Unfiltered traffic-related air pollution linked to increased BP

Key takeaways:

• Mean diastolic and systolic BP were higher after 1 hour of riding in cars with unfiltered air vs. filtered air.
• Filtration systems may mitigate pollution’s impact on vascular health.

Inhalation of traffic-related air pollution in a car with unfiltered air was linked to a rapid increase in BP, which peaked within 1 hour, a recent study found.

According to Michael T. Young, MPH, PhD, from the department of environmental and occupational sciences at the University of Washington, and colleagues, “[traffic-related air pollution (TRAP)] exposure is recognized as a risk factor for cardiovascular disease and other health effects.”

TRAP is an air pollution mixture made up of roadway sources like brake and tire wear or vehicle exhaust, the researchers explained.

“It has been proposed that the relationship between air pollution exposure and cardiovascular disease is mediated through inflammation and autonomic dysregulation,” they wrote in Annals of Internal Medicine.

Young and colleagues noted there is a lack of information on in-vehicle TRAP exposure and related cardiovascular changes, despite possible health risks and increasing commute times. According to the U.S. Department of Energy, the average commute time to work was around 27 minutes in 2021, up from 25.2 minutes in 2010.

The researchers analyzed data on 16 individuals aged 22 to 45 years who went on a 2-hour car ride in a vehicle with unfiltered air for 2 days and a vehicle equipped with high-efficiency particulate air filtration on another day. For each drive, the participants’ BP levels were recorded 14 times during 3-minute periods: once immediately before the drive; nine times during the drive; three times after the drive on the same day; and one time 24 hours after the drive.

Among 13 participants with complete data, Young and colleagues reported that the adjusted mean diastolic BP was 4.7 mm Hg (95% CI, 0.9-8.4) higher for unfiltered drives at 1 hour vs. filtered drives, whereas mean systolic BP was 4.5 mm Hg (95% CI, –1.2 to 10.2) higher.

At 24 hours, the adjusted mean diastolic BP and mean systolic BP were 3.8 mm Hg (95% CI, 0.02-7.5 mm Hg) and 1.1 mm Hg (CI, –4.6 to 6.8 mm Hg) higher during unfiltered drives compared with filtered drives.

Although the results show that TRAP does raise BP, the researchers noted that the “estimates were imprecise and the CIs for the increases included zero at various time points.”

Young and colleagues added that their findings “suggest the potential for particle filtration to mitigate the acute effects of air pollution exposure and justify further research into the effects of filtration in other acute and long-term exposure settings.”

“The clinical implications of transient changes in blood pressure are not well understood, and further research is also needed to determine whether these changes might contribute to acute risk for cardiovascular disease events or long-term vascular alterations,” they concluded.

References:

• Average travel time to work. https://www.energy.gov/eere/vehicles/articles/fotw-1284-april-3-2023-average-travel-time-work-was-about-27-minutes-2021. Published April 3, 2023. Accessed Nov. 28, 2023.
• Young M, et al. Ann Intern Med. 2023;doi:10.7326/M23-1309.