Abstract: Objective To investigate the relationship between air pollutants,including ozone（O₃） and fine particulate matter（PM_2.5） and outpatient visits of respiratory system. Methods The air pollution data from 12 environmental monitoring points in a city of southern Jiangsu from 2021 to 2022,meteorological data during the same period and daily respiratory outpatient data from six monitoring hospitals were collected. A generalized additive model was used to quantitatively analyze the relationship between O₃ and PM_2.5 exposure and respiratory outpatient visits. Results In a city in southern Jiangsu,the average daily outpatient visits of children and adults with respiratory system in 2021 and 2022 were 1 246 and 433,respectively. The O_{3-8 h} average concentration was 109.39 μg/m³,and the average daily concentration of PM_2.5 was 35.15 μg/m³. The single-pollutant model showed that the respiratory outpatient visits in children and adults increased by 0.35%（95%CI：0.26%-0.45%） and 0.81%（95%CI：0.64%-0.98%）for every 10 μg/m³ increase in O₃（Lag03）. However,for every 10 μg/m³ increase of PM_2.5（Lag07）,the number of respiratory outpatient visits in children and adults increased by 8.13%（95%CI：7.88%-8.39%） and 6.46%（95%CI：6.06%-6.87%）,respectively.The multi-pollutant model showed that O₃ alone introduced NO₂ and simultaneously introduced SO₂,NO₂,CO and PM₁₀ increased the risk of excess respiratory outpatient visits in both children and adults. When SO₂,NO₂,CO and PM₁₀ were introduced separately and simultaneously with PM_2.5,the risk of excess respiratory outpatient visits was reduced in both children and adults. Conclusion There was a positive correlation between the increase of atmospheric O₃ and PM_2.5 concentration and the outpatient visits of respiratory system,and children were more sensitive to the increase of PM_2.5 concentration.

Key words: Ozone, Fine particulate matter, Respiratory diseases, Outpatient volume, Generalized additive model