Air pollution can be as damaging as a packet of cigarettes a day, a new study has found.
Researchers from the University of Washington looked at how exposure to four main pollutants affected lung health in 7,071 adults aged 45 to 84 living in six US city areas.
Following up on the participants for an average of 10 years, they measured levels of fine particulate matter, nitrogen oxide, black carbon and ozone outside their homes and carried out CT scans to track the development of emphysema and lung decline.
The study found that long-term exposure to all of the pollutants was linked to an increased percentage of emphysema, with ground level ozone in particular leading to a decline in lung function.
Ground-level ozone is produced when UV light reacts with pollutants from fossil fuels, and the process is accelerated by heatwaves.
In areas with increased levels of ozone, the research found an increase in emphysema roughly the equivalent of smoking a pack of cigarettes a day for 29 years.