Slate clocked in with a post about how smokers do not believe that secondhand smoke is dangerous. I’m one of them, for certain values of “dangerous.” This puts me at odds with publicized scientific research, so I conducted an imaginary dialog with myself explaining my position.

Self: So you don’t think secondhand smoke is harmful?

Jeff: Compared with ordinary air? Sure, it’s probably more dangerous. But you can be “more dangerous” without rising to the level of “actually harmful.”

Self: That’s an awfully qualified position.

Jeff: That’s because I’m awfully qualified.

Self: I think you misunderstood me….

Jeff: No, seriously. The average human lung can exhale around a liter of air, on a two-second cycle. Compare that with the average exhaust tail on an automobile.

Self: They’re hardly comparable.

Jeff: Exactly. An exhaust tail is spitting out massive amounts of carbon monoxide every second that a car is in use. I’m writing this while sitting next to a road that handles thousands of cars an hour. I find it literally incredible that air quality near me is reduced more by three cigarettes than it is by those thousands of cars.

Self: So would you say that secondhand smoke is “not too harmful,” then?

Jeff: It doesn’t make a damn bit of difference what I think. Science isn’t a poll, dammit. But based on the mechanisms behind creating secondhand smoke and creating secondhand vehicle exhaust, I have trouble understanding why the former is a big media issue, but the latter is almost never mentioned.

Self: What do you think of all of those studies, then?

Jeff: I try to keep up on them, but I think we’re all subjected to selection bias. That is, research about secondhand smoke is likely to be picked up by the news and cross our radars. The idea that “cars make smog” isn’t newsworthy, so we’re not going to hear about that. This also affects the studies of secondhand smoke, unless the universal impact of that pollutant is controlled for in those studies.

Self: And is it?

Jeff: I don’t know. I’m talking out of my ass. But I suspect not.