These researchers analysed data on self-reported exposure to secondhand smoke from 3645 matched pairs of children aged 10–13 years and their parents (smokers and nonsmokers), who were participants in Keeping Kids Smokefree, a community-based study conducted in South Auckland from 2007–2009. There was approximately a 30% discordance between the self-reports of children and their parents, with parents significantly less likely than children to report smoking in homes or cars. Kappa scores for parent-child agreement by ethnicity ranged from 0.15 to 0.41 for smoking at home and 0.17 to 0.54 for smoking in cars. Results from 679 children who underwent biochemical testing for smoking exposure using exhaled carbon monoxide suggested that around 30% of children had been exposed to secondhand smoke, corroborating their self-reported proportion of 37% (baseline in the home) whereas few parents (11%) reported smoking in home or cars.
