Your Car Is Slowly Killing You

A new study shows that drivers are exposed to high levels of pollution when stopped at traffic lights. Here are strategies for reducing the risk.

(Photo: Zoran Milich/Getty Images)

Feb 24, 2015· 2 MIN READ
David Kirby has been a professional journalist for 25 years. His third book, Death at Seaworld, was published in 2012.

You’re not just wasting time stuck in traffic and at stoplights—you may also be taking years off your life.

A new study in the journal Atmospheric Environment reported that when drivers stop at red lights, they are exposed to microscopic pollution particles at levels 29 times higher than while their car is in motion. Exposures are even higher when cars are close together or at intersections surrounded by tall buildings. Those particles can cause respiratory and heart disease.

“Where drivers spend just 2 percent of their journey time passing through traffic intersections managed by lights, this short duration contributes to about 25 percent of total exposure to these harmful particles,” the researchers said.

The scientists equipped a car with sensors and took pollution readings inside and outside the vehicle under a variety of conditions.

The study was conducted in the United Kingdom, but its findings are applicable to other countries, according to coauthor Prashant Kumar of the University of Surrey.

“The basics remain the same,” Kumar said in an email. “Stringent emission standards and cleaner fuel types help reduce emissions, but traffic intersections will still remain pollution hot spots.”

Drivers stuck in rush-hour traffic also inhale higher levels of particulate matter.

Emissions outside stopped cars are much higher than those inside, posing increased risks for pedestrians and cyclists at intersections, the report said.

How does pollution get inside your car? Through open windows and ventilation systems.

“When we closed the windows and switched off the fan, this gave us the lowest exposure,” Kumar said. “When the windows were closed but the fan was on, the exposure was at its highest. Switching on the fan sucks the dirty air from outside to inside the vehicle, and the air inside takes some time to dilute or escape.”

Robert Sinclair, spokesperson for the American Automobile Association, said in an email that nearly all contemporary cars have cabin filters “that are supposed to substantially reduce any serious airborne pollutants, especially allergens. But, it’s vitally important that the filters be changed according to the vehicle maker’s maintenance schedule.”

To reduce interior pollution, drivers should use the recirculation feature in the climate system during urban travel.

Idling engines are not just dangerous but wasteful. A 2008 study found that stopped cars consume an additional 10 billion gallons of gasoline each year in the United States.

“A driving commuter in the average American big city wastes an average of 52 hours a year sitting in traffic while sending enough CO2 into the air to fill up the Louisiana Superdome four times,” Sinclair said.

There are ways to reduce exposure to such pollutants.

“Keep windows shut, fans off and try to increase the distance between you and the car in front where possible,” Kumar said. “Pedestrians could perhaps consider changing routes.”

Sinclair said the AAA endorses synchronized stoplights and intersection overpasses to allow for greater traffic flow. He added that traffic planners should build bypasses around congested urban areas, expand street and highway capacity, and construct car-only and truck-only lanes.

Other solutions include mass transit, electric and hybrid cars, and “stop-start” devices that shut off engines while vehicles are stopped. That technology can improve fuel efficiency as much as 15 percent in stop-and-go traffic, according to The Detroit News.

The paper reported that only 7 percent of U.S. cars have stop-start devices, compared with 60 to 70 percent of European vehicles.

Sinclair said the technology is promising but not without its problems. “Some systems are too slow restarting the engine, making for dangerous left turns across oncoming traffic,” he said.

“Most systems can be deactivated, thereby losing any benefit they provide,” he added. “It’s a work in progress.”