Association between Respiratory Symptoms, Ozone, and Fine Particulates in a Diverse New England Population

Abstract

Background:

Exposure to ambient ozone (O₃) and fine particulates (PM_2.5) in levels at or below United States Environmental Protection Agency health standards is a growing concern. Previous research in relatively low air pollution areas has focused on asthmatic participants and has been based on single study locations.

Objective:

To examine the association between relatively low ambient concentrations of O₃ and PM_2.5 on daily respiratory systems in a diverse New England population.

Methods and Participants:

Daily respiratory symptoms data were collected from a diverse group of 168 participants during July and August 2004 in New England. Generalized linear mixed effect models were used to estimate effects from outdoor ambient O₃ and PM_2.5 on respiratory symptoms.

Results:

In single pollutant models controlled for daily maximum temperature and daily mean relative humidity, significant associations (α=0.05) were found between O₃ and the increased likelihood of experiencing lower respiratory symptoms, and shortness of breath. After three days of elevated O₃, a 10 ppb increase in 1-hour and 8-hour O₃ was associated with increased likelihood of lower respiratory symptoms (by 5-8%), and shortness of breath (by 8-9%) for all and the participants with asthmatic or COPD respectively. A same day 10 μg/m³ increases in mean 24-hour PM_2.5 was associated with increased likelihood of lower respiratory symptoms (by 11-16%), cough by (15-32%), wheeze (by 43-76%) for all and participants with asthmatic or COPD respectively. The level of association was higher in participants with asthmatic or COPD compared to all and otherwise healthy participants.

Conclusions:

Relatively low levels of O₃ and PM_2.5 as measured at an outdoor central site were significantly associated with various respiratory symptoms in participants with asthma or COPD, and all participants combined but not in otherwise healthy participants. Some of the associations persisted for multiple days after the elevated air pollution day. At the same level, however, both O₃ and PM_2.5 were significantly associated with various onsets of symptoms in participants with asthma or COPD, all participants combined, and the otherwise healthy participants. These effects were observed across multiple study locations spanning a gradient of climate and geographic differences.

Authors: A Upadhyay, Prof. C Wake, T Lambert, Prof. E Linder (University of New Hampshire, 2006)