Objective  To explore acute effect of ambient air particulate matter on hospital emergency room visits in Yichang city, Hubei province.

  Methods  We collected daily data on emergency services, mean concentration of fine particulate matter (particulate matter less than 2.5 μm in aerodynamic diameter, PM_2.5) and inhalable particulate matter (particulate matter less than 10 μm in aerodynamic diameter, PM₁₀), and meteorological conditions in Yichang city from January 2014 through December 2017. Generalized additive model (GAM) was used to analyze associations between PM_2.5, PM₁₀ and the numbers of non-traumatic, respiratory and cardiovascular emergency room visits.

  Results  During the 4-year period in the city, the average daily concentration of PM_2.5 and PM₁₀ were 72.2 ± 50.7 μg/m³ and 107.6 ± 60.9 μg/m³; the mean daily numbers of non-traumatic, respiratory, and cardiovascular emergency room visits were 33.3 ± 8.6, 2.6 ± 2.2, and 5.1 ± 3.4, respectively. There were significantly positive correlations between daily concentration of PM_2.5, PM₁₀ and the number of non-traumatic, respiratory and cardiovascular emergency room visits (P < 0.05 for all). The results of GAM model analysis demonstrated that a 10 μg/m³ increase in average daily PM_2.5 concentration was related to the increases of 0.41% (95% confidence interval 95% CI: 0.10% – 0.72%), 1.63% (95% CI: 0.62% – 2.64%), and 0.93% (95% CI: 0.17% – 1.69%) in the numbers of non-traumatic, respiratory, and cardiovascular emergency room visits in the same day and for every 10 μg/m³ increase in in average daily PM₁₀, the number of respiratory and cardiovascular emergency room visits in the same day increased by 1.30% (95% CI: 0.50% – 2.11%) and 0.73% (95% CI: 0.13% – 1.34%), respectively.

  Conclusion  Increased daily concentration of PM_2.5 and PM₁₀ may lead to a significant increase in the number of non-traumatic, respiratory and cardiovascular emergency room visits.