Impact of acute temperature and air pollution exposures on adult lung function: A panel study of asthmatics

BACKGROUND: Individuals with respiratory conditions, such as asthma, are particularly susceptible to adverse health effects associated with higher levels of ambient air pollution and temperature. This study evaluates whether hourly levels of fine particulate matter (PM(2.5)) and dry bulb globe temperature (DBGT) are associated with the lung function of adult participants with asthma. METHODS AND FINDINGS: Global positioning system (GPS) location, respiratory function (measured as forced expiratory volume at 1 second (FEV(1))), and self-reports of asthma medication usage and symptoms were collected as part of the Exposure, Location, and Lung Function (ELF) study. Hourly ambient PM(2.5) and DBGT exposures were estimated by integrating air quality and temperature public records with time-activity patterns using GPS coordinates for each participant (n = 35). The relationships between acute PM(2.5), DBGT, rescue bronchodilator use, and lung function collected in one week periods and over two seasons (summer/winter) were analyzed by multivariate regression, using different exposure time frames. In separate models, increasing levels in PM(2.5), but not DBGT, were associated with rescue bronchodilator use. Conversely DBGT, but not PM(2.5), had a significant association with FEV(1). When DBGT and PM(2.5) exposures were placed in the same model, the strongest association between cumulative PM(2.5) exposures and the use of rescue bronchodilator was identified at the 0–24 hours (OR = 1.030; 95% CI = 1.012–1.049; p-value = 0.001) and 0–48 hours (OR = 1.030; 95% CI = 1.013–1.057; p-value = 0.001) prior to lung function measure. Conversely, DBGT exposure at 0 hours (β = 3.257; SE = 0.879; p-value>0.001) and 0–6 hours (β = 2.885; SE = 0.903; p-value = 0.001) hours before a reading were associated with FEV(1). No significant interactions between DBGT and PM(2.5) were observed for rescue bronchodilator use or FEV(1). CONCLUSIONS: Short-term increases in PM(2.5) were associated with increased rescue bronchodilator use, while DBGT was associated with higher lung function (i.e. FEV(1)). Further studies are needed to continue to elucidate the mechanisms of acute exposure to PM(2.5) and DBGT on lung function in asthmatics.