A time series analysis of air pollutants and emergency visits in Guiyang, China, 2014-2019

Objective To investigate the influence of short-term air pollutant exposure on emergency visits in Guiyang, China.

Methods Related data of Guiyang from 2014 to 2019 were collected, including daily mean concentrations of air pollutants (PM₁₀, PM_2.5, SO₂, NO₂, CO, and O_{3-8 h}), daily mean temperature, relative humidity and daily emergency visits. The generalized additive model in time series analysis was used to establish a single-pollutant model and a multi-pollutant model, and the maximum effective value of lag days was used as the excessive risk to analyze the effect of air pollutants on daily emergency visits.

Results The daily mean concentrations of NO₂, SO₂, CO, O_{3-8 h}, PM₁₀ and PM_2.5 were 25.17, 14.76, 682.19, 75.89, 57.56 and 35.37 μg/m³, respectively, from 2014 to 2019. A total of 57 351 medical records of emergency visits were collected from a grade A tertiary hospital during the study period, with a daily mean number of 26 emergency visits. The single-pollutant model showed that for every 10 μg/m³ increase in the concentrations of NO₂, SO₂, CO, O_{3-8 h}, PM₁₀ and PM_2.5, the excessive risk of emergency visits were 4.36% (95% CI: 1.66%-7.14%), 3.24% (95% CI: 0.13%-6.46%), 0.17% (95% CI: 0.06%-0.28%), 1.28% (95% CI: 0.64%-1.94%), 0.56% (95% CI: 0.092%-1.04%) and 0.81% (95% CI: 0.086%-1.55%), respectively. In the multi-pollutant model with adjustment for other pollutants, only NO₂ and O_{3-8 h} were significantly associated with emergency visits, with an excess risk of 3.26 (95% CI: 0.38%-6.22%) and 1.33 (95% CI: 0.63%-2.30%), respectively.

Conclusion Short-term exposure to air pollutants in Guiyang from 2014 to 2019 affects emergency visits, among which NO₂ and O_{3-8 h} tend to have a greater influence.