Rush-Hour Drivers Are Breathing In Twice as Much Pollution As Previously Thought

Crawling along in rush-hour traffic with the AC on and windows up may give the impression of being at least somewhat insulated against the clouds of air pollution outside, but new research suggests that that not only is this an illusion, it may be a dangerous one as well. A recent study published in Atmospheric Environment by researchers at Duke University found that levels of both airborne particulate matter and damaging chemicals detected inside of cars are as much as twice that of what was previously assumed.

The reason for the disparity between what the Duke group measured and existing pollution data is pretty obvious. Most pollution measurements are taken outside. Sensors are typically placed alongside roadways then left to collect data continuously for 24 hours. Here, measurements were taken where drivers actually do most of their breathing: inside the car. Sampling devices were strapped into passenger seats and taken for rides through morning traffic in and around Atlanta.

The drives took place in a variety of conditions, including highway traffic and downtown congestion. Speeds were varied and measurements were taken with windows both up and down. In all cases, the pollution levels were higher than expected.

"There are a lot of reasons an in-car air sample would find higher levels of certain kinds of air pollution," Heidi Vreeland, first author of the new paper, offered in a statement. "The chemical composition of exhaust changes very quickly, even in the space of just a few feet. And morning sun heats the roadways, which causes an updraft that brings more pollution higher into the air."

The air samples collected in the study were considered with respect to oxidative stress. This can arise from both the presence of certain chemicals and fine particulate matter that gets suspended in the air. Cells in the body get hit with the wrong stuff and damaging reactions often result, such as inflammation and DNA damage. So, we're talking about cancer, heart disease, Alzheimer's, and all kinds of other bad stuff.

"My two cents is that this is really an urban planning failure," study co-author Roby Greenwald said. "In the case of Atlanta, the poor air quality on the highways is due to the fact that 6 million people live in the metro area, and most of them have little choice but to get into an automobile to go to work or school or the store or wherever. Auto-centric transportation plans do not scale well to cities of this size, and this is one more example of how traffic negatively affects your health."

Riding a bike in traffic can often feel like you're basically sucking on a tailpipe, so it'd be interesting to see this work duplicated with a sensor strapped to some bike messenger's handlebars. The new study would seem to imply that cyclists may be better off after all.