Traffic Jams Trigger a 24-Hour Blood Pressure Surge

Creeping along in heavy traffic on a highway, especially when headed to an appointment or, worse, the airport, can elevate anyone’s blood pressure (BP). However, scientists have discovered that this BP surge occurs irrespective of external stressors and may be attributed to the low-quality air entering the car from surrounding traffic.

Conducting a randomized crossover trial, researchers at the University of Washington (UW) were astonished to find a connection between sitting in traffic and inhaling unfiltered air, leading to a 4.5 mm Hg increase in blood pressure. This increase peaked at approximately 60 minutes of exposure but persisted for up to 24 hours afterward.

“The body employs a intricate set of systems to maintain consistent blood pressure to the brain,” explained lead researcher Joel Kaufman, a physician and professor at UW. “It’s a highly intricate and tightly regulated system, and it seems that somewhere, within one of those mechanisms, traffic-related air pollution disrupts blood pressure.”

Controlled Experiments on Commuting Blood Pressure Impact

In the research, 16 participants aged 22-45 were chauffeured as passengers through peak-hour traffic in Seattle over three days to assess the impact of traffic pollution on blood pressure. For two days, the vehicle’s air circulation functioned normally to replicate typical driving conditions, while on another day, the car was equipped with a high-efficiency particulate air (HEPA) filter, blocking 86% of particulate pollution.

Blood pressure measurements were collected a day before, during, and after the drive, encompassing 14 three-minute tests. Image-based central retinal arteriolar equivalents (CRAEs) were measured before and after, along with assessments of brachial artery diameter and gene expression.

The average adjusted systolic blood pressure reading, elevated by 4.5 mm Hg compared to the baseline, is akin to the impact of a high-sodium diet.

“We are aware that modest increases in blood pressure like this, when observed at a population level, correlate with a significant rise in cardiovascular disease,” Kaufman emphasized. “There is a growing understanding that air pollution contributes to heart problems. The revelation that roadway air pollution, even at relatively low levels, can exert such a substantial influence on blood pressure is a crucial element in the puzzle we are working to unravel.”

Insights into Traffic-Related Air Pollution (TRAP) and Ultrafine Particle Filtration

Traffic-related air pollution (TRAP) stands as the primary contributor to air quality variations in U.S. metropolitan areas. TRAP is characterized by elevated levels of ultrafine particles, each measuring less than 100 nanometers in diameter, and these particles have frequently been linked to various adverse health outcomes related to air quality. In this context, the ultrafine particle concentration was minimal, equivalent to an Air Quality Index of 36 (a score below 100 is deemed satisfactory). Nonetheless, the filters effectively eliminated nearly all traces before entering the car.

“Ultrafine particles, the pollutant most efficiently filtered in our experiment—where levels are notably high on the road and low in the filtered environment,” Kaufman explained. “Hence, there’s an indication that ultrafines may have particular significance [for blood pressure]. Substantiating this requires further investigation, but this study offers a strong hint about the potential impact.”

Although the specific mechanism in TRAP triggering blood pressure changes is not yet fully understood, the researchers took precautions to eliminate other potential confounding factors.

“Studies on this topic often struggle to distinguish the effects of pollution from other roadway exposures like stress and noise, but with our approach, the sole distinction between drive days was air pollution concentration,” noted lead author Michael Young, a former UW postdoctoral fellow in the Department of Environmental and Occupational Health Sciences. “The findings are valuable because they can replicate situations that millions of people actually experience every day.”

Read the original article on: New Atlas

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