Motor vehicle pollution a major contributor to American deaths

By Chris McCahill

Last year, following six years of decline, the number of traffic fatalities in the U.S. rose 5 percent—to 34,000—continuing the position of motor vehicle crashes as one of the leading causes of death, particularly among young people. It is the top cause of death for ages 5 to 24. Two recent independent studies now suggest that simply living near major roadways and breathing harmful emissions from motor vehicles might be an even greater threat to U.S. health, making the death toll from traffic far worse.

A new study from MIT concluded that vehicle emissions contributed to 53,000 premature deaths in 2005 (12 years premature, on average), exceeding the number of traffic fatalities by 30 percent and bringing the total deaths from traffic causes close to 100,000 annually. The researchers modeled emissions of fine particulate matter and other criteria pollutants from various sources, including power plants, industrial uses, and road transportation. They compared the output from those models to population densities to determine exposure rates and health impacts.

Their research validated similar previous studies, but offered a more detailed picture of nationwide emissions. Overall, fine particulate emissions pose the greatest health risk. Although motor vehicles account for only 7 percent of those emissions, they affect the greatest number of people because they are concentrated primarily in large metropolitan areas. Electric power generation, which has the second largest impact, is typically more isolated.

While the MIT study highlights major metropolitan areas where emissions pose a serious risk, an unrelated study from the University of New Mexico reveals the impacts are actually more widespread. By analyzing census data, Professor Gregory Rowangould found that roughly one-fifth of the U.S. population lives close enough to major roadways to be exposed to harmful emissions, including those in less urbanized areas. As he explained to the Los Angeles Times, this means there is potential for air quality violations in areas that aren’t currently being monitored. The study also shows that non-white and low-income households are affected at higher rates in all regions.

Chris McCahill is a Senior Associate at SSTI.