Tuesday, November 27, 2007

Doing the math on secondhand smoke

slide rule
In the case of passive smoking, a relative risk increase of 30 percent is important because it affects the number one disease, because it affects innocent people against their will, and because it is easily preventable.

The evidence is overwhelming. In a review of 29 studies, Barnoya and Glantz (Circulation 2005) have calculated a relative risk of 1.3, that is an increase by 30 percent, for coronary heart disease, caused by long-term exposure to secondhand smoke. Coronary heart disease will affect every second man and every third woman after forty years of age. Translated to absolute lifetime risks, passive smoking may increase them by 15 percent in men (every seventh) and by 10 percent in women (every tenth) in case of a lifelong exposure. This is highly relevant, completely different from the cancer and obesity case reported earlier - "Selling molehills as mountains".

Paid scientists and skeptics

In the past years, the tobacco industry has tried to sow controversy about the facts, paying scientists and funding research. Some results of flawed studies reporting a null effect of secondhand smoke have been published, and paid skeptics have done their best in denying the dangers of passive smoking.

Is Michael Siegel who runs the Tobacco Analysis blog one of them? When I first visited his blog, back in April, I couldn't make up my mind. The comments on his blog are mainly from tobacco freedom activists and I have seen much applause from this side. But then I came to the conclusion that he is honest and not a paid skeptic. I just have visited his blog again today and have seen that he is being trolled by them. This, and his most recent publication, convince me that I judge him properly: He says that "chronic exposure to secondhand smoke has been well recognized as a cause of heart disease in nonsmokers" but he blames the anti tobacco activists for having made exaggerated claims about short-term effects of passive smoking. Overstated claims undermine credibility and help Big Tobacco. Thus, I conclude that he is doing a good job.

Harm against their wills

Besides math and health statistics, the legal aspect is another big point here. Passive smoking harms people against their wills. Smokers can decide not to smoke, passive smokers cannot. They are forced to breathe the contaminated air, filled with fine dust and poisons. Many of them are children or older people. Some are particularly vulnerable like asthmatics and other lung patients.

Easily preventable

All over the world, public smoking bans have been accepted by smokers with a nearly hundred percent compliance. The positive effect of such bans are beyond any doubt. And the majority of the population wants such regulations. Here in Switzerland, lagging behind the most part of Europe, two cantons have voted for public smoking bans last weekend, and a national legislation is under way.

The effect can already be seen in health studies: A study on secondhand smoke and heart attacks failed to show a connection because the exposure, due to smoking bans, has declined sharply in the recent years.

Photo credit: flickr.com/photos/rogersmith/53912456/

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