Ozone air pollution was associated with a significant increase in emphysema. Lung scans of more than 7,000 participants were compared across 6 metropolitan regions in the US and air pollution levels were measured at the homes of study participants.

This was a big study with analysis of more than 15,000 CT scans repeated on thousands of people over 18 years.

The study also found that if the ambient ozone level was 3 parts per billion higher where you live compared to another location over 10 years, that was associated with an increase in emphysema roughly the equivalent of smoking a pack of cigarettes a day for 29 years.

This study was a large prospective study so causation cannot be established. However, the authors developed novel and accurate exposure assessment methods for air pollution levels at the homes of study participants, collecting detailed measurement of exposures over years in these metropolitan regions, and measurements at the homes of many of the participants which strengthen the data.