This "study" from the American Heart Association is just embarrassing. It claims that, in 18 months, a ban on smoking in workplaces and public buildings decreased total heart attacks by 27 percent in a Colorado city -- largely by reducing second-hand smoke. If that doesn't sound absurd on its face, here's the math, at least as accurately as I could crunch the numbers.
The law could reduce heart attacks in three areas: Smokers who quit because they couldn't smoke in public, smokers who smoked less because they couldn't smoke in public, and non-smokers no longer affected by second-hand smoke.
About 22.6 percent of the area's residents smoked. At up to quadruple the risk of heart disease, that would roughly translate to 54 percent of heart attacks; see below for the math if you're curious.* An aggregation of studies (a "meta-analysis") cited on the CDC's Web site found that public area smoking bans only reduce smoking prevalence in employees by 3.8 percent. So around 3.8 percent times 54 percent, 2 percent, of the old total heart attack population stopped smoking before disaster struck. We'll assume that quitting completely eliminated the effects of prior smoking. Only 25 percent to go.
The same study showed that smoking bans decreased cigarettes-per-day in those who continued to smoke by 3.1. The average smoker smokes 13.2 cigarettes a day, but cutting back does not help when it comes to heart disease except between 0 and 4 cigarettes per day. So scratch that for the 62.9 percent of smokers who inhale daily, an average of 17.5 times a day. We'll say that the remaining 37.1 percent cut their chances of a heart attack by 50 percent -- generous because, in my experience, non-daily smokers tend to be young folks who only smoke when they drink. Whatever they did to their future risks, they didn't avoid heart attacks in the last 18 months. So of the 52 percent of heart attack victims who smoked and didn't quit, 37.1 percent reduced their risk by 50 percent. This translates to a 9.6 percent drop in heart attacks.
Finally, of the 500,000 people who die from coronary heart disease every year in this country, only 35,000 of them (7 percent) are even alleged by the AHA to have been killed by second-hand smoke. We'll assume second-hand smoke completely disappeared in this Colorado town.
So, the best publicly available numbers predict a decline of 7 + 9.6 + 2 = 18.6 percent. I don't doubt the ban had some effect, as it likely did reduce both first-hand and second-hand smoke to some degree, but 27 percent is laughable.
Especially when you consider all the ways I skewed the data to benefit the anti-smoking crowd -- smokers increase their risk of heart disease by two to four times, and I used four. Based on that, 54 percent of heart attack victims smoke, but not all of those attacks are caused by smoking as I assumed (unfortunately, some would've had heart attacks anyway). Second-hand smoke really wasn't completely eliminated, and like I said, the light smokers who went even lighter were probably young people who wouldn't have had heart attacks from smoking for years. Finally, there is some overlap between those I defined as light smokers who went lighter (the 37.1 percent) and those the smoking ban study found quit, so the effects of the ban are double-counted.
I interviewed Reason editor and author Jacob Sullum about a similar "study" for a college paper; read it here.
Robert VerBruggen blogs at http://robertsrationale.blogspot.com.
*Assume a population of 1,000, where 226 folks smoke. 40 percent of the smokers, and 10 percent of everyone else, get heart disease in a given year (just for the sake of round numbers). That's 22.6 x 4 = 90.4 smokers and 77.4 nonsmokers with coronaries. 90.4 + 77.4 = 167.8. 90.4/167.8 = 54 percent of victims are smokers.
Powered by Qumana
0 comments:
Post a Comment