Background: Previous studies have suggested that exposure to ambient air pollutants may adversely affect human health. However, few studies have examined the health effects of exposure to ambient air pollutants in hospitalized patients.
Objectives: To evaluate the association between short-term exposure to ambient air pollutants and exhaled nitric oxide fraction (FeNO) in a large cohort of hospitalized patients.
Methods: FeNO was detected for 2986 hospitalized patients (ages 18-88 years). Daily average concentrations of SO2, NO2, O3, CO, PM2.5 and PM10 in 2014 and 2015 were obtained from nine fixed-site monitoring stations. Multiple linear regression models were chosen to assess the associations of exposure to ambient air pollutants with FeNO while adjusting for confounding variables. Lagged variable models were selected to determine the association between FeNO and ambient air pollutants concentrations with lags of up to 7 days prior to FeNO testing.
Results: Interquartile-range (IQR) increases in the daily average SO2 (8.00 μg/m3) and PM2.5 (37.0 μg/m3) were strongly associated with increases in FeNO, with increases of 3.41% [95% confidence interval (CI), 0.94-5.93%] and 2.72% (95%CI, -0.09% to 5.61%), respectively. However, FeNO levels were not statistically associated with PM10, NO2, O3 or CO. In the two-pollutant models, the maximum correlation was for ambient SO2. We also found that FeNO was associated with IQR increases in daily average ambient concentrations of SO2 up to 3 and 4 days after the exposure events.
Conclusions: Short-term exposure to SO2 and PM2.5 were positively correlated with FeNO levels in hospitalized patients in Shanghai.
Keywords: Ambient air pollutants; Exhaled nitric oxide; Hospital patients; Respiratory system diseases.
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