2010 Feb. 1: WI Milwaukee: Particulate air pollution faced by bicyclists
Drivers (and sometimes cyclists too) face health sapping air pollution on the roads
May 1, 6:24 AMBicycle Transportation ExaminerAdam Voiland
Air pollution threatens drivers as well as cyclists. (Credit: Biofriendly)
The American Lung Association released its annual State of the Air report this week, and the findings are sobering. More than six in ten American residents—more than 186 million people—live in areas with dangerous levels of air pollution. Although the situation has improved somewhat in the Washington DC metro area throughout the last decade, both ozone and particulate pollution remain major killers.
The District faced an average of 55 orange alert days and two red alert days between 2005 and 2007 caused by high ozone levels, the report found. A decade ago, ozone pollution levels were significantly worse in DC, as this trend chart from last year’s State of the Air report shows. Still, the report gives DC an "F" on ozone pollution, and the city ranked 14th highest in the nation.
Ozone, a gas poisonous to humans produced mainly by automobile emissions, causes inflammation of the lungs and threatens people of all ages with problems that include premature death, chest pain, asthma, wheezing, and increased susceptibility to respiratory infections.
Levels of particulate pollution, which can trigger heart problems, were somewhat better. During the study period, DC faced an average 21 orange alerts days and 1 red alert day each year due to short-term particulate pollution. Though that was enough to keep DC out of the list of top 25 most polluted cities, it still left the District with a failing grade. Some of the counties with the least particulate pollution, in contrast, were found in Maine, Montana, South Dakota, and Wyoming.
There’s a long-running medical debate about whether drivers, cyclists, or pedestrians face the greatest risks on the roadways as a result of air pollution. If you’re tenacious with Google and Pubmed, you can find seemingly reliable research that comes to a variety of different conclusions (here, here, here, here, and here are just a few examples), so it’s unlikely that any particular mode of transportation faces overwhelming risks in comparison to the others.
Why the discrepancies between studies? Some look specifically at ozone, others at particulate matter, and others at volatile organic compounds. And while some, for example, looked at moving cars, others looked at stationary cars. Finally, the capabilities of the instruments researchers use to measure the air–and the conditions during which they measure–varies considerably with the study.
One thing, however, is quite clear. The notion that many drivers have of being hermetically sealed away and protected from air pollution in the cabin of their car is false. In fact, car drivers sit in the middle of a continually replenishing stream of air pollution.
There are a couple studies, in particular, that are worth noting. In 2001, a Danish researcher showed that the concentrations of the harmful volatile organic compounds xylene, toluene, and ethylbenzene were far higher in the cabin of a car than in a cyclist’s breathing zone. A study published by Harvard School of Public Health researchers came to a similar conclusion (see page 17 of this report for the data).
It’s also well-known that dangerous fine and ultrafine particulate pollution can easily infiltrate the interior of a car, even though car air conditioning systems can filter out some of the larger, less-dangerous particulates. In 2000, the International Center for Technology Assessment published a thorough report that explores the effect that a whole range of different pollutants have on the health of drivers.
Though some studies suggest that cyclists face less exposure to particular pollutants than others, cyclists certainly don’t get off scot-free. Some research–somewhat predictably–has shown that exercising heavily in polluted air increases a person’s exposure to pollution.
Still, for any one person, there’s little doubt in my mind that the health benefits of cycling, even in polluted air, far outweigh the risks of air pollution. That does little, however, to temper my frustration with transportation policies that have failed to reduced congestion levels to safer and more appropriate levels for all us of–drivers and cyclists included.