The impacts of continuous improvements in air quality on mortality in Beijing: A longitudinal comparative study

There has been increasing concern about the health effects of air pollution in China, and many measures have been implemented to control air pollution. To investigate the impacts of air quality improvement on mortality from non-accidental causes (NAD), cardiovascular disease (CD), and respiratory disease (RD), a longitudinal comparative study was conducted in Beijing. This study investigated the effects of air pollutants on outcomes across five periods (stages 1-5). Health effect data from stage1-5 (1990-2013) were obtained through a systematic literature search of studies published before 2021. Daily atmospheric pollutant, meteorological, and cause-specific death data were collected to determine the effects in stage 5 (2015-2017). Poisson generalized additive models were used to analyze the associations between short-term exposure to air pollutants and mortality. Random-effects meta-analysis models were used to estimate the pooled effects at each stage. The effects of changes in air quality were analyzed through a difference-in-differences approach. Our results indicate that the absolute change of concentrations of sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and particulate matter with aerodynamic diameter≤ 10 μm (PM₁₀₎ and≤ 2.5 μm (PM_2.5) decreased by up to 42%, 10%, 33%, and 15% (stage 5), respectively. The effects of SO₂ on deaths from CD and RD decreased by up to 2.76% and 1.43% (stage 3). The effects of NO₂ on mortality from NAD, CD, and RD decreased by up to 0.39%, 0.74%, and 0.37% (stage 5). The effects of PM₁₀ on death decreased by up to 0.11% (stage 3). The effects of PM_2.5 on deaths from CD and RD decreased by up to 0.33% and 0.13% (stage 5). The results indicate that continued improvements in air quality have reduced the acute impact of air pollutants on population health.