Associations between sulfur dioxide exposure and mortality, with a focus on cardiovascular disease: a multi-county...

Despite growing evidence on health effects associated with atmospheric pollutants, limited research has investigated the effect of ambient sulfur dioxide (SO₂) on disease-specific mortality, particularly cardiovascular disease (CVD).

We evaluated the effect of SO₂ on CVD mortality in 122 counties, Hunan Province, Central China, during the period 2018-2022. Daily mortality records and ambient air pollution concentrations were collected, and time-series regression models combined with multilevel meta-analyses were utilized for data analysis.

A total of 2.21 million all-cause deaths were recorded, with CVD accounting for 1.15 million cases. The annual average SO₂ concentration exhibited a significant decline, decreasing from 11.30 µg/m³ in 2018 to 8.08 µg/m³ in 2022, with an overall mean concentration of 9.39 µg/m³. The relative risk (RR) for per 10 µg/m³ increase in SO₂ at lag03 were 1.0258 (95% CI: 1.0033, 1.0488) for CVD and 1.0346 (95% CI: 1.0092, 1.0607) for ischaemic heart disease, respectively. Ambient exposure to SO₂ was linked to an excess mortality fraction of 2.52% (95% CI: 2.17%, 2.84%) for CVD, with a decline from 3.11% (95% CI: 2.66%, 3.49%) in 2018 to 2.17% (95% CI: 1.86%, 2.44%) in 2022. For ischaemic heart disease, the excess mortality fraction was 3.13% (95% CI: 2.87%, 3.37%). After adjustment for co-pollutants such as PM₁₀, PM_2.5 or NO₂, the effect of SO₂ on CVD mortality remained significant and was even enhanced.

The results highlight the importance of continued air quality improvements and targeted public health interventions to mitigate the burden of CVD mortality associated with SO₂.