A week ago we defended a colleague against attacks from overzealous anti-smoking crusaders when he criticized their patently absurd claim that breathing 30 minutes of second hand smoke in a public place was equivalent heart attack risk to that of a smoker. Some interpreted this as our saying second hand smoke was not as bad as alleged. I suppose the question here is “alleged by whom,” but we don’t have to play those games. Second hand smoke is bad for the health of those exposed to it for any length of time, as a new study shows graphically — literally:
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 studied 60 adults between ages 41 and 79, 45 of whom had never smoked. The 45 non-smokers were divided into groups with low and high exposure to secondhand smoke; the high-exposure subjects had lived with a smoker for at least 10 years, often during childhood. The 15 current or former smokers formed a positive control group.
The research team prepared an isotope of helium called helium-3 by polarizing it to make it more visible in the MRI. Researchers diluted the helium in nitrogen and had research subjects inhale the mixture. Unlike ordinary MRIs, this MRI machine measured diffusion, the movement of helium atoms, over 1.5 seconds. The helium atoms moved a greater distance than in the lungs of normal subjects, indicating the presence of holes and expanded spaces within the alveoli, tiny sacs within the lungs. (Sciencedaily)
Figure: On the left (a) low exposure to second hand smoke, (b) high exposure to second hand smoke, (c) smoker or former smoker. Red areas generally normal, yellow areas abnormal. (Credit: Children’s Hospital of Philadelphia and the University of Virginia, via Sciencedaily)
Using this ingenious method, a third of non-smokers with prolonged exposure to second-hand smoke showed the kinds of structural changes typical of smokers, interpreted as a mild form of emphysema. Two-thirds of high exposure non-smokers also had reduced diffusion, possibly a sign of chronic bronchitis. Either way, exposure to second hand smoke has an effect and the effect doesn’t appear to be benign or inconsequential.
What this means exactly will take time to sort out. But it doesn’t let second hand smoke off the hook. On the contrary.