Association between ambient air pollution and cardiovascular disease mortality: An individual-level case-crossover study in Hefei, China.

Background: Short-term exposure to air pollution is strongly associated to cardiovascular disease (CVD) mortality; however, detailed studies in rapidly urbanizing areas remain limited. This study aimed to examine short-term associations between ambient air pollutants and CVD mortality using individual-level data in Hefei City.

Methods: We conducted a case-crossover analysis involving 75,230 CVD deaths from 2017 to 2020 in Hefei, China. Individual exposure to fine particulate matter (PM_2.5), inhalable particulate matter (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon monoxide (CO), and ozone (O₃) was assessed using high-resolution satellite data (1 km resolution). The peak-effect lag days for individual pollutants within a 0-3 day exposure window were identified through conditional logistic regression analysis.

Results: Each 10 µg/m³ increase in SO₂ (lag 0-2) was associated with a 10.93 % (95 % CI: 6.65 %, 15.39 %) increase in CVD mortality, the strongest effect observed. PM_2.5 (lag 0) and NO₂ (lag 0-1) were associated with increases of 1.25 % (95 % CI: 0.82 %, 1.68 %) and 2.14 % (95 % CI: 1.38 %, 2.89 %), respectively. For CO (lag 0), each 0.1 mg/m³ increase was linked to a 1.22 % (95 % CI: 0.80 %, 1.64 %) increase in mortality. Other pollutants, including PM₁₀ and O₃, also showed weaker but statistically significant associations. Subgroup analyses revealed greater susceptibility among females and during the warm seasons compared to males and cold seasons.

Conclusions: Short-term exposure to ambient air pollutants significantly increases CVD mortality risk in Hefei, particularly among females and during warm seasons. These findings underscore the need for targeted public health interventions to mitigate pollution-related cardiovascular risks.