The Most Misleading Claim of them All: Secondhand Smoke Can Cause Instant Death

Perhaps the most misleading claim of all those being made by anti-smoking groups is the claim that two hours of secondhand smoke exposure can cause instant death by triggering a fatal cardiac arrhythmia. Given the severe nature of this alleged effect of secondhand smoke on the population, I feel it deserves its own post.

First of all, you can see why this particular claim would be appealing to anti-smoking groups. After all, you can't have a health effect that is more serious than sudden death. If it is true that just two hours of exposure is enough to cause an otherwise healthy person to drop dead instantly, then let's face it - there's no justification for allowing smoking in any public place. We simply couldn't take that chance.

Yet that is exactly what a number of anti-smoking groups are implying is the case - that 2 hours of secondhand smoke exposure can cause sudden death in any nonsmoker by triggering a fatal cardiac arrhythmia.

Tobacco Scam: "120 minutes = greater risk of irregular heartbeat...Breathing secondhand smoke also can speed up your heart rate while, at the same time, reducing "heart rate variability" - small, random variations in heartbeat. While the mechanism is not yet fully understood, reductions in heart rate variability signal problems in the nervous system's control of the heart, increasing the chance of an irregular heart beat (arrhythmia) that can itself be fatal or trigger a heart attack."

Smoke Free Catawba: "2 Hours of Exposure = Greater Risk of Irregular Heartbeat...Breathing secondhand smoke can speed up your heart rate and reduce “heart rate variability” – small, random variations in heartbeat. Reductions in heart rate variability signal problems in the nervous system’s control of the heart, increasing the chance of an irregular heart beat (arrhythmia) that can itself be fatal or trigger a heart attack."

Coalition for a Tobacco Free Hawaii: "120 minutes = greater risk of irregular heartbeat...Breathing secondhand smoke also can speed up your heart rate while, at the same time, reducing "heart rate variability" — small, random variations in heartbeat. While the mechanism is not yet fully understood, reductions in heart rate variability signal problems in the nervous system’s control of the heart, increasing the chance of an irregular heart beat (arrhythmia) that can itself be fatal or trigger a heart attack."

University of North Carolina School of Medicine: "2 hours of exposure = greater risk of irregular heartbeat...Breathing secondhand smoke can speed up your heart rate and reduce “heart rate variability”—small, random variations in heartbeat. Reductions in heart rate variability signal problems in the nervous system’s control of the heart, increasing the chance of an irregular heart beat (arrhythmia) that can itself be fatal or trigger a heart attack."

American Heart Association: "2 hours exposure = greater risk of irregular heartbeat…Breathing secondhand smoke can also speed up your heart rate while, at the same time, reducing ‘heart rate variability’—small, random variations in heartbeat. While the mechanism is not yet fully understood, reductions in heart rate variability signal problems in the nervous system’s control of the heart, increasing the chance of an irregular heart beat (arrhythmia) that can itself be fatal or trigger a heart attack."

Apparently, these claims have been picked up by the media, leading to even more misleading claims to the public. For example, two newspapers' opinion pieces actually went so far as to suggest that the Centers for Disease Control and Prevention (CDC) had stated that two hours of secondhand smoke exposure can cause a fatal or catastrophic arrhythmia (which is not true):

Bluff County Newspaper Group: "According to the Centers for Disease Control, ... two hours of exposure can speed up the heart rate and reduce heart rate variability, increasing the chance of an irregular heart beat (arrhythmia) that can itself be fatal or trigger a heart attack."

Spring Grove Herald (January 2, 2007): "According to the Centers for Disease Control, ... two hours of exposure can speed up the heart rate and reduce heart rate variability, increasing the chance of an irregular heart beat (arrhythmia) that can itself be fatal or trigger a heart attack."

These statements imply that brief secondhand smoke exposure causes fatal or catastrophic arrhythmias in nonsmokers. The public would reasonably infer that such fatal arrhythmias (i.e., sudden death) can occur in anyone exposed to secondhand smoke, not merely someone who has severe pre-existing heart disease that makes him or her extremely susceptible to exposures that could trigger an arrhythmia.

The Rest of the Story

You knew it had to happen. Anti-smoking groups have been so anxious to scare the public about the acute hazards of even a brief exposure to secondhand smoke in order to promote smoking bans that they have distorted the science and exaggerated the cardiovascular effects of tobacco smoke: the time that it apparently takes for secondhand smoke to cause a heart attack has dropped from 30 minutes to 20 minutes to 5 minutes and ultimately, to 30 seconds.

