Background

Evidence linking mortality and short-term exposure to particulate matter (PM_2.5) constituents was sparse. The mortality displacement was often unconsidered and may induce incorrect risk estimation.

Objectives

To assess the short-term effects of PM_2.5 constituents on all-cause mortality considering the mortality displacement.

Methods

Daily data on all-cause mortality and PM_2.5 constituents, including sulfate (SO₄²⁻), nitrate (NO₃⁻), ammonium (NH₄⁺), organic matters (OM), and black carbon (BC), were collected from 2009 to 2020. The mortality effect of PM_2.5 and its constituents was estimated using a distributed lag non-linear model. Stratified analyses were performed by age, sex, and season.

Results

Per interquartile range increases in SO₄²⁻, NO₃⁻, NH₄⁺, OM, and BC were associated with the 1.42% (95%CI: 0.98, 1.87), 3.76% (3.34, 4.16), 2.26% (1.70, 2.83), 2.36% (2.02, 2.70), and 1.26% (0.91, 1.61) increases in all-cause mortality, respectively. Mortality displacements were observed for PM_2.5, SO₄²⁻, NH₄⁺, OM, and BC, with their overall effects lasting for 7–15 days. Stratified analyses revealed a higher risk for old adults (>65 years) and females, with stronger effects in the cold season.

Conclusions

Short-term exposures to PM_2.5 constituents were positively associated with increased risks of mortality. The mortality displacement should be considered in future epidemiological studies on PM constituents.

Data availability

Data will be made available on request.