Passive smoking has already been linked to respiratory illnesses, cancer and cardiovascular disease. But scientists have now shown deep structural lung damage in nonsmokers exposed to other people's smoke using a special form of MRI.
The 'global helium-3 diffusion MRI' method is unique because people must inhale helium before undergoing imaging.
The MRI scanner measures how far the polarised helium atoms can diffuse through the lungs in 1.5 seconds.
Lung damage means the helium atoms can move further as they have expanded spaces where alveoli are damaged.
For the latest study, 15 smokers and 45 non-smokers with a range of passive smoke exposures were assessed using the technique. Participants were aged 41-79 years.
Almost a third of non-smokers with high exposure to secondhand smoke had lung damage similar to that of smokers, delegates were told at the annual meeting of the Radiological Society of North America in Chicago this week.
The remaining two-thirds of non-smokers had lower diffusion measurement than nonsmokers with low exposure. This may reflect narrowing of the airways as seen in early chronic bronchitis, researchers suggest.
Lead researcher Dr Chengo Wang, a magnetic resonance physicist at the Children's Hospital of Philadelphia, said: 'To our knowledge, this is the first imaging study to find lung damage in non-smokers heavily exposed to secondhand smoke.'
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