Is pollution turning us into couch potatoes?

There are lots of reasons why people don’t exercise: lack of time, addiction to screens, or pure laziness. But scientists have found one more factor that may be keeping us glued to our couches. According to a new study in PLOS ONE, higher levels of air pollution are linked to decreased exercise.

Sedentary behavior is a major health issue. It’s associated with heart disease, diabetes, and other maladies. But researchers haven’t looked deeply into the question of whether environmental factors, such as pollution, contribute to lack of physical activity.

The researchers studied air quality measurements taken in 2011 by the U.S. Environmental Protection Agency, which monitors thousands of locations across the country. They also analyzed data from a 2011 survey of Americans’ leisure activities. Participants were asked whether they had performed any physical activity outside their job, such as running or golf, in the past month.

Of the 329,628 survey participants included in the study, about a quarter said they had not exercised in their free time at all that month. Black and Hispanic people were the most sedentary; people were also more likely to be inactive if they were divorced, widowed, less educated, or earned less than $50,000 a year. Respondents in the West exercised the most, and those in the Southeast the least.

Exposure to a pollutant type called PM2.5 — meaning particulate matter less than 2.5 micrometers wide — was divided into five levels, ranging from low to high. Compared to people living in areas with the lowest PM2.5 exposure level, residents of normal weight in higher-exposure areas were 16 to 35 percent more likely to be inactive, the team reports. The researchers controlled for other factors such as age, income, ethnicity, asthma, disability, and smoking.

Why would pollution keep people from exercising? It might be because poor air quality makes it harder to breathe. But perhaps people also know that inhaling smoggy air isn’t good for their health, so they’re more likely to stay indoors. Roberta Kwok | 11 March 2014

Source: Roberts, J.D., J.D. Voss, and B. Knight. 2014. The association of ambient air pollution and physical inactivity in the United States. PLOS ONE doi: 10.1371/journal.pone.0090143.

Image © Dean Drobot | Shutterstock