Smoke-free laws and secondhand smoke exposure in US non-smoking adults, 1999-2002.

Objectives: To investigate the relationship between smoke-free law coverage and secondhand smoke (SHS) exposure in the United States non-smoking adult population.

Design: We used data from the 1999-2002 National Health and Nutrition Examination Survey, a cross-sectional survey designed to monitor the health and nutritional status of the US population. Serum cotinine levels were available for 5866 non-smoking adults from 57 survey locations.