Although scientists have long understood that no level of exposure to cigarette smoke is safe, they have been unable to detect the amount of lung damage caused by secondhand smoke. Chengbo Wang from The Children’s Hospital of Philadelphia and his colleagues recently used long-time-scale global hyperpolarized helium-3 diffusion MRI to investigate whether they could detect the effects of secondhand smoke in the lungs.As presented in November at the Radiological Society of North America meeting, the researchers studied the lungs of 60 adults: 45 nonsmokers (23 of whom had a low exposure to secondhand smoke and 22 with a high exposure) and 15 current or former smokers. Each patient inhaled a specially prepared helium gas prior to imaging with a Siemens 1.5-T MRI scanner. Magnetic resonance measured how far the helium atoms moved, which revealed the amount of damage present in the lungs. Secondhand exposure causes the small airways and sacs in the lungs to break down, develop holes or become inflamed, allowing helium atoms to travel farther than they would in healthy lungs. The investigators measured the amount of travel over ~1.5 s and converted the scores to apparent diffusion coefficient values, where higher values indicated more lung damage. Smokers had an average apparent diffusion coefficient value of 0.033, and nonsmokers with high exposure had an average value of 0.020, indicating probable lung damage for both groups compared with an average apparent diffusion coefficient value of 0.018 for nonsmokers with low exposure. The researchers concluded that the effects of secondhand smoke can be detected using the technique and that secondhand cigarette smoke exposure can seriously damage the lungs.