Coarse Particulate Air Pollution and Daily Mortality A Global Study in 205 Cities

Rationale: The associations between ambient coarse particulate matter (PM_2.5–10) and daily mortality are not fully understood on a global scale. Objectives: To evaluate the short-term associations between PM_2.5–10 and total, cardiovascular, and respiratory mortality across multiple countries/regions worldwide. Methods: We collected daily mortality (total, cardiovascular, and respiratory) and air pollution data from 205 cities in 20 countries/regions. Concentrations of PM_2.5–10 were computed as the difference between inhalable and fine PM. A two-stage time-series analytic approach was applied, with overdispersed generalized linear models and multilevel meta-analysis. We fitted two-pollutant models to test the independent effect of PM_2.5–10 from copollutants (fine PM, nitrogen dioxide, sulfur dioxide, ozone, and carbon monoxide). Exposure–response relationship curves were pooled, and regional analyses were conducted. Measurements and Main Results: A 10 μg/m³ increase in PM_2.5–10 concentration on lag 0–1 day was associated with increments of 0.51% (95% confidence interval [CI], 0.18%–0.84%), 0.43% (95% CI, 0.15%–0.71%), and 0.41% (95% CI, 0.06%–0.77%) in total, cardiovascular, and respiratory mortality, respectively. The associations varied by country and region. These associations were robust to adjustment by all copollutants in two-pollutant models, especially for PM_2.5. The exposure–response curves for total, cardiovascular, and respiratory mortality were positive, with steeper slopes at lower exposure ranges and without discernible thresholds. Conclusions: This study provides novel global evidence on the robust and independent associations between short-term exposure to ambient PM_2.5–10 and total, cardiovascular, and respiratory mortality, suggesting the need to establish a unique guideline or regulatory limit for daily concentrations of PM_2.5–10