Exercising in polluted areas still protective against hypertension

Regular physical activity (PA) yields substantial protection against high blood pressure despite exposure to relatively high levels of air pollution, a study has found.

The study included 140,072 hypertension-free adults (mean age, 41.7 years; 48.8 percent male) in Taiwan, where the annual PM_2.5 concentrations exceed the limit recommended by the World Health Organization (WHO). All participants underwent standard medical screenings over a mean follow-up of 5.01 years. In total, 16,077 participants developed hypertension, with an incidence rate of 2.3 per 100 person-years.

Approximately 34.2 percent of the entire population were physically inactive (0 metabolic equivalence values-hours), and 69.0 percent had a mostly sedentary occupation. On the other hand, 29.8 percent of patients had moderate PA (median, 3.75 metabolic equivalence values-hours), and 36.0 percent had high PA (median, 15.7 metabolic equivalence values-hours).

Overall, the mean PM_2.5 exposure was 26.1 µg/m³, with exposures generally comparable among patients across different PA levels. The prevalence rates of cardiovascular disease, diabetes mellitus, and cancer were 2.1 percent, 2.9 percent, and 1.5 percent, respectively.

In multivariable Cox regression models, higher PA levels vs inactivity were associated with about an 8-percent lower risk of hypertension (moderate PA: hazard ratio [HR], 0.93, 95 percent confidence interval [CI], 0.89–0.97; high-PA: HR, 0.92, 95 percent CI, 0.88–0.96).

Conversely, higher vs low PM_2.5 exposure levels posed an increased hazard of hypertension (moderate exposure: HR, 1.37, 95 percent CI, 1.32–1.43; high exposure: HR, 1.92, 95 percent CI, 1.81–2.04). There was no significant interaction seen between PA and PM_2.5 (HR, 1.01, 95 percent CI, 1.00–1.02).

The present data suggest that PA may be a suitable hypertension prevention strategy among people residing in relatively polluted regions, according to the researchers.