Objective To explore the effects of exposure to atmospheric particulate matters (PM_2.5, PM₁₀) on the outpatient visits of adult internal medicine in Hefei, Anhui province, China.

Methods Daily air pollutant monitoring data, meteorological data, and outpatient visits of adult internal medicine in Hefei from 2016 to 2018 were collected. Controlling for the temporal trend, meteorological factors, and day-of-the-week effect, a time series analysis using a generalized additive model(GAM) was applied to evaluating the effects of the concentrations of atmospheric particulates on the outpatient visits, including lag effect (lag0 d to lag7 d) and cumulative lag effect (lag01 d to lag07 d), and analyzing how other pollutants affected the effects. The excess risk (ER) of the increased outpatient visits and its 95%CI were calculated for every 10 μg/m³ increase in particulate concentrations.

Results The increased contentrations of atmospheric particulates were associated with the elevated daily outpatient visits of adult internal medicine in Hefei. Every 10 μg/m³ increase in PM_2.5 concentration showed the strongest effects on the total daily visits on lag04, the daily visits of respiratory on lag07 d, and the daily visits of cardiovascular on lag04 d, with ER (95%CI) being 1.04% (0.39%-1.70%), 0.74% (0.06%-1.43%), and 2.61% (1.27%-3.96%), respectively. Every 10 μg/m³ increase in PM₁₀ concentration had the strongest effects on the total daily visits on lag0 d and the daily visits of respiratory on lag07 d, with ER (95%CI) being 0.41% (0.06%-0.76%) and 0.77% (0.29%-1.26%), respectively.

Conclusion The increase in the concentrations of PM_2.5 and PM₁₀ may increase the outpatient visits of adult internal medicine in Hefei, and have a lag effect.