Traffic crawls through downtown Atlanta along Interstate 75/85 during rush hour, May 9, 2005 in Atlanta, Georgia.

(Barry Williams/Getty Images)

At a Glance

A new study has found twice as much pollution is present inside vehicles during rush hour.The measurements were taken inside cars during Atlanta's rush hour and studied a wide range of conditions.

Pollution expelled from thousands of vehicles during rush hour is even more dangerous to humans than previously believed, according to a new study.

The findings, from the Georgia Institute of Technology, Emory University andDuke University, came from the first-ever study of in-car measurements and concluded levels of some harmful particulate matter are twice as high as scientists believed before the data was collected. Previous pollution studies were performed by placing sensors on the side of the road, but when the devices were placed in the passenger seat of vehicles, they found the amount of particulate matter was twice as high.

"We found that people are likely getting a double whammy of exposure ," Michael Bergin, professor of civil and environmental engineering at Duke, said in an article that followed the study's release. "If these chemicals are as bad for people as many researchers believe, then commuters should seriously be rethinking their driving habits."

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Long-term exposure to pollution can lead to major health effects, including , according to Reuters. When the fine particulate matter, known as PM 2.5, gets into the lungs and bloodstream, the body overreacts and produces excess chemicals to fight it, which can destroy healthycells and DNA, the Duke University article also said.

With so many threats to the health of millions, researchers have an added incentive to learn more about just how much pollution is being ingested by rush-hour drivers on a daily basis.

The study was performed on a variety of Atlanta roads in a slew of different conditions. Some vehicles studied were on highways, while others were on side roads. In each of the 30 cars used during the 60 rush-hour test commutes, pollution levels were higher than previous studies had shown.

"There’s still a lot of debate about what types of pollution are cause for the biggest concern and what makes them so dangerous," said Bergin in the Duke University article. "But the bottom line is that driving during rush hour is even worse than we thought."