponding cumulative excessive risks of AIS onset were 0.8 %, 1 %, 2.4 %, 2.1 % and 1.8 % for each interquartile range increase in the respective concentration. The longest lag-effect (up to 13 h) was observed for reactive nitrogen species (RNS), such as NO2 and HONO, which remained robust in two-pollutant models. Similar important role of RNS in AIS onset were confirmed by the distributed lag non-linear model. By demonstrating the transient effect of ambient air pollution on AIS, especially the relationships between RNS and AIS for the first time, our study provides stringent evidence for future mitigation strategies for pollution emission and public health.

Residential Nitrogen Dioxide Exposure and Cause-Specific Cerebrovascular Mortality: An Individual-Level, Case-Crossover Study

BACKGROUND

Existing studies have already shown a connection between nitrogen dioxide (NO2) exposure and cerebrovascular mortality. However, the differential effects of NO2 on cerebrovascular disease and its subtypes remain unclear and require further exploration.

METHODS

Daily stroke mortality data between 2013 and 2021 in Shanghai, China were collected. Residential daily air pollution data for each decedent were predicted from a satellite model. An individual-level, time-stratified, case-crossover design was applied to examine the relationship between NO2 exposure and cerebrovascular mortality. A combination of conditional logistic regression and distributed lag models with a maximum lag of 7 days was used for data analysis.

RESULTS

A total of 219,147 cases of cerebrovascular mortality were recorded. Among them, the proportion of sequelae of cerebrovascular disease, hemorrhagic stroke and ischemic stroke was 50.7%, 17.1% and 27.5%, respectively. The monotonic increases in mortality risks of cerebrovascular diseases, sequelae of cerebrovascular disease and ischemic stroke were observed, without any discernible thresholds. Each 10 μg/m3 increase in NO2 concentration was associated with increments of 3.62% [95% confidence interval (CI): 2.56%, 4.69%] for total cerebrovascular mortality, 4.29% (95% CI: 2.81%, 5.80%) for sequelae of cerebrovascular disease mortality and 4.30% (95% CI: 2.30%, 6.33%) for ischemic stroke mortality. No positive associations between NO2 exposure and hemorrhagic stroke mortality were observed. A greater risk of NO2 was observed in the warm season, in patients with less than 9 years of education and in those with single marital status. The effects of NO2 were robust to mutual adjustment of co-pollutants.

CONCLUSIONS

Short-term exposures to NO2 may increase the risk of cerebrovascular mortality, specifically for ischemic stroke and sequelae of cerebrovascular disease.