Relationship between Radical Generation by Urban Ambient Particulate Matter and Pulmonary Function of School Children

Abstract

The mechanisms by which particulate matter (PM) produces adverse effects on the respiratory system, such as pulmonary dysfunction in children, are largely unknown. However, oxidative stress is thought to play an important role. Various chemical compounds in ambient particulate matter, including transition metals and aromatic organic compounds, may contribute to adverse effects through intrinsic generation of reactive oxygen species (ROS). It was hypothesized that ROS generation by PM, as determined through electron spin resonance (ESR) spectroscopy, may be negatively associated with pulmonary function in school children. PM_2.5, PM₁₀, and total suspended particulates (TSP) were sampled at the playgrounds of six elementary schools in the city of Maastricht, the Netherlands. All children (8–13 yr) from the six schools were asked to undergo spirometry. Multivariate linear regression models were constructed to evaluate associations between oxygen radical formation by PM and lung function. The radical-generating capacity per microgram PM correlated negatively to forced expiratory volume in 1 s (FEV₁) and forced expiratory flow at 50% (FEF_50%) of forced vital capacity (FVC). The data indicate that chemical features that contribute to intrinsic generation of ROS may be relevant for PM risk assessment.

We kindly thank G. Swaen (Epidemiology, Maastricht University) and J. Meijers (GGD-ZZL, Maastricht) for their advice in the conceptualization stage of this study and their participation in the advisory board of the study; Arnold Kester (Statistics, Maastricht University) for his advice on random effects modeling; the school boards, participating children, and their parents for their cooperation; and C. Vossen, H. Driece, and C. op den Camp for their contribution to the implementation of the study. This study was supported by a grant from Astra Zeneca Netherlands.