Exercising regularly can lower the risk of high blood pressure, even if people live in areas where air pollution is relatively high, according to recent research.
The research was published in the American Heart Association's flagship journal Circulation.
The risk-benefit relationship between air pollution and physical activity is an important public concern because more than 91 percent of people worldwide live in areas where air quality does not meet World Health Organization (WHO) guidelines.
Researchers studied more than 140,000 non-hypertensive adults in Taiwan and followed them for an average of 5 years.
Researchers classified the weekly physical activity levels of each adult as inactive, moderately active, or highly active.
Researchers also classified level of exposure to fine particulate matter (PM2.5) as low, moderate and high.
PM2.5 is the most commonly used indicator of air pollution.
High blood pressure was defined as 140/90 mm Hg.
Overall, people who are highly active and exposed to low levels of pollution had a lower risk of developing high blood pressure.
People who were inactive and exposed to highly polluted air had a higher high blood pressure risk.
Each increase in PM2.5 level was associated with a 38 percent increase in risk of incident hypertension, whereas each increase in physical activity level lead to a 6 percent lower risk of hypertension.
This suggests that reducing air pollution is more effective in preventing high blood pressure.
The benefits of regular physical activity held up regardless of pollution level.
People who exercised moderately had a 4 percent lower risk of high blood pressure than those who didn't exercise.