Background: Inconsistent results have been found on the association between air pollution and stroke mortality. Additionally, evidence on people who are potentially sensitive to air pollution-associated stroke mortality is limited. Methods: Daily stroke mortality of adults aged over 65 between 2003 and 2008 in Shanghai, China were collected. The time-stratified case-crossover approach was used to assess the association between daily concentrations of air pollutants including particles with size <10 µm, sulfur dioxide (SO₂) and nitrogen dioxide (NO₂) and stroke mortality. Results: Both total-stroke and ischaemic-stroke mortalities were found to be significantly associated with all three air pollutants. Haemorrhagic stroke was significantly associated with SO₂ and NO₂ only. Substantial differences were observed for effect estimates of ischaemic-stroke mortality in relation to NO₂ among people with cardiac diseases compared with those without; for an increase of 10 μg/m³ in NO₂, the increase in ischaemic-stroke mortality was 7.05% (95% CI 1.92% to 12.17%) for people with comorbid cardiac diseases versus 0.60% (95% CI −0.49% to 1.68%) for those without. We did not find evidence of effect modification by hypertension and diabetes. Conclusions: This study provides new evidence for the association between exposure to ambient air pollution and stroke mortality. Our results also suggest that underlying cardiac disorder may increase the risk for ischaemic-stroke mortality in relation to air pollution exposure, especially NO₂. .

Few studies investigating associations between fine particulate air pollution and hemorrhagic stroke have considered subtypes. Additionally, less is known about the modification of such association by factors measured at the individual level. We aimed to investigate the risk of fatal intracerebral hemorrhage (ICH) incidence in case of PM2.5 (particles ≤ 2.5 μm in aerodynamic diameter) exposure. Data on incidence of fatal ICH from 1 June 2012 to 31 May 2014 were extracted from the acute stroke mortality database in Shanghai Municipal Center for Disease Control and Prevention (SCDC). We used the time-stratified case-crossover approach to assess the association between daily concentrations of PM2.5 and fatal ICH incidence in Shanghai, China. A total of 5286 fatal ICH cases occurred during our study period. The averaged concentration of PM2.5 was 77.45 μg/m3. The incidence of fatal ICH was significantly associated with PM2.5 concentration. Substantial differences were observed among subjects with diabetes compared with those without; following the increase of PM2.5 in lag2, the OR (95% CI) for subjects with diabetes was 1.26 (1.09–1.46) versus 1.05 (0.98–1.12) for those without. We did not find evidence of effect modification by hypertension and cigarette smoking. Fatal ICH incidence was associated with PM2.5 exposure. Our results also suggested that diabetes may increase the risk for ICH incidence in relation to PM2.5.

Objectives: Evidence of the association between fine particulate (PM_2.5, particles ≤2.5 μm in aerodynamic diameter) air pollution and fatal hemorrhagic stroke incidence is limited. This study aims to document the relationship between PM_2.5 exposure and fatal hemorrhagic stroke incidence. Methods: The time-stratified case-crossover approach was applied for the analysis. Results: The mean concentration of PM_2.5 is 75.33 μg/m³. Fatal hemorrhagic stroke incidence was significantly associated with PM_2.5 exposure. Exposure to PM_2.5 led to a 5% (2%–9%) and 5% (1%–10%) increase in fatal hemorrhagic stroke incidence in lag2 and lag03 respectively. An increased risk was observed especially in men and subjects with hypertension. Conclusions: This study provides evidence for the association between PM_2.5 exposure and fatal hemorrhagic stroke incidence. Men and subjects with hypertension have increased risks, overweight may further increase their susceptibility to PM_2.5 exposure related hemorrhagic stroke.