Researchers say for the first time they have evidence that long-term exposure to secondhand smoke can cause structural damage in the lungs that is indicative of emphysema.

According to Reuters, the study says one third of people who breath in high levels of secondhand smoke have damage to their lungs similar to that seen in smokers.

They used a special kind of magnetic resonance imaging, or MRI, scan to look at the lungs of non-smokers who had high exposure to other people’s cigarette smoke and found evidence of the kind of damage that causes emphysema, reports said.

Reuters said the researchers interpreted the changes as early signs of lung damage, representing very mild forms of emphysema.

“Almost one third of nonsmokers who had been exposed to secondhand cigarette smoke for a long time developed these structural changes,” said Chengbo Wang, a magnetic resonance physicist at The Children’s Hospital of Philadelphia, who led the study.

Reuters reported the researchers studied 60 adults between ages 41 and 79, 45 of whom had never smoked. The non-smokers were considered to have high exposure if they had lived with a smoker for at least 10 years, often during childhood.  They found that 57 percent of the smokers and 33 percent of the nonsmokers with high exposure to secondhand smoke had signs of early lung damage as measured by the scan.

Wang presented his team’s findings to a meeting of the Radiological Society of North American in Chicago, Reuters said.