Effects of personal exposure to nitrogen dioxide on peak expiratory flow in asthmatic patients

Abstract

Objectives: Nitrogen dioxide (NO2) has been inconsistently associated with gradual decreases in lung function. Here, we studied the effects of NO2 exposure in asthmatics by examining the association between changes in lung function and concentrations of NO2 which were personally measured. Methods: Peak expiratory flow (PEF) and daily personal exposures to NO2 were recorded on 28 patients with asthma (confirmed by methacholine provocation test) over 4 weeks. We used generalized estimating equations to assess the relationship between personal NO2 exposure and PEF, adjusting for potential confounders such as age, gender, outdoor particulate matter, temperature, humidity, and exposure to environmental tobacco smoke. Results: The personal NO2 exposures were higher than the corresponding ambient levels. The mean personal: ambient ratio for NO 2 was 1.48. The personal NO2 exposures were not associated with the morning PEF, evening PEF, or the diurnal PEF variability. However, environmental tobacco smoke was negatively associated with both the morning and evening PEF. Conclusions: Among the asthmatic adults who participated in this study, we found no apparent impact of personal NO2 exposures on the peak expiratory flow.