Fine particulate matter constituents and cause-specific mortality in China: A nationwide modelling study

Fine particulate matter (with aerodynamic diameter ≤2.5 µm, PM_2.5) causes huge disease burden worldwide. However, evidence is still inadequate and inconsistent on the relationships between PM_2.5 constituents and mortality, especially in low resource settings.

To evaluate the impact of PM_2.5 constituents on cause-specific mortality in China.

We obtained daily mortality data for 161 communities in 2011-2013 from the Disease Surveillance Point system in China. Daily concentrations of major PM_2.5 constituents, including organic carbon (OC), elemental carbon (EC), sulphate (SO₄^2-), nitrate (NO₃^-) and ammonium (NH₄⁺), were estimated by using the modified Community Multiscale Air Quality model. For each community, we applied quasi-Poisson regression and polynomial distributed lag models to estimate the effects of PM_2.5 constituents on cause-specific mortality. Then, the pooled effect estimates were calculated by a random-effect meta-analysis based on the restricted maximum likelihood estimation. Stratification analyses were performed by region, gender, age group and education level to identify the vulnerable populations.

Each interquartile range change of EC, OC, SO₄^2-, NO₃^- and NH₄⁺ at lag 0-3 day was associated with increments in non-accidental mortality of 0.45% (95%CI: 0.21, 0.69), 1.43% (0.97, 1.89), 0.71% (0.28, 1.15), 0.70% (0.10, 1.30) and 0.95% (0.39, 1.51), respectively. The associations were stronger for the deaths from cardiovascular disease and myocardial infarction, the elderly, illiterates, and people living in the South region.

Our findings suggest positive associations between PM_2.5 constituents and cause-specific mortality, particularly for myocardial infarction.