Long-term exposure to outdoor air pollutants accelerates the development of emphysema and age-related decline in lung function, new research shows.
The 18-year study involving 5780 adults across several centres in the US found a statistically significant association between baseline ambient concentrations of ambient ozone (O3; 0.13 per 3 parts per billion), fine particulate matter (PM2.5; 0.11 per 2 μg/m3 ), oxides of nitrogen (NOx; 0.06 per 10 parts per billion), and black carbon (0.10 per 0.2 μg/m3) with greater increases in emphysema over 10 years.
The findings were most robust and of greatest magnitude for O3, the researchers reported in their paper published in JAMA.
In an analyses of air pollutant exposure over follow-up, a 3 parts per billion (ppb) – higher long-term mean O3 exposure assessed over follow-up was significantly associated with an increased progression of 0.18 percentage points in per cent emphysema over 10 years.
“This increase is equal to the association of 29 pack-years of smoking (each 10 pack-years of smoking was significantly associated with an increased progression of 0.06 percentage points of per cent emphysema) or 3 years of aging in this cohort,” they wrote.
“Because long-term concentrations of O3 at current levels were strongly and consistently associated with both progression of emphysema and decline in lung function in this study, more effective control strategies to reduce O3 concentrations may be needed to protect lung health,” the researchers wrote.
The association between pollutant concentrations over follow-up and faster progression of per cent emphysema was also statistically significant for NOx (increase, 0.12 percentage points per 10 ppb, but not for PM2.5 (increase, −0.04 per 2 μg/m3).
Per cent emphysema, defined as the per cent of lung pixels less than −950 Hounsfield units, was assessed up to 5 times per participant via cardiac CT scan (2000-2007) and equivalent regions on lung CT scans (2010-2018). Spirometry was performed up to 3 times per participant (2004-2018).