California Air Resources Board

SACRAMENTO - New research supports a growing body of scientific literature indicating that sensitive populations, including children, certain ethnic groups and people of lower socioeconomic status, are more vulnerable to the effects of high exposures to traffic-related air pollution.

The University of California Irvine study, which examined the effect of chronic exposure in asthmatic children living in homes near traffic pollution, was led by Ralph J. Delfino, M.D., Ph.D, at the Department of Epidemiology. The study was funded by the Air Resources Board and benefited from funding by the South Coast Air Quality Management District. 

Overall, acute worsening of asthma was associated with short-term elevations of air pollution, particularly in asthmatic children living near high traffic roadways. It is the first study to show increased sensitivity to daily air pollution exposures in asthmatic children living in homes in areas with higher levels of air pollution from traffic, compared to asthmatic children exposed to lower levels of traffic-related pollution. 

While numerous studies have linked fine particulate pollution (known as PM2.5) exposures to respiratory illnesses, including asthma, there is a lack of information about the health effects of exposure to particulate pollution from different sources. Assessing the health impacts from exposure to fine particle pollution from a variety of important sources could help ARB to better target sources of PM2.5 for future control measures. 

Researchers will discuss their findings during an ARB-hosted research seminar and webcast open to the public at 1:30 p.m. (PDT) April 7. For more information, click here. The webinar will be archived on ARB’s website.

The Irvine study looked at possible relationships between worsening asthma – specifically increased asthma-related emergency room visits and hospital admissions – and exposure to PM2.5, including primary (combustion emissions) and secondary (photochemically produced) components of PM2.5, traffic pollution, and ambient pollutant gases in asthmatic children in Orange County. Research data included 11,390 emergency room visits and hospital admissions made by 7,954 children ages 0 to 18 between 2000 and 2008. 

Key findings included:

• Associations of asthma with ambient pollution, including carbon monoxide, oxides of nitrogen and PM2.5, were stronger among children exposed to high traffic-related air pollution at their homes, suggesting this is a vulnerable population. 
• Hospital encounters for asthma were linked to PM2.5 and ozone in warm months, and with PM2.5, carbon monoxide, nitrogen dioxide and oxides of nitrogen in the cool season. 
• Hispanic and African American children, as well as those without private insurance, tended to live in areas associated with higher levels of traffic-related air pollution, further increasing their vulnerability.

Results of the study, “Risk of Pediatric Asthma Morbidity from Multi-Pollution Exposures,” provide additional evidence to support ARB’s regulations to reduce traffic-related air pollution.