Low Levels of Particle Air Pollution Effect Children with Asthma

. Dales, L. Chen, A. M. Frescura, L. Liu, and P. J. Villeneuve Acute effects of outdoor air pollution on forced expiratory volume in 1 s: a panel study of schoolchildren with asthma
Eur Respir J 2009 34: 316-323.

¹ University of Ottawa, ² Ottawa Hospital Research Insitute, ³ Air Health Effects Research Section, Biostatistics and Epidemiology Division, Environmental Health Science and Research Bureau, Health Canada, and ⁴ Immunization and Respiratory Infections Division, Public Health Agency of Canada, Ottawa, ON, Canada.

CORRESPONDENCE: R. Dales, Air Health Effects Research Section, Biostatistics and Epidemiology Division, Environmental Health Science and Research Bureau, Health Canada, 3rd Floor, Room 3-039, P.L. 4903B, 269 Laurier Avenue W, Ottawa, K1A 0K9, ON, Canada. E-mail: rdales@ohri.ca

Keywords: Air pollution, children, environment, lung function

Received: September 9, 2008
Accepted February 5, 2009

Urban air pollution has been associated with morbidity but little information exists on how it affects diurnal variation of lung function in children with asthma. The purpose of this study was to investigate the acute effects of traffic-related pollution on lung function among children with asthma.

We recorded morning and evening forced expiratory volume in 1 s (FEV₁) for 28 consecutive days in 182 elementary schoolchildren with physician-diagnosed asthma, and monitored ambient hourly air pollution concentrations.

An interquartile range (IQR) increase (6.0 µg·m^–3) in the previous 24-h (20:00 h to 20:00 h) mean concentration of fine particulate matter 2.5 µm in diameter (PM_2.5) was associated with a 0.54% (95% confidence interval (CI) 0.06–1.02) decrease in bedtime FEV₁ (p = 0.027). This association persisted in two-pollutant models with ozone, nitrogen dioxide and sulphur dioxide. An IQR increase in mean daytime (08:00 h to 20:00 h) PM_2.5 of 6.5 µg·m^–3 was associated with a 0.73% (95% CI 0.10–1.37) decrease in FEV₁ over the course of the day expressed as 100x(FEV₁ bedtime – FEV₁ morning)/FEV₁ morning (p = 0.024).

This study suggests that, in children with asthma, relatively low concentrations of urban air pollution worsen lung function over a short period of time, even within a day. Of the pollutants measured, PM_2.5 appears to be the most important.