People who continue with their regular physical activities may have reduced the risk of first and recurrent heart attack even in the areas with moderate-to-high levels of traffic pollution, a new study suggests. The findings suggest that higher levels of nitrogen dioxide (NO2) — a pollutant generated by traffic — were associated with more heart attacks, but the risk was lower among those who were physically active. “Our study shows that physical activity even during exposure to air pollution, in cities with levels similar to those in Copenhagen, can reduce the risk of heart attack,” said lead author Nadine Kubesch from the University of Copenhagen.
For the study, published in Journal of the American Heart Association, the researchers in Denmark, Germany, and Spain evaluated outdoor physical activity levels (sports, cycling, walking, and gardening) and NO2 exposure in 51,868 adults aged between 50-65 years.
The researchers also compared self-reported activities and lifestyle factors against heart attack and to estimate average NO2 exposure, they used national traffic pollution monitoring data for each participants’ address.
They found that moderate cycling for four or more hours per week cut risk for recurrent heart attack by 31 percent and there was a 58 percent reduction when all four types of physical activity (together totaling four hours per week or more) were combined, regardless of air quality.
Those who participated in sports had a 15 percent lower rate of initial heart attacks and there was a nine percent risk reduction associated with cycling, the researchers said.
Compared to participants with low residential NO2 exposure, those in higher risk areas had a 17 percent increase risk in first heart attack and 39 percent for recurrent heart attack, they added.