Switching to “low-yield” cigarettes, those that yield less nicotine, tar, and carbon monoxide than regular cigarettes when tested on a standard machine, does not, in general, reduce the incidence of heart attack.
Fact 1
Low-yield cigarettes deliver less nicotine, tar, and carbon monoxide when tested on a standard machine.
Fact 2
Nicotine and carbon monoxide contribute to heart disease.
Fact 3 (Paradox)
Switching to low-yield cigarettes does not, in general, reduce the incidence of heart attack.
Evaluate
The mismatch is between machine measurement and real-world exposure. The machine smokes a cigarette in a fixed, standardized way. Real smokers don't. If smokers change their behavior when they switch — drawing more deeply, smoking more cigarettes, taking more puffs — they could end up inhaling the same amount of nicotine and CO as before, even though each cigarette tests as "low-yield." That would explain why heart attack rates don't drop.
Goal
Find an answer showing that real-world exposure to nicotine/CO doesn't actually drop when smokers switch.