Exposure to air pollution while sitting in traffic is associated with high blood pressure, according to a new study.
The "randomised crossover trial found the inhalation of traffic-related air pollution while in a car with unfiltered air was associated with a 4.5 mm Hg [millimetres of mercury] increase in blood pressure", said researchers from the University of Washington.
They analysed the blood pressure of 16 people, aged between 22 and 45, who were driven through traffic in the Washington city of Seattle for three days between 2014 and 2016.
On one of those days, the car was fitted with a particulate air filtration system. On the other two days, "on-road air was entrained into the vehicle", the researchers said.
They found changes in blood pressure among participants happened rapidly after a commute in an unfiltered vehicle. Blood pressure peaked within an hour of exposure and persisted throughout the next 24 hours, as reported in the Annals of Internal Medicine journal.
"Fourteen three-minute periods of blood pressure were recorded before, during and up to 24 hours after a drive," said the study. "At 1 hour, mean diastolic blood pressure, adjusted for pre-drive levels, order, and carryover, was 4.7 mm Hg higher... for unfiltered drives compared with filtered drives, and mean adjusted systolic blood pressure was 4.5 mm Hg higher.
"At 24 hours, adjusted mean diastolic blood pressure (unfiltered) was 3.8 mm Hg higher... and adjusted mean systolic blood pressure was 1.1 mm Hg higher."
The findings suggest traffic-related air pollution not only raised blood pressure but "the effects of air pollution on blood pressure may be reduced with effective cabin air filtration", the authors wrote.
More studies with higher sample sizes were needed to validate the findings, the research said.
"These are the size of effects from things like salt in the diet that are well-known to increase blood pressure," said lead author Joel Kaufman, from the University of Washington's Environmental & Occupational Health Sciences, Medicine and Epidemiology department. "Elevated blood pressures are risk factors for heart disease, stroke and kidney disease," he told Newsweek.
In Aotearoa, high blood pressure affects about one in five people, according to the Stroke Foundation NZ.
