Rush-hour traffic air raises blood pressure, study finds

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A recent study published in the Annals of Internal Medicine has uncovered a significant health concern: exposure to unfiltered air during rush-hour traffic not only raises blood pressure during the journey but also maintains this increase for up to 24 hours afterward.

For a long time, the continuous flow of cars on busy roads has been a characteristic of American cities. This constant movement releases a mix of pollutants, including exhaust fumes, brake and tire wear, and road dust.

Research has linked long-term exposure to these traffic-related pollutants with a higher risk of cardiovascular diseases, asthma, lung cancer, and premature death.

Joel Kaufman, a professor at the University of Washington and the study’s lead author, explains that the human body has complex systems to regulate blood pressure, and traffic-related air pollution seems to disrupt these mechanisms.

Earlier, Kaufman’s lab had found that diesel exhaust fumes could increase blood pressure in controlled settings. This latest study aimed to replicate these findings in a real-world environment.

Healthy participants aged between 22 and 45 were driven through rush-hour traffic in Seattle while their blood pressure was monitored.

During some drives, unfiltered road air was allowed into the car, while in others, the car was equipped with HEPA filters that blocked 86% of particulate pollution. The participants were unaware of whether they were breathing filtered or unfiltered air.

The results were concerning: breathing unfiltered air led to a net increase in blood pressure of more than 4.50 mm Hg compared to drives with filtered air.

This increase was rapid, peaking about an hour into the drive and persisting for at least 24 hours. The study did not explore effects beyond this time frame.

The magnitude of this increase is similar to what one might expect from a high-sodium diet.

Kaufman notes that even modest increases in blood pressure, when viewed across a population, are linked to a significant rise in cardiovascular diseases.

This study adds to the understanding that air pollution, even at relatively low levels, can significantly impact heart health.

A key focus of the study was ultrafine particles, a pollutant less than 100 nanometers in diameter and largely unregulated.

These particles, abundant in traffic-related pollution, were effectively filtered out during the study, suggesting their potential role in affecting blood pressure. However, further research is needed to establish this conclusively.

This study is particularly relevant as traffic-related air pollution is a major contributor to air quality variation in US metropolitan areas.

Michael Young, a former postdoctoral fellow and the study’s lead author, highlights the significance of this research in replicating real-world conditions and separating the effects of pollution from other factors like stress and noise.

The research underscores the health risks posed by everyday exposure to traffic pollution and suggests the need for more robust air quality control measures in urban settings.

If you care about high blood pressure, please read studies about unhealthy habits that may increase high blood pressure risk, and drinking green tea could help lower blood pressure.

For more information about high blood pressure, please see recent studies about what to eat or to avoid for high blood pressure,  and 12 foods that lower blood pressure.

The research findings can be found in the Annals of Internal Medicine.

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