Long-term exposure to common air pollutants associated with significant progression of emphysema; according to an 18-year study published in JAMA. “They were surprised to see how strong air pollution’s impact was on the progression of emphysema on lung scans; in the same league as the effects of cigarette smoking, which is by far the best-known cause of emphysema,” Joel D. Kaufman said.

For instance, the researchers found that living in an area that had an ambient ozone level; that was 3 parts per billion (ppb) higher than another location over 10 years linked to an increase in emphysema; that was comparable to 3 years of aging or to smoking a pack of cigarettes per day for 29 years. “Rates of chronic lung disease in this country are going up; and increasingly it is recognized that this disease occurs in nonsmokers,” Kaufman said.

“They really need to understand what is causing chronic lung disease; and it appears that air pollution exposures that are common and hard to avoid might be a major contributor.” For this study, the researchers evaluated the association between resident-specific concentrations of ozone (O3); fine particulate matter (PM2.5), oxides of nitrogen (NOx) and black carbon, as estimated by spatiotemporal models; with % emphysema, as assessed by CT imaging or lung function.

Air pollution concentrations

The cohort included participants in the Multi-Ethnic Study of Atherosclerosis (MESA) Lung and Air studies conducted in Chicago; Baltimore; Winston-Salem, North Carolina; Los Angeles; St. Paul, Minnesota; and New York. Participants were recruited from 2000 to 2002, with additional participants recruited from 2005 to 2007, and follow-up was available through 2018.

Of the 7,071 study participants (mean age at recruitment, 60 years; 47.1% men); 5,780 were assigned outdoor residential air pollution concentrations at baseline and during follow-up and had at least one follow-up CT scan during a median of 10 years. At baseline, median % emphysema was 3% and increased by a mean 0.58 % points per 10 years. Although mean concentrations of PM2.5 and NOx decreased during follow-up, O3 did not.

Overall, results linked greater long-term exposures to air pollutants at baseline and greater exposures to black carbon through 2006 to 2008 to increased progression of emphysema over 10 years. Specifically, % emphysema increased by 0.13 % points per 3 ppb of O3, by 0.11 % points per 2 g/m3 of PM2.5, by 0.06 % points per 10 ppb of NOx and by 0.1 % points per 0.2 g/m3of black carbon.

Faster progression of emphysema

Additionally, a 3 ppb-higher long-term O3 exposure was associated with an increased progression of 0.18 % points in % emphysema over 10 years and a 10 ppb-higher long-term NOx exposure was associated with an increased progression of 0.12 % points in % emphysema over 10 years. However, there was no significant association between PM2.5 and faster progression of emphysema.

Furthermore, 3 ppb in long-term O3 exposure during follow-up was associated with an 18.15-mL greater decrease in FEV1 and a 40.19-mL decrease in FVC over 10 years. Other air pollutants, however, did not appear to be linked to declines in lung function. These findings raise concerns about the effect of the environment on respiratory disease, especially given the growing issue of climate change.

“This is a big study with a state-of-the art analysis of more than 15,000 CT scans; repeated on thousands of people over as long as 18 years. These findings matter since ground-level ozone levels are rising, and the amount of emphysema on CT scans predicts hospitalization from; and deaths due to chronic lung disease,” study author R. Graham Barr, MD, DrPH, professor medicine and epidemiology at Columbia University, said in the release.