It’s not a smoking gun, but it’s smoking-related, and it’s there in bright medical images: evidence of microscopic structural damage deep in the lungs, caused by secondhand cigarette smoke. For the first time, researchers have identified lung injury to nonsmokers that was long suspected, but not previously detectable with medical imaging tools. The researchers suggest that their findings may strengthen public health efforts to restrict secondhand smoke. “We used a special type of magnetic resonance imaging to find these structural changes in the lungs,” said study leader Chengbo Wang, Ph.D., a magnetic resonance physicist in the Department of Radiology at...