A Case-crossover Study on Air Pollution and Outpatient Visits for Respiratory Diseases

Objective To explore the impact of short-term exposure to air pollutants on outpatient visits for respiratory diseases.

Methods Daily concentration of air pollutants, meteorological data and the count of outpatient visits for respiratory diseases from a general hospital in Beijing during the period from 1 January 2014 to 31 December 2015 were collected. A time-stratified case-crossover design was used to evaluate the associations between air pollution and outpatient visits for respiratory diseases.

Results After adjusting for meteorological variables, effect of the concentration of air pollutants on outpatient visits for respiratory diseases was the strongest on the same day. A 10 μg/m³ increase of PM_2.5, PM₁₀, NO₂ and SO₂ was associated with an increase of outpatient visits for respiratory diseases on an odd ratios values of 1.0066 (95%CI:1.005 8~1.007 5), 1.004 8(95%CI:1.004 1~1.005 6), 1.025 9(95%CI:1.023 7~1.028 0) and 1.022 9(95%CI:1.019 8~1.025 9) respectively.

Conclusion Short-term elevation of ambient air pollutants might induce an increase of daily outpatient visits for respiratory diseases.