Heavy Traffic

This week, the Washington Post reports the results of a recent survey showing that area residents spend far longer getting to work and find themselves in daily traffic jams three times as often as commuters elsewhere. The median commute time to work is 30 minutes each way. However,

[i]n spite of increasingly long and frustrating commutes, the survey found that Washingtonians remain addicted to their cars. Three in four area commuters drive to work alone. Carpooling is no more prevalent here than it is elsewhere in the country. Metro is widely admired but largely bypassed, a boutique transportation system that serves a hard-core constituency but is viewed by most commuters as inconvenient.

Though the DC transportation system borders on collapse, according to local officials, people seem determine to continue to rely on their cars.

Government officials said they have all but given up on attempts to do anything extraordinary to solve area transportation problems. Instead, they are trying to broaden commuting options for people by experimenting with such proposals as allowing drivers without passengers to pay to use carpool lanes. But they said there was little they can do if people continue to live farther and farther from their jobs.

Beyond the impact to quality of life and the threat to energy security, there may be an environmental health cost from over-reliance on automobiles.

The air quality impacts principally associated with motor vehicles are emissions of hazardous air pollutants and reactive organic compounds. The hazardous air pollutants include known and probable human carcinogens (benzene, formaldehyde, 1,3-butadiene, diesel exhaust particulates) and respiratory irritants (formaldehyde, acetaldehyde and acrolein). More resources on HAPs from mobile sources can be found here. The reactive organic compounds along with oxides of nitrogen and ultraviolet light result in the formation of the respiratory irritant ozone.

The numerous epidemiological studies provide conflicting evidence about human cancer risks associated with the carcinogens emitted from motor vehicle emissions. An example of one study showing an association between childhood leukemia and traffic density is here; an example of one study finding no association is here.

There may be a question as to whether or not to worry about cancer risks from car and truck exhaust, but what is clearer is the linkage between vehicle emissions and ozone, and ozone and respiratory health. According to an EPA fact sheet, inhaling low levels of ozone can cause acute respiratory problems, aggravate asthma significantly reduce lung capacity, produce inflammation of lung tissue, lead to hospital admissions and emergency room visits (10 to 20 percent of all summertime respiratory-related hospital visits in the northeastern U.S. are associated with ozone exposures), and impair the body's immune system defenses, making people more susceptible to respiratory illnesses, including bronchitis and pneumonia. Up to 40 percent of the U.S. population may be at an increased respiratory risk from ozone (with a nod to Brooklyn Dodger for pointing me to the Yale and Johns Hopkins study). Many of the drivers, who live far from where the emissions are highest, don’t have to bear the costs associated with these problems.

The counties around Washington D.C. are non-attainment for ozone, meaning that concentrations of ozone in air are higher than the National Ambient Air Quality Standards. Emissions from the vehicles are a big part of that problem. With the transportation system nearing collapse, meaning more traffic jams, more time spent idling and more emissions, ozone impacts could be expected to worsen.

Driving less would help. A 1996 study published in Journal of the American Medical Association reported on traffic reduction strategies implemented in Atlanta during the Summer Olympics and the resulting health outcomes. The conclusion from the study was that efforts to reduce downtown traffic congestion in Atlanta during the Olympic Games resulted in decreased traffic density, a corresponding reduction in ozone and significantly lower rates of childhood asthma events. The Metro might be inconvenient, but so is asthma.