The prevalence of self-reported secondhand smoke (SHS) exposure at home and changes in any exposure, as measured by serum cotinine (a biologic indicator of recent SHS exposure), declined significantly in nonsmoking children, adolescents, and adults in recent years.

The MMWR analysis used data from the National Health and Nutrition Examination Surveys to determine at-home SHS exposure and serum cotinine levels in nonsmokers aged 4 years and older, from 1988-1994 and from 1999-2004. The percentage of U.S. nonsmokers who reported SHS exposure at home declined from 20.9 percent to 10.2 percent between the two time periods. Similarly, the percent of nonsmokers with any exposure to SHS declined significantly, from 83.9 percent to 46.4 percent.

However, between 1999 and 2004, children and adolescents remained at higher risk of SHS exposure than adults, with nearly one in four children aged 4 to 11 and one in five adolescents aged 12 to 19 exposed to SHS in the home, compared with only one in twenty adults aged 20 years or older. Non-Hispanic blacks and low-income Americans were also at significantly higher risk of SHS exposure.

This is attributed to the broad declines in SHS exposure to laws and policies that restrict or eliminate smoking in workplaces and public places, the increased percentage of households that have rules against smoking in the home, and the declining prevalence of smoking among Americans.