Recently the British Medical Journal published an article that claimed smoking in a car was 23 times more toxic than a smokey bar. However, they then retracted and came up with a new number of 11 times more toxic than a smokey bar. When you actually look at the study it does not take into consideration the outside pollution levels. I suspect they didn’t because if they did the reading would actually be a minor blimp and nothing more.
Once the "appropriate scare tactic" has been published the retraction and lack of outdoor pollution consideration will never be changed, it will be quoted forever as 23 times more toxic.