Any doubts harboured about the damage second hand smoke can inflict on the health may be resolved in the minds of skeptics by the results of a new study.
Researchers have shown by using magnetic resonance imaging (MRI) that long term exposure to second hand smoke can be a killer.
The MRI scan used was a special type which uses colours to show damaged and undamaged areas of the lung.
The researchers from the Department of Radiology at the Children’s Hospital, Philadelphia, say long term exposure to second hand smoke causes structural damage to the lungs that significantly increases the risk of lung cancer and emphysema.
Emphysema is a lung disease where the alveoli collapse making it very difficult for enough oxygen to get into the bloodstream and to remove waste carbon dioxide from the bloodstream.
It is common amongst smokers and is a major killer in the U.S., where nearly 14,000 people die from it every year.
The researchers carried out MRIs on 13 current or former smokers, and 45 people who had never smoked a cigarette.
The damage detected was microscopic and not detectable with the usual medical imaging tools.
Of the nonsmokers 22 had been constantly exposed to second hand smoke, either by working in a smokey environment, or living with someone who smoked.
The MRIs showed that 67% of smokers had lung damage, but they also showed that 27% of the nonsmokers who were exposed to second hand smoke on a regular basis also had lung damage.
The researchers found in fact that only 4% of the nonsmokers who had had fewer than 10 years of exposure to second hand smoke had no form of lung damage.
Dr. Chengbo Wang, a physicist from the hospital's Department of Radiology, says it has been suspected for decades that prolonged exposure to secondhand smoke may cause physical damage to the lungs, but until now the methods of analyzing lung changes were not sensitive enough to detect it.
The researchers say the findings also have implications for the 35 per cent of American children who breathe in smoke at home every day and should prompt authorities to tighten up regulations on second hand smoke.
The study was at the annual meeting of the Radiological Society of North America (RSNA), in Chicago by Dr Wang.