No Facts to Back Up This Secondhand Smoke Claim

This claim and more.

The pervasive claim that secondhand smoke is 23 times more toxic in cars than in the home does not appear to be based on scientific evidence.

The widely reported 'fact' appears to have originated in a 1998 Rocky Mountain News story about proposed legislation to ban smoking in cars containing children, according to Ross MacKenzie, MA, and Becky Freeman, MSc, of the University of Sydney School of Public Health in Australia.

In the story, the state legislator who introduced the legislation was quoted as saying she had become concerned about the issue upon hearing the now ubiquitous claim.

The statement continues to pop up in the medical literature, on government and advocacy organization Web sites, and in the mass media to this day.

However, MacKenzie and Freeman were unable to find an original scientific source for the figure.

Perpetuation of the claim presents a credibility problem, MacKenzie and Freeman wrote in an analysis in CMAJ.

Still think you should believe what the experts say?