Secondhand Smoke Is Not Nearly As Dangerous As We Thought
Smoking bans are trendy. But do they make sense?
“Only tobacco companies would fight cutting heart attacks in half.”
This is the headline for an advertisement sponsored by the Bismarck Tobacco Free Coalition, the American Cancer Society, the American Heart Association, the American Lung Association and the Robert Wood Johnson Foundation.
The ad alleges that secondhand smoke kills 53,000 Americans every year. It also mentions a smoking ban in the city of Helena, Montana “cut the incidence of heart attack by 40% in six months.”
The claim that Helena’s smoking ban reduced heart attacks by almost half comes from a well-known study that was largely responsible for bringing the dangers of second-hand smoke to the attention of the general public. The findings of the study, which was performed in 2002, catalyzed a number of smoking bans across the country.
The problem is, the study has been widely discredited.
Between June and December of 2002, Montana’s capital city (pop. 68,000) enacted a smoking ban that applied in workplaces, bars, restaurants and casinos. Shockingly, during this time heart attacks in Helena plunged nearly 60%. In November 2002, a judge overturned the ban and heart attacks once again increased.
In 2003, doctors from Helena’s local hospital published their findings and the world took note: Reputable publications like the New York Times and BBC covered the story. Anti-smoking advocates used the research to justify pushing for more stringent smoking bans all over the country. Scientists performed similar studies across the United States, from Colorado to Indiana that echoed Helena’s results.
The Helena Miracle, as it came to be known, clearly suggests that secondhand smoke is damaging and that limiting exposure is powerful enough to significantly improve a person’s cardiac health. Tobacco control groups argued that just half an hour of exposure to secondhand smoke could be as dangerous as engaging in a lifelong smoking habit.
As time went on, however, it became quickly apparent that the Helena study was flawed: In 2004, the paper was republished in the British Medical Journal. Here, researchers adjusted the number of heart attack reductions from 60% to 40%.
Scientists across the world were skeptical about Helena’s findings and sought to investigate the claim on their own. But as researchers examined larger populations, they discovered smaller reductions in heart attacks. A study out of the Piedmont region of Italy uncovered a decline of 11% — and that was only for residents over age 60. In 2007, England put in place a nationwide smoking ban, but only credited it with reducing heart attacks by 2% across the country. After New Zealand enacted a smoking ban in 2004, hospitalizations for cardiac issues actually increased.
In 2010, the think tank RAND Corporation published a paper hypothesizing that the drop off in heart attack rates after smoking bans were enacted were due — in large part — to chance. In their study, researchers said they had found “no evidence that legislated U.S. smoking bans were associated with short-term reductions in hospital admissions” for heart attacks or other diseases in the elderly, children or working age adults.
The small sample size of Helena’s study misled researchers, allowing fluctuations in data to be misconstrued as real results. These early forays into analyzing the effects of secondhand smoke failed to explain why heart attack rates ebb and flow, immaterial of smoking bans. Most importantly, none of the studies accounted for bias: Researchers had no reason to believe that inhaling secondhand smoke might decrease or have no effect on the risk of heart attack, so nobody bothered to investigate this possibility.
In August, Vivian Ho — an economist at Rice University in Texas — published a paper contrasting hospitalization rates in areas that have smoking bans with areas that don’t. Ho’s team examined data from 28 states between 2001-2008, and found a reduction in hospitalizations for people over the age of 65 after lawmakers enacted smoking bans.
But here’s the important part: After adjusting for additional variables — such as cigarette taxes and access to hospitals — Ho discovered that these reductions disappeared. Her team said that improvements in cardiac health could be attributed to greater access to medical care and the rising price of cigarettes (which meant people were smoking less).
In a recent piece for Slate, the Oregon-based writer Jacob Grier, who covers public policy issues, argued that enacting smoking bans based on overstated information stigmatized smokers and violated their rights.
But the tide of public opinion was already turning against smoking even before the Helena study came to light. It’s likely that legislators would have implemented similar bans, regardless of the publicity brought on by the Helena Miracle.
Smoking bans are important for public health and it’s crucial they remain in place. But if we exaggerate the negative health effects of second-hand smoke, we’re misleading ourselves and our children and will only wind up farther from the truth.