This is an excerpt from “Bikenomics: How Bicycling Can Save the Economy,” by Elly Blue (Microcosm Publishing, December 1, 2013, bikenomics.com). See our interview with Elly from spring 2013.
Car exhaust is no laughing matter. Nearly half of residents in major urban areas in North America live close enough to highways and other large roads to experience serious problems as a result. Exposure to car emissions worsens and may cause asthma and other lung conditions, including lung cancer. There is evidence to suggest that it leads to hardening of the arteries and thence to heart disease. One study has found an increased risk of heart attacks while in traffic, either while driving or using public transportation. Breathing car exhaust may increase the risk of developing diabetes; it is certain, however, that people who have diabetes suffer disproportionately from the effects of air pollution.
The worst effects of breathing polluted air are experienced where it is densest: in traffic. Spending time on and near highways, freeways, and other busy roads is terrible for your health. How near is a question that is still being studied, but researchers believe that the effects are worst within either a fifth or a third of a mile. People in cars or buses are exposed to considerably more air pollution, perhaps because of, rather than despite, being in a closed space. People walking and bicycling on or next to roads breathe more air, but inhale somewhat less pollution; and cyclists have been found to have even less risk if they are on paths that are separated from the road.
The burdens that come with air pollution are, as with so much else, not evenly distributed. Poverty and ethnicity are both major factors that determine the amount of car exhaust we breathe. Housing near a source of pollution, such as a freeway, busy road, or industrial site is generally where people with low incomes are able to live.
Children are particularly at risk, beginning before birth. Air pollution affects prenatal development, and a recent study suggests that exposure to air pollution such as diesel particulates, mercury, and lead may put a child at risk for autism. A separate study found double the rate of autism among children who live within 1,000 feet of a freeway in several major cities. Air pollution has also been linked, tentatively, to hyperactivity in kids and childhood cancers. And kids who have high daily exposure to car exhaust score lower on intelligence tests and have more depression, anxiety, and attention problems. This isn’t just a matter of where children live – one in three public schools in the U.S. are within a quarter mile of a highway, well within the danger zone.
Traffic jams and air pollution are often talked about at once, as though one inevitably causes the other, and that by fixing one you can also solve the other.
It doesn’t quite work that way.