Background: Air pollution is a major public health concern associated with increased respiratory and cardiovascular mortality. This study investigates the effects of air pollution and meteorological factors on respiratory, cardiovascular, and all-cause mortality in Mashhad, Iran, using generalized additive models with cumulative lag structures.
Methods: Daily mortality data from February 18, 2017, to March 19, 2020, were classified by cause. Air pollutants (PM10, PM2.5, NO2, SO2, and CO) and meteorological data (temperature and humidity) were analyzed using quasi-Poisson GAMs, adjusting for temporal trends, weather, and day of the week. Lag effects (0–10, 0–20, and 0–30 days) were assessed for pollutant impacts on mortality.
Results: Higher PM2.5, PM10, and NO2 levels were significantly associated with increased risks of all-cause, respiratory, and cardiovascular mortality. A 10-unit increase in PM2.5 was associated with the highest risk for all-cause mortality at Lag 0–30 (RR = 1.184, P = 0.012). PM2.5 and NO2 showed the strongest associations with respiratory mortality over 30-day cumulative exposure, while PM2.5 (RR = 1.132, 95% CI: 1.012–1.267) and NO2 (RR = 1.074, 95% CI: 1.006–1.147) also impacted cardiovascular deaths. Shorter lags revealed more immediate impacts, particularly for NO2 and PM2.5 on all-cause mortality.
Conclusion: These findings underscore the urgent need for strategies to reduce air pollution in Mashhad, addressing both short- and long-term health effects, particularly respiratory and cardiovascular outcomes. The results support policy interventions for improved air quality management in urban Iran.