COMMENTARY

Traffic-Related Air Pollution and Lung Growth in Very Young Children

Nicholas Gross, MD, PhD

Disclosures

December 31, 2012

Traffic-Related Air Pollution and Lung Function in Children at 8 Years of Age -- A Birth Cohort Study

Schultz ES, Gruzieva O, Bellander T, et al
Am J Respir Crit Care Med. 2012;186:1286-1291

Introduction

Long-term exposure to air pollutants is associated with decrements in lung function in children. However, its effects in very young children are not well known, nor is it known whether there is a time when the growing lung is more vulnerable to the effects of urban air pollution.

To address this question, a cohort of 1900 children in Sweden was prospectively studied using serial questionnaires of their respiratory health and allergies from the first year of life to 8 years of age. Their exposure to ambient particulate matter, predominantly diesel soot, was derived from continuous monitoring of airborne fine particles and the location of the home and school of each child. At age 8 years, the children performed spirometry and received blood tests and a clinical examination.

The primary outcome of lung function was corrected for such covariates as age, sex, height, a family history of asthma or allergies, and ambient ozone levels.

The mean FEV1 was significantly lower in children exposed to higher ambient levels of particulate matter, and almost all of the decrement was from exposure that occurred in the first year of life. This effect was particularly marked in children who were concomitantly sensitized to common inhalant or food allergies.

The investigators concluded that exposure to traffic-related air pollution very early in life has detrimental effects on long-term lung function, particularly in children with atopy.

Viewpoint

One half of the world's population now lives in urban areas, and that proportion is increasing. At the same time, the number and use of automobiles and other vehicles that employ internal combustion engines is increasing. Thus, urban air quality, like climate change, is a looming concern. The long-term effects of traffic-related pollution on the airways, particularly of children, will need to be reviewed on a continuing basis.

Previous studies of the effects of traffic-related air pollution on children have had mixed results.[1,2,3] Local factors and the age of children studied seem to contribute to the differences found. Those performed in California tend to show an adverse effect,[1] whereas those performed in The Netherlands[2] and Germany[3] seem to show little effect. This can be explained by local differences in the weather and the types and sizes of particulate matter that is predominant in the different locales. Diesel soot has been considered one of the worst forms of traffic-related pollution, from a respiratory standpoint.[4]

The present study includes the youngest cohort of participants to date, and like most previous studies, it tends to show an unfavorable interaction of air pollutants with allergic airways. Clearly, children with asthma are most vulnerable to the harmful effects of air pollution.

A weakness of this study is that, as in previous studies, local factors are important. Findings in Sweden may not apply to children in California, just as findings in California may not apply to children in New York.

Abstract

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