Study finds link between long-term exposure to air pollution and emphysema

Long-term exposure to air pollution was linked to increases in emphysema between 2000 and 2018, according to a new study funded by the National Institute of Environmental Health Sciences (NIEHS) and the National Heart, Lung, and Blood Institute (NHLBI), both part of the National Institutes of Health. The study was published in the Journal of the American Medical Association.

Emphysema, usually associated with smokers, is a chronic disease in which lung tissue is destroyed and unable to effectively transfer oxygen in the body, according to James Kiley, PhD, NHLBI's director of the Division of Lung Diseases.

“"These findings may offer one explanation for why emphysema is found in some people who never smoked,” said Kiley. “"The study's results, duration, and timing offer insight into the long-term effects of air pollution on the U.S. population."

The relationship between various air pollutants and emphysema was measured through computed tomography (CT) lung imaging and lung function testing. Consistent results were found in these varied metropolitan regions, including Winston-Salem, North Carolina, St. Paul, Minnesota; New York City, New York, Baltimore, Maryland, Chicago, Illinois, and Los Angeles, California. Participants came from the Multi-Ethnic Study of Atherosclerosis (MESA), a medical research study, and involved more than 7,000 men and women from the six localities.

The combined health effect of multiple air pollutants ozone, fine particles known as PM2.5, nitrogen oxides, and black carbon, was greater than when the pollutants were assessed individually, said Bonnie Joubert, PhD, a scientific program director at NIEHS.

"With the study's long-running duration, repeated CT scans allowed analysis of changes in emphysema over time,” she said.

Researchers measured all major air pollutants with longitudinal increases in percent emphysema revealed by more than 15,000 CT scans acquired from 2000 to 2018. Over the same period, MESA carefully tracked air pollution. MESA is unique in its meticulous characterization of air pollution exposures along with repeated CT scans of lungs in study participants.

"Air pollution is a significant public health concern around the world," said Gwen Collman, PhD, director of NIEHS' Division of Extramural Research and Training. "It's been a priority of NIEHS research for many years, so it's great when we can accelerate our efforts by joining with other NIH institutes in supporting research on lung disease."

Emphysema is a debilitating disease, and people with emphysema have difficulty breathing along with a persistent cough and phlegm. It makes physical and social activities difficult, creates work hardships, and may result in detrimental emotional conditions. Its development can be a slow, lifelong process. Emphysema is not curable, but treatments help manage the disease. Understanding and controlling emphysema may lead to better treatment, said David Goff, MD, PhD, director of NHLBI's Division of Cardiovascular Sciences.

"We need to assess the effectiveness of strategies to control air pollutants in our efforts to improve heart and lung health," said Goff. "At the same time, people need to remember the importance of a healthy diet, physical activity, and smoking cessation for overall health."