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In-Car Pollution Worse Than Feared

Sampling devices on passenger seats detected up to twice as much particulate matter as the roadside sensors.
Sampling devices on passenger seats detected up to twice as much particulate matter as the roadside sensors.

The first in-car measurements of exposure to pollutants that cause oxidative stress during rush hour commutes have turned up potentially alarming results. The levels of some forms of harmful particulate matter inside car cabins was found to be twice as high as previously believed.

Most traffic pollution sensors are placed on the ground alongside the road and take continuous samples for a 24-hour period. Exhaust composition, however, changes rapidly enough for drivers to experience different conditions inside their vehicles than these roadside sensors. Long-term sampling also misses nuanced variabilities caused by road congestion and environmental conditions, Science Daily reported.

To explore what drivers are actually exposed to during rush hour, researchers from Duke University, Emory University and the Georgia Institute of Technology strapped specially designed sampling devices into the passenger seats of cars during morning rush hour commutes in downtown Atlanta.

The devices detected up to twice as much particulate matter as the roadside sensors. The team also found that the pollution contained twice the amount of chemicals that cause oxidative stress, which is thought to be involved in the development of many diseases including respiratory and heart disease, cancer, and some types of neurodegenerative diseases.

The results were published on June 27 in the journal Atmospheric Environment.

“We found that people are likely getting a double whammy of exposure in terms of health during rush-hour commutes,” said Michael Bergin, professor of civil and environmental engineering at Duke. “If these chemicals are as bad for people as many researchers believe, then commuters should seriously be rethinking their driving habits.”

For the experiment, Roby Greenwald, a research assistant professor at Emory at the time, built a sampling device that draws in air at a similar rate to human lungs to provide detectable levels of pollution. The device was then secured to the passenger seats of more than 30 different cars as they completed more than 60 rush hour commutes.

Some drivers took highway routes while others stuck to busy thoroughfares in downtown Atlanta. While other details like speed and having windows rolled down varied, all of the sampling found more risk in air exposure than previous studies conducted with roadside sampling devices. “There are a lot of reasons an in-car air sample would find higher levels of certain kinds of air pollution,” said Heidi Vreeland, a doctoral student in Bergin’s lab and first author of the paper. “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.”

“My two cents opinion is that this is really an urban planning failure,” said Greenwald. “Auto-centric transportation plans do not scale well to large cities, and this is one more example of how traffic negatively affects your health.”

 

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