While I can appreciate the usefulness of smoking bans, especially as it relates to non-smokers (or even smokers for that matter).  I'm not convinced that the science is establishing a sound cause and effect linkage.

There is little doubt that smoking is not a healthy activity, but similarly we should be aware of all forms of air pollution.  A recent study suggested that even a relatively brief exposure to second hand smoke could precipitate a heart attack1.  Unfortunately, I haven't seen how such a study or determination was made, so it is impossible to assess their methodology.  

Consider the following quote:
"The Centers for Disease Control and Prevention (CDC) has concluded that smoke-filled rooms may have up to six times the air pollution of a busy highway. And secondhand smoke inside a car can be more toxic than rush hour exhaust fumes."
While I can fully concur with the notion of smoking inside a vehicle and smoke-filled rooms, this quote also suggests that there may be other toxins in the air that are being ignored.  I can appreciate the problems of second hand smoke, but I am suspect that any such study has the ability to differentiate between second hand smoke and other environmental toxins to such a high degree.

In fact, I suspect that no such linkage has been established.  Instead, I expect that smoking bans are easier (and less economically costly) to implement than making pollution free cars, so it represents any easy target.  It is inconceivable that an individual can spend one or two hours a day in a car breathing in automobile exhaust and suffer no consequences and yet even a light exposure to second hand cigarette smoke may cause a heart-attack.  When this is coupled with living in cities that may have any number of annual warnings regarding air quality hazards, and particulate matter from wildfires (as in California), one has to wonder how the data set connecting second-hand smoke could be kept so independent of all these other variables.

In particular, one study suggested that environmental tobacco smoke was up to ten times higher than exhaust from an idling engine.  However, the engine was an "ecodiesel" engine, so I guess the results might have been a bit different had a standard automobile been used.
"Conclusions: ETS is a major source of PM pollution, contributing to indoor PM concentrations up to 10-fold those emitted from an idling ecodiesel engine"

NOTE:  ETS = Environmental Tobacco Smoke and PM = Particulate Matter
Neglecting the fact that normal traffic situations rarely involve one car, nor do they entail three cigarettes in 30 minutes and invariably they don't occur in closed rooms.  Other than that, the comparison seems entirely appropriate.

While I am no advocate for smoking, it seems that this is simply a distraction to avoid dealing with the much larger issues of air pollution.  Tobacco is an easy target and the economic consequences aren't considered to be significant or relevant.  
"In most cities across the globe, the personal automobile is the single greatest polluter. Emissions from a billion vehicles running each day add up to a planet-wide problem. Breathing is fairly important for all of us and driving cars is our biggest single air polluting activity."
"The greatest possibility for high-level exposures is in the workplace... most people are exposed to benzene in tobacco smoke and automobile exhaust."
Sorry, but in this case, I have to come down on the skeptical side of this study.  Unless the individuals studied have never lived in large cities, or been around cars, or have never been exposed to air pollution of any type, it is presumptious to suggest that anyone can link a heart attack to one definitive cause, such as second-hand smoke.

1"Although there is no direct evidence that a relatively brief exposure

to secondhand smoke could precipitate a heart attack, the committee

found the indirect evidence compelling."