Idling emissions particularly harmful to children

Long-haul truck drivers have a tendency to keep their motors running for hours at a time – sometimes as an unintended consequence of laws meant to ensure proper rest for freight drivers.

Idle trucks are, to slightly alter a famous adage, ‘the devil's playthings’. Keeping the engine on at low speed is something millions of drivers do every day while waiting for parking spots or picking children up curbside. In the United States, long-haul truckers are particularly heavy idlers: from taking federally-required rest periods to sitting in line at border crossings, truckers spend a lot of time waiting—often leaving their rigs running.

Idling vehicles release greenhouse gases that are dangerous to humans.

The Environmental Protection Agency (EPA) estimates that in the United States, idling produces annual emissions of 11 million tons of carbon dioxide and 5,000 tons of particulate matter. The resulting damage to air quality particularly impacts sufferers of asthma, chronic obstructive pulmonary disease, cardiovascular disease, cancer, and diabetes. According to a 2006 publication by the non-profit group Environment and Human Health, Inc. (EHHI), in areas with high air pollution, mortality rates among at-risk groups dramatically increase.

Because of both their frequent proximity to diesel exhaust-spewing school buses and their young pulmonary systems, children are particularly susceptible to vehicle emissions. Diesel particulate matter, which the EPA recognizes as a possible carcinogenic, falls into the PM2.5 category, meaning its diameter is smaller than 2.5 millimeters. Because of its small size, it easily penetrates the narrower airways of children and buries itself deep within the lungs, where it is likely to be retained.

Today, 3.5 million U.S. children—many of them from low-income sectors--live in areas exceeding government particulate standards. The results are dire. In a seminal study, Boston-based Alternatives for Community and Environment (ACE), an environmental justice organization, found that in the Dudley Square section of Roxbury—likemany poor communities, home to transportation depots and shipping depots, where idling is constant—asthma rates were more than twice as high as elsewhere in Boston; for children living in Roxbury and other low-income areas, the likelihood of developing asthma was 7.6 times that of kids from wealthy neighborhoods.

While casual observers often view traffic to be the main culprit in emissions, idling vehicles are in fact bigger polluters. A 2007 EPA study indicated that concentrations of PM2.5 measured at a truck stop near a highway interchange were highest at night—a finding that suggests that emissions were deriving primarily from idling truck engines, rather than from busier daytime traffic. Similarly, EHHI testing determined that idling school buses had higher concentrations of particulates and carbon than moving buses.

Scientists stress that the effects of fine particulate matter like that contained in diesel exhaust are still not fully known. "Neurological disease is a big outcome that we don't yet understand," said John Froines, a retired UCLA professor and director of the Southern California Particle Center, in a July 2012 article in the Contra Costa Times. Froines said ultrafine particles, some the size of a virus, can go straight to the brain through the nasal passages and along nerves, rather via the lungs. "There has to be a focus on ultra fines," he said, "and it hasn't happened."