Recent evidence for adverse effects of residential proximity to traffic sources on asthma.
OBJECTIVE
A growing body of evidence indicates that residential proximity to traffic sources increases the risk for asthma and asthma exacerbations. In this review we have considered publications from 2006-2007 that examined the impact of residential traffic-related exposures on asthma occurrence and severity.


RESULTS
In these studies, exposures were estimated using traffic metrics based on residential distances from major roads and freeways, traffic densities around homes, and models of traffic exposure. Overall, residential proximity to traffic sources was associated with increased asthma occurrence and exacerbations in both children and adults. Land-use regression models were superior to individual traffic metrics in explaining the variability of traffic-related pollutants. Susceptibility may also play a role in variation in the effects of traffic on asthma.


CONCLUSIONS
There is consistent evidence that living near traffic sources is associated with asthma occurrence and exacerbations. Future studies have the opportunity to improve exposure estimates by measuring traffic-related pollutants near homes and schools and including time/activity patterns in prediction models. Further research is also warranted to investigate the differential impact of traffic by genetic and other susceptibility factors and to identify specific pollutants that underlie the adverse effect of traffic on asthma.
Department of Preventive Medicine, University of Southern California Keck School of Medicine, Los Angeles, California 90033, USA.
Muhammad T
MT
Salam
Talat
T
Islam
Frank D
FD
Gilliland
D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000633:toxicity*; D001249:Asthma / Q000139:chemically induced* / Q000453:epidemiology / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D016021:Epidemiologic Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D007223:Infant; D008875:Middle Aged; D012307:Risk Factors; D001335:Vehicle Emissions / Q000633:toxicity*
D000393:Air Pollutants; D001335:Vehicle Emissions