Chengbo Wang, a magnetic resonance physicist at The Children's Hospital of Philadelphia, said, "Almost one third of nonsmokers who had been exposed to secondhand cigarette smoke for a long time developed these structural changes," Wang added in a statement.
"To our knowledge, this is the first imaging study to find lung damage in non-smokers heavily exposed to secondhand smoke. We hope our work strengthens the efforts of legislators and policymakers to limit public exposure to secondhand smoke."
Wang, who presented his team's findings to a meeting of the Radiological Society of North American in Chicago, said 35 percent of U.S. children live in homes where someone smokes regularly.
The team 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.
"It's long been hypothesized that prolonged exposure to secondhand smoke may cause physical damage to the lungs, but previous methods of analyzing lung changes were not sensitive enough to detect it," said Wang.
His team used a technique called long-time-scale, global helium-3 diffusion magnetic resonance imaging.
"With this technique, we are able to assess lung structure on a microscopic level," Wang said.
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.
In February, U.S. researchers reported that up to 20 percent of women who develop lung cancer have never smoked.