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

Abstract

Background: 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.

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

Methods: 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.

Results: 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.

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

Keywords: Cause-specific mortality; China; PM(2.5) constituents; Vulnerable population.