Dr. W. James Gauderman is a researcher in the Department of Preventive Medicine at the University of Southern California School of Medicine.

1. Dr. Gauderman, what drove you and your colleagues to pursue this line of research into the effects of air pollutants on the respiratory development of children and young adults?

"Despite advances over the last few decades to improve air quality in the United States, millions of children still live in communities with relatively high levels of one or more air pollutants. It is well known that short-term exposure to polluted air can cause acute health effects, including watery eyes, tightness in the chest, and short-term reductions in lung function. However, at the time we began our study in 1993, little was known about possible chronic, long term effects of breathing polluted air on the respiratory health of children. To address this gap in knowledge, we recruited children from 12 southern California communities, representing a broad range of air quality, and documented their respiratory health over an 8 year period, from 4th grade to 12th grade. One of our primary outcomes, and the focus of the current paper, was lung development as measured by growth in lung function over the 8 year period."

2. What do you hope will follow this research? Do you foresee any changes in reduced-emission policies on a state-wide or national level?

"The conclusion one can draw from our study and other studies of air pollution and health is clear: current levels of outdoor air pollution are associated with adverse health effects. We anticipate that our results will be used by the United States Environmental Protection Agency (EPA) and other national and international agencies to justify continued emphasis on improving air quality. Reduced emissions from vehicles and industrial sources will be necessary to counteract the projected growth in populations in many urban areas. For example, in southern California there are current projections that the ports of Los Angeles and Long Beach (in combination, the largest ports in the nation) will triple in the volume of cargo they handle over the next 15-20 years. These ports are the single largest source of pollution in the Los Angeles area. Added to this large point source are the increasing numbers of trains and diesel trucks required to move the incoming cargo to local and national destinations.

It follows that this increase in the number of pollution sources must be balanced with a corresponding reduction in emissions from these sources, just to maintain current air quality. In fact, our results suggest that maintaining current air quality is not sufficient, and that we need to move towards strategies that reduce pollutant levels in the face of an increasing population size. One needs to only look at the last three decades to know that this is quite possible. In the greater Los Angeles basin, for example, pollutant levels have decreased dramatically from the 1960's and 1970's to the current time, despite equally dramatic increases in the number of vehicle miles traveled over that time. Our results indicate that continued improvements will have beneficial health impacts. We hope that our results will emphasize the need to consider the health impacts of air pollution as we continue to develop our urban population centers."

3. Lastly, what message would you like current premed and medical students to learn from the results of your research?

"Based on our results and the results of others that have studied air pollution effects, the practicing physician should be aware that children living in polluted environments are more likely than children in low-pollution areas to have poor respiratory health. Our analysis of attained lung function at age 18 (see Figure 3) demonstrates that breathing polluted air during adolescence is associated with a significant increase in the fraction of young adults with clinically low (below 80% of predicted) lung function. These individuals are likely to suffer more severe symptoms during viral infections, and ultimately may be at increased risk for respiratory and cardiovascular complications in later adulthood. In addition to associations with low lung function, we have previously demonstrated links between air pollution and new-onset asthma (1), respiratory symptoms in asthmatics (2), and absence from school due to respiratory illness (3). We obviously cannot tell children to avoid breathing polluted outdoor air. However, knowing the impact that pollution can have may enable physicians to consider air quality issues as part of their diagnosis and treatment strategy. Furthermore, the physician may also advise a child with a respiratory condition to limit vigorous outdoor exercise on particularly smoggy days, or to avoid playing near major sources of pollution such as a busy freeway."

References:

1. McConnell R, Berhane K, Gilliland F, London SJ, Islam T, Gauderman WJ, Avol E, Margolis HG, Peters JM. Asthma in exercising children exposed to ozone: a cohort study. Lancet. 359:386-91, 2002.

2. McConnell R, Berhane K, Gilliland F, Molitor J, Thomas D, Lurmann F, Avol E, Gauderman WJ, Peters J. Prospective study of air pollution and bronchitic symptoms in children with asthma. Am J Resp Crit Care Med, 168:790-97, 2003.

3. Gilliland FD, Berhane K, Rappaport E, Thomas DC, Avol E, Gauderman WJ, London SJ, Margolis HG, McConnell R, Islam KT, Peters JM. The effects of ambient air pollution on school absenteeism due to respiratory illness. Epidemiology, 12:43-54, 2001.

Lester Y. Leung is the Editor-in-Chief of The Next Generation and a member of the Harvard College Class of 2006.

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