Image of the lungs to illustrate individuals with fibrotic interstitial lung disease made worse by air pollution
Credit: artacet / Getty Images

A study led by University of Pittsburgh researchers shows a significant link between air pollution exposure and faster disease progression and death in patients with fibrotic interstitial lung disease (fILD).

The study also adds weight to previous research linking air pollution with the onset of this kind of lung disease, the cause of which is often unclear.

“Some people with these lung diseases have an expected lifespan from diagnosis to death of only a few years, and yet it’s a mystery as to why they developed the disease, why their lungs become so scarred,” said Gillian Goobie, a doctoral candidate in the Pitt School of Public Health’s Department of Human Genetics, who is also first author on the JAMA Internal Medicine paper describing the study.

“Our study points to air pollution—specifically pollutants from factories and vehicles—as potentially driving faster disease progression and premature death in these patients.”

The multicenter, international, prospective cohort study included 6683 people with fILD. These were split across three groups: the Simmons (1424 people), Pulmonary Fibrosis Foundation (1870 people); and Canadian Registry for Pulmonary Fibrosis (3389 people) cohorts.

Over a median of three years follow up, 28% of all the patients died and 10% needed a lung transplant. The team assessed the association of particulate matter 2.5 μm or less in diameter (PM2.5) with outcomes among the patients. Measurements of PM2.5 were recorded in the area the patient was resident five years before death, lung transplant, or cessation of follow-up.

A PM2.5 exposure of 8 μg/m3 or more was associated with a 4.40-, 1.71- and 1.45-fold increased risk for death in the Simmons, Pulmonary Fibrosis Foundation, and the Canadian Registry for Pulmonary Fibrosis cohorts, respectively, compared with lower exposures.

Exposure to sulfate, nitrate, and ammonium particulate matter of this size increased risk for death in all the groups and tended to be linked to the worst outcomes in individuals with fILD. In contrast, exposure to PM2.5 particles made up of more natural particles such as soil or sea salt did not appear to be as harmful.

“In the past, most environmental health research has focused on the simple definition of PM2.5 as anything of that size,” said co-author James Fabisiak, associate professor in Pitt Public Health’s Department of Environmental and Occupational Health, in a press statement.

“But PM2.5 is chemically diverse, with a different composition depending on whether it came from a forest fire or a tailpipe. Research has lacked in determining if the type of PM2.5 matters when it comes to health effects. Our new research is a big step toward filling in that knowledge gap.”

Adverse effects of air pollution on lung disease have been suspected for some time, but this study helps to show conclusively that exposure to specific types of PM2.5 particles worsens health and increases risk for death in these vulnerable individuals.

“Ultimately, we want to encourage a data-driven awareness,” said co-senior author S. Mehdi Nouraie, associate professor of pulmonary, allergy and critical care medicine at Pitt’s School of Medicine. “We want people to think about the quality of the air we breathe. Patients, health care providers and policymakers can all use the new information we’re providing to try to improve health outcomes. When you make the air safe for the most vulnerable to breathe, you’re making it safe for all of us.”

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