USC study examines nearroadway air pollution as
contributor to asthma
Leslie Ridgeway [/author/leslie-ridgeway/]
SEPTEMBER 25, 2012
Research conducted at USC indicates that at least 8
percent of the more than 300,000 cases of
childhood asthma in Los Angeles County can be
attributed to traffic-related pollution at homes
within 75 meters â€” a little less than 250 feet â€” of a
The study, which focused on the Los Angeles basin,
also indicated that previous estimates of childhood
asthma exacerbation related to air pollution may
have underestimated the true burden of exposure
The research, which was published online Sept. 24
in Environmental Health Perspectives, was
conducted in collaboration with the Swiss Tropical
and Public Health Institute and Sonoma
â€œOur findings suggest that there are large and
previously unappreciated public health consequences of air pollution in Los Angeles
County and probably other metropolitan areas with large numbers of children living near
major traffic corridors,â€ said Rob McConnell, professor of preventive medicine at the Keck
School of Medicine of USC.
â€œPlans to reduce greenhouse gas emissions and
combat climate change offer an opportunity to
develop â€˜win-winâ€™ strategies,” said Rob
McConnell, professor of preventive medicine at
the Keck School. (Photo/Don Milici)
The USC study also looked at new state of California policies intended to cut back on
vehicular greenhouse gas emissions that cause climate change. An important aim of these
policies is to reduce vehicular emissions of greenhouse gases, both by improving fuel
efficiency and reducing vehicle miles traveled by increasing use of public transportation.
As part of these policies, housing developers would be offered incentives, such as speeding
up environmental review, to design projects located closer to transit stops with bus or rail
service that will encourage use of fuel-efficient mass transit.
The investigators noted, however, that transit stops are often located on or near busy
roads and that there has been little study of the impact of these policies on exposure to
children living near major roadways.
The study concluded that better information is needed to develop the optimal mix of
policies that reduce sprawl, encourage walking and use of mass transit to reduce vehicle
miles traveled, greenhouse gases and regional air pollution, as well as to reduce childrenâ€™s
near-roadway exposure to emissions from vehicles still traveling on roadways.
â€œPlans to reduce greenhouse gas emissions and combat climate change offer an
opportunity to develop â€˜win-winâ€™ strategies that will maximize the health benefits from
reduction both of greenhouse gases and of air pollutants that directly harm children,â€
â€œThere is also emerging evidence that other diseases may be caused or exacerbated by
urban air pollution, including atherosclerosis, lung cancer, chronic obstructive pulmonary
disease and neurological disorders,â€ he added. â€œThus, policies to combat climate change
may have near-term health benefits beyond reducing the burden of disease due to
By using data from the Childrenâ€™s Health Study, a long-term study of effects of air
pollution ongoing since 1993, the researchers estimated the effects of air pollution on
children suffering from asthma.
Regional air pollution measurements from the U.S. Environmental Protection Agency and
area maps were used to estimate exposure to near-roadway pollution in the Los Angeles
area. This information was linked to population data.
Asthma exacerbation in this study was connected to regional pollutants, including
nitrogen dioxide and ozone that cover large parts of the air basin, and to near-roadway
pollutants that are responsible for the development of asthma.
The researchers found that living near busy roads contributed disproportionately to the
more serious exacerbations of asthma in children, including emergency room visits and
In addition, a 20 percent reduction in childrenâ€™s near-roadway pollution exposure would
result in an estimated 5,900 fewer cases of childhood asthma in Los Angeles County,
according to the research, whereas a 20 percent increase in exposure would result in 5,900
more cases of asthma.
Funding for the research was provided by funds from British Petroleum as part of an air
quality violations settlement agreement with the South Coast Air Quality Management
District, a California state agency.
The study also was supported by a National Institute of Health grant, as well as grants
from the Environmental Protection Agency and support from the Hastings Foundation.
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