Correlations between atmospheric PM_2.5 and residents' circulatory disease deaths in Zhengzhou

Background Exposure to air pollutant PM_2.5 is closely related to the number of deaths from circulatory diseases, but the impact varies among cities.

Objective This study focuses on the correlation between PM_2.5 concentration and average daily deaths from circulatory diseases of residents in Zhengzhou.

Methods Data of air pollutants, meteorological variables, and death of Zhengzhou residents in 2019 were collected. Spearman correlation analysis was used to understand the correlations among the variables. Poisson generalized linear model was employed, after controlling covariates such as long-term trend, day-of-the-week effect, and meteorological factors, to evaluate the daily circulatory disease deaths associated with atmospheric PM_2.5concentrations and the lag effect. Age- and season-stratified analyses were also conducted.

Results A total of 19 429 people died of circulatory diseases in Zhengzhou in 2019, with an average of 55.32±13.35 people every day. The average annual concentration of PM_2.5 in Zhengzhou was (65.81±41.10) μg·m^-3 in 2019. The Spearman correlation analysis results showed that the average daily death number of circulatory diseases was positively correlated with PM_2.5, PM₁₀, SO₂, NO₂, CO, and air pressure, and negatively correlated with O_3-8h, average daily temperature, and relative humidity (P < 0.05). In the single-pollutant model, the correlations between PM_2.5 concentration and deaths from circulatory diseases in total, < 65 years old, and ≥ 65 years old populations were strongest at lag2, lag4, and lag3, and for every 10μg·m^-3 increase in the concentration of PM_2.5, the risk of daily mortality increased by 0.472% (95% CI: 0.098%-0.847%), 0.700% (95% CI: 0.059%-1.345%), and 0.516% (95% CI: 0.097%-0.937%), respectively. The curve of the exposureresponse relationship between PM_2.5 concentration and circulatory disease deaths showed an approximate linear rise. In both heating and non-heating periods, every 10 μg·m^-3 increase in PM_2.5 concentration was associated with an increase in daily mortality risk of circulatory system diseases in the total population by 0.665% (95% CI: 0.084%-1.249%) and 1.919% (95% CI: 0.355%-3.506%) respectively (P < 0.05); in the non-heating period, every 10 μg·m^-3 increase in PM_2.5 concentration was associated with an increase in daily mortality risk of circulatory diseases in the residents ≥ 65 years by 2.734% (95% CI: 0.975%-4.524%) (P < 0.05). In the double-pollutant model, in the heating period, when SO₂ was included, the risk of daily death from circulatory diseases associated with an increase in PM_2.5 concentration was significant in the total population and the people ≥ 65 years (P < 0.05); when O_3-8h was included, the risk was still significant in the total population (P < 0.05). In the non-heating period, when SO₂, CO, PM₁₀, NO₂, and O_3-8h were included respectively, the effect of PM_2.5 concentration increase on the daily mortality risk of circulatory diseases was still significant in the total population and the people ≥ 65 years (P < 0.05).

Conclusion The increase of PM_2.5 concentration is positively correlated with the increase of the risk of death from circulatory diseases among residents in Zhengzhou; the elderly deserve special attention.