Boston University physician Michael Siegel goes against the grain on the effects of second-hand smoke:

Siegel has just published a heretical paper in the journal Epidemiologic Perspectives & Innovations analyzing the purported effects of secondhand smoke. Siegel – the kind of doctor who can cure you, not the Dr. Kissinger type – writes that “there appears to be no scientific basis for claims that brief, acute, transient exposure to secondhand smoke increases heart attack risk in individuals without coronary disease . . . that it can cause atherosclerosis, that it can cause fatal or catastrophic cardiac arrhythmias, or that it represents any other significant acute cardiovascular health hazard in nonsmokers.”