Objective To study the connections between PM 2.5 in the air in Jinan city and the outpatient visits in the department of pneumology, the department of cardiology and the department of neurology. Methods Outpatient visits in the department of pneumology, department of cardiology and department of neurology in two comprehensive hospitals in Jinan, air quality and meteorological data were collected. On the basis of controlling confounding factors such as "day of the week" and meteorological data, generalized additive poisson regression model was applied to analyze the effect of PM 2.5 on the outpatients visits. Results While two-day cumulative PM 2.5 was lower than 200 μg/m3, the increase of outpatients visits in the department of pneumology was not substantial along with the increase of PM 2.5. While PM 2.5 was higher than 200 μg/m3 and lower than 400 μg/m3, the outpatient visits were large. Concentration of PM 2.5 in the atmosphere showed a non-linear connection with daily outpatients visits in the Department of Pneumology. Concentra-tion of two-day cumulative PM 2.5 showed a linear connection with the outpatient visits in department of cardiology and department of neurology. Once the two-day cumulative PM 2.5 increased 1 μg/m3, 1 more patient visited the out-patient of department of cardiology and department of neurology. Conclusion With the increase of PM 2.5 concentra-tion in the air, outpatient visits in the department of pneumology, the department of cardiology and the department of neurology have an increasing trend, but the concentration of PM 2.5 has slight different connections with the daily out-patient visits in different departments.