Study Shows How Air Pollution and Weather Influence Daily Physical Activity in People with COPD

People with chronic obstructive pulmonary disease (COPD) have low levels of physical activity. However, there is little scientific evidence on how environmental factors affect their physical activity in the short term. A study led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Foundation, investigated the effects of air pollution and weather conditions on daily physical activity levels in people with COPD.

The study, conducted over two 7-day periods separated by one year, involved 408 people with COPD in Catalonia, 85% of whom were men. The research team analysed the relationship between air pollution, mean and maximum temperature and rainfall with the amount and intensity of daily physical activity. Levels of air pollutants, including nitrogen dioxide (NO2), PM10 and PM2.5 particles, were estimated up to five days before each assessment.

The results of the study showed that air pollution was associated with a significant decrease in physical activity up to four days after exposure to particulate matter. Pollution had a greater impact on people with severe COPD and those with higher levels of regular physical activity. In contrast, higher temperatures and less precipitation were associated with an increase in the amount of physical activity on the same day, as well as a decrease in sedentary time.

Contrary to the research team's hypothesis, there was no threshold for ambient temperature above which a negative effect on physical activity levels would be expected. This may be explained by the lack of data collected during the hottest months of the year. "Future studies should include measures of physical activity during the hottest period of the year to determine whether a temperature threshold really exists, especially in the context of climate change and in anticipation of more frequent, extreme and longer-lasting, heat waves," says Judith Garcia-Aymerich, ISGlobal researcher and senior author of the study.

Clinical and public health implications

This is the first study to show that exposure to levels of air pollution, even below current World Health Organisation recommendations, can lead to a reduction in the amount and intensity of physical activity in people with COPD. The findings have important implications for formulating treatment strategies to ensure the health and well-being of people with COPD.

"Our findings provide evidence that air pollution and climatic factors must be considered when making physical activity recommendations or when assessing physical activity outcomes in people with COPD. The impact of these factors on people's health needs to be considered when planning and redesigning cities," says Alícia Josa-Culleré, ISGlobal researcher and first author of the study.

"Regular physical activity is a key pillar in the treatment and rehabilitation of COPD. Daily physical activity routines depend on daily decisions, so it is important to identify the factors that influence these choices. Our findings suggest that air pollution and weather factors play an important role when deciding whether to engage or not in physical activity," adds Garcia-Aymerich.