Not only might traffic jams prompt frustration or anger among drivers or passengers, but exhaust-tainted air seeping into the cabin also pushes up blood pressure, according to the University of Washington.
"Inhalation of traffic-related air pollution while in a car with unfiltered air was associated with a 4.5 mm Hg [mercury] increase in blood pressure," the Seattle-based researchers found.
"This change in blood pressure occurred rapidly, peaked within 60 minutes of exposure, and persisted over 24 hours," they pointed out, in a paper published in the journal Annals of Internal Medicine.
For people who have no choice but to commute to work by road, air filters do help keep blood pressure down even when driving through traffic pollution, the study's authors said.
Drivers and passengers sitting in cars without good filtration underwent "significant net increases in blood pressure compared with drives with in-vehicle filtration," the researchers reported, showing that "the effects of air pollution on blood pressure may be reduced with effective cabin air filtration."
Air pollution - taking in that caused by factories, forest fires and other factors as well as traffic - was recently blamed for reduced life expectancy in several Asian countries by the University of Chicago.
Chinese research published this year by The Lancet, a British medical journal, suggested a link between air pollution and the growing problem of antibiotic resistance. Noise pollution from cars is meanwhile proven to cause cardiovascular and mental health problems.