Effects of short-term exposure to air pollution on respiratory symptoms and lung function among patients with asthma

Since air pollution can cause acute exacerbation of asthma, we aimed to investigate the effects of short-term exposure to ambient air pollution on respiratory symptoms and lung function among patients with asthma. A prospective and observational panel study recruited 32 patients with asthma from November 2015 to December 2016. The Asthma Control Test scores and lung function measurements of the patients were repeatedly assessed. Daily ambient air pollution data, including particulate matter (PM2.5 and PM10), sulfur dioxide, nitrogen dioxide, and carbon monoxide, were obtained from nearby central air-monitoring stations. Mixed effects models were used to examine the associations between pollutant exposure and health measurements. Clinical data were repeatedly collected 2 to 13 times each month, totaling 266 visits. Increases in the interquartile ranges of PM2.5 (74.5 μg/m3, 6-day), PM10 (78 μg/m3, 5-day), sulfur dioxide (10 μg/m3, 7-day), nitrogen dioxide (37 μg/m3, 6-day), and carbon monoxide (0.7 mg/m3, 6-day) levels were significantly associated with reductions in Asthma Control Test scores by 3.6%, 2.8%, 3.2%, 3.8%, and 2.9%, respectively. An interquartile range increase of 78 μg/m3 in the 7-day moving average concentration of PM10 was significantly associated with reductions of 3.6% in percentage of predicted forced expiratory volume in 1 second and 6.0% in percentage of predicted forced expiratory flow at 25% of the forced vital capacity, respectively. Short-term ambient air pollution may aggravate respiratory symptoms and cause a decline in lung function among patients with asthma.