Evidence of the impact of California's 2007 smokefree vehicle law

Background. Four states (including California) and Puerto Rico have banned smoking in vehicles when minors are present. Proponents assert that such laws will reduce child exposure to secondhand smoke but evidence for this claim is wanting. If these laws are effective, then children in states with these laws should report significantly reduced exposure to smoking after implementation of the law.

Methods. Using data from the biennial California Student Tobacco Survey (CSTS), we investigated the impact of California's smokefree vehicle law. California adopted the law in October 2007 and fully implemented it on January 2, 2008. Since 2001, the CSTS has been surveying 6th-12th graders about exposure to smoking in a car in the last 7 days. Evidence from the National Youth Tobacco Survey (NYTS) indicated a secular trend towards reduced child exposure to smoking in cars. We hypothesized that the corresponding trend in California accelerated after the 2005 CSTS administration.

Results. The proportion of California students reporting exposure to smoking in cars in the last 7 days declined 1% per year from 2001 (24.7%) through 2005 (23.8%), but declined 5.8% per year from 2005 through 2009 (18.3%). The corresponding declines for the NYTS were a 4.8% decline per year from 1999 to 2004 versus a decline of 3.2% per year between 2004 through 2009.

Conclusion: The decline in California student-reported exposure to smoking in cars accelerated after California enacted a smokefree car law, significantly exceeding national trends. Results may encourage other states to adopt similar laws.