Ambient sulfur dioxide and years of life lost from stroke in China: a time-series analysis in 48 cities

Abstract

Background and objectives: Sulfur dioxide (SO₂) is a ubiquitous air pollutant and its concentration in China remains at a higher level in the world. However, evidence regarding short-term effect of SO₂ on years of life lost (YLL) from stroke is scarce. We aim to estimate the short-term association between SO₂ pollution and YLL for stroke and the related excess life years and economic loss.

Methods: A national time-series study was conducted in 48 Chinese cities from 2013 to 2017. Generalized additive model coupled with random-effects model were used to explore the effects of SO₂ on YLL from stroke. Stratified analyses were performed by demographical and geographical factors, and the effect modification of city-level factors was estimated. In addition, the related economic loss was calculated using the method of the value per statistical life year (VSLY).

Results: Averaged daily mean SO₂ concentration was 27.1 μg/m³ in 48 Chinese cities from 2013 to 2017. Per 10 μg/m³ increase in the concentration of SO₂ (lag03) was associated with an increment of 0.70% (95% confidence interval: 0.27%,1.13%), 0.51% (-0.01%,1.04%), 0.71% (0.14%,1.28%) increase in YLL from total stroke, hemorrhagic and ischemic stroke, respectively. The effect of short-term ambient SO₂ exposure on YLL from stroke was more pronounced in the less-educated population and those living in the south. The corresponding excess economic loss during the study period due to SO₂-related YLL from stroke accounted for 0.08% (0.03%, 0.13%) of the GDP in China.

Conclusions: Our results provide evidence from China that short-term exposure to SO₂ is positively associated with YLL from stroke and its major subtypes in certain subgroups of population. This study calls for greater awareness of the adverse health effect due to SO₂ in China and other developing countries, as well as local-specific implementation of air pollution mitigation measures.

Keywords: Economic loss; Effect modification; Stratified analyses; Stroke; Sulfur dioxide; Years of life lost.