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The exposure metric choices have significant impact on the association between short-term exposure to outdoor particulate matter and changes in lung function: Findings from a panel study in chronic obstructive pulmonary disease patients

Ni, Yang, Wu, Shaowei, Ji, Wenjing, Chen, Yahong, Zhao, Bin, Shi, Shanshan, Tu, Xingying, Li, Hongyu, Pan, Lu, Deng, Furong, Guo, Xinbiao
The Science of the total environment 2016 v.542 pp. 264-270
acute exposure, air, air pollution, confidence interval, dose response, lung function, particulates, patients, pollutants, respiratory tract diseases, time-weighted average
The use of ambient air pollution data obtained from central air-monitoring stations as surrogates for participants' exposures to outdoor air pollutants in previous studies may have introduced bias in the estimation of exposure–response associations.We investigated and compared the effects of short-term exposure to outdoor particulate matter (PMout) and outdoor-originated equivalent personal PM (PMeq) on lung function in chronic obstructive pulmonary disease (COPD) patients.A total of 33 doctor-diagnosed stable COPD patients were recruited and repeatedly measured for lung function (totally 170 measurements) in 2013–2014. Daily PMout concentrations were obtained from central-monitoring stations, and daily time-weighted average PMeq concentrations were estimated based on PMout over the study. Associations of PM with lung function were estimated using mixed-effects models.Interquartile range increases in PM2.5out (111.0μg/m3, 5-day) and PM10out (112.0μg/m3, 3-day) were associated with a 3.3% (95% confidence interval [CI]: −5.8%, −0.8%) reduction and a 2.1% (95%CI: −3.9%, −0.3%) reduction in forced vital capacity (FVC), respectively. Similar results were found for forced expiratory volume in 1s (FEV1). An interquartile range increase in PM2.5eq (45.3μg/m3, 3-day), but not PM10eq, was still associated with a 1.7% (95%CI: −3.3%, −0.1%) reduction in FVC.Our study may provide a novel approach to assess the association of ambient PM with health observations with improved accuracy.