New research by the Harvard Center for Risk Analysis (HCRA) at the School of Public Health estimates that the additional fine particulate matter emissions that can be traced back to traffic congestion in the nation's 83 largest urban areas led to more than 2,200 premature deaths in the U.S. last year. The related public health cost, researchers say, was, conservatively, at least $18 billion.

The study, "The Public Health Costs of Traffic Congestion: A Health Risk Assessment," was published in the scientific journal Environmental Health. It is the first to attempt to quantify the public health implications of growing traffic congestion in America.

As might be expected, the public health toll of traffic congestion was estimated to be highest in some of the nation's largest urban areas. The Los Angeles/Long Beach/Santa Ana, Calif., area was first, with an estimated additional 426 premature deaths and $3.3 billion in public health costs. It was followed by: New York City/Newark, N.J. (337 premature deaths, $2.6 billion in costs); Chicago/Northern Indiana (251 premature deaths, $2 billion costs); and San Francisco/Oakland, Calif. (124 premature deaths, $1 billion in costs).

In conducting the study, the Harvard researchers projected the estimated growth of traffic congestion-and resulting emissions-from the baseline year 2000 through 2030 if no additional transportation infrastructure capacity is provided in the 83 urban areas to accommodate projected population growth.

They forecast traffic congestion will rise more than 30 percent over the period 2000 to 2030 in 18 urban areas.

While the study was not designed to address traffic congestion-reducing strategies, researchers said solutions would likely vary from community to community. Potential strategies range from better traffic management through congestion pricing, traffic light synchronization and more efficient response to traffic incidents to adding new highway and public transit capacity. More refined models of traffic dynamics specific to each urban area linked to the public health models developed in the study could be used to explore the impacts of proposed strategies.

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