But now, it turns out that a number of anti-smoking groups are claiming that secondhand smoke exposure can actually cause instant death - by triggering fatal or catastrophic cardiac arrhythmias. And none of these claims is qualified by suggesting that the alleged risk of sudden death applies only to individuals who already have severe, pre-existing heart disease and thus are susceptible to even minor insults that could trigger an arrhythmia.

How did anti-smoking groups come up with this claim?

By a wild stretch and distortion of the science, that's how.

It turns out that there was one study which showed that a 2-hour exposure to secondhand smoke reduced heart rate variability in healthy nonsmokers. In the study, nonsmokers spent 2 hours in an enclosed smoking area at the Salt Lake City Airport. The study did show that this exposure reduced heart rate variability. However, the clinical significance of this finding with regards to an acute exposure is nil. None of these exposed nonsmokers was at risk of suffering a fatal cardiac arrhythmia because of this change in heart rate variability. If they were, then it would have been unethical to conduct this study without prolonged cardiac monitoring, defibrillation equipment on the premises, and a signed consent form in which subjects were told that this experiment could kill them. Obviously, such an experiment could never be done.

The relevance of this study, therefore, is in terms of the effects of chronic exposure. Once again, this study provides a potential mechanism for the observed increase in heart disease risk among individuals chronically exposed to secondhand smoke (see Pope CA, Eatough DJ, Gold DR, et al. Acute exposure to environmental tobacco smoke and heart rate variability. Environmental Health Perspectives 2001; 109:711-716). But it does not indicate that a short-term exposure puts any nonsmoker at risk of suffering a fatal cardiac arrhythmia.

It is important to point out that air pollution also decreases heart rate variability, in a very similar way to the findings observed due to secondhand smoke. There are at least 3 studies which have documented that particulate air pollution changes heart rate variability, just like secondhand smoke; however, one wouldn't warn the public that exposure to air pollution may trigger a fatal or catastrophic arrhythmia (see Liao D, et al. Environmental Health Perspectives 1999; 197:521-525; Gold DR et al. Circulation 2000; 101:1267-1273; Pope CA et al. American Heart Journal 1999; 138:890-899).

Just as with secondhand smoke, these studies demonstrate a plausible biologic mechanism by which chronic exposure to particulate air pollution could contribute to the development of heart disease.

There are other factors that, like secondhand smoke, contribute to decreased heart rate variability. But I don't see any groups warning the public that these factors, on a short-term basis, can cause someone to drop dead.

Anxiety, hostility, and stress also reduce heart rate variability (see: Kawachi I, Sparrow D, Vokonas PS, Weiss ST. Decreased heart rate variability in men with phobic anxiety. Am J Cardiol 1995; 75: 882-885; and Offerhaus RE. Heart rate variability in psychiatry. In: RJ Kitney, Rompelman O (eds). The Study of Heart Rate Variability. Oxford: Oxford University Press, 1980: 225-238). These studies have properly been interpreted as providing a potential mechanism for the observed relationship between anxiety/stress and coronary heart disease.

These studies do not mean that we should be warning the public that becoming anxious about something can cause you to drop dead instantly of a cardiac arrhythmia.

Yet if we were to use the same "logic" being used by anti-smoking groups to support their claims, we would also be warning people that going outside in a city with high levels of air pollution could cause sudden death.

The chief significance of reduced heart rate variability is that it is a measure of cardiac autonomic function and it appears to correlate with reduced survival following acute myocardial infarction (heart attack). It is certainly a potential biologic mechanism by which chronic secondhand smoke exposure could contribute to increased heart disease mortality, as has been observed in epidemiologic studies. But by no means does this study result mean that if a person, not in the wake of just having suffered a heart attack, is exposed to secondhand smoke for 2 hours, he or she is at risk of dropping dead instantly from a fatal cardiac arrhythmia.

To show how absurd these claims are, consider the fact that the following factors have all been shown to affect cardiac autonomic function, just like secondhand smoke in the Pope et al. study:

• Thoughts and even subtle emotions;
• Activity of the digestive, cardiovascular, immune and hormonal systems.
• Negative reactions
• Positive feelings such as appreciation

According to anti-smoking groups, then, reading this blog could potentially trigger a fatal cardiac arrhythmia in a reader, since it is well-documented that if this blog post induces anger, it could well lead to a reduction in heart rate variability, which according to anti-smoking groups, puts the reader at increased risk for a fatal cardiac arrhythmia.

So perhaps I need to put a disclaimer on this blog:
Reading The Rest of the Story could kill you.

There! Now you have all been warned.

On the bright side, positive feelings like appreciation can actually restore cardiac autonomic balance, such as heart rate variability. So let me say that I appreciate all of you.

There! I've just saved several lives.

It's a sad state of affairs when this is the kind of weak, exaggerated, and distorted scientific reasoning that supports the claims being made by prominent anti-smoking groups.