Children's residential exposure to environmental tobacco smoke varies greatly between the Nordic countries.

Objective: To assess similarities and differences in the Nordic countries regarding ETS (environmental tobacco smoke) exposure in young children.

Design: A population-based cross-sectional study comprising a randomly selected sample of 5,500 households which included a child born in 1992. Data were collected using a mailed anonymous questionnaire.

Results: While the prevalence of household smoking was similar in all countries, there was a great difference between the countries with regard to child ETS exposure. Finnish parents were more likely than all other Nordic parents to protect their children from ETS and the situation was worst in Denmark and Iceland, where almost half of all households, and nine out of ten households containing daily smokers, exposed their children. Approximately eight out of ten current and former smokers in all countries stated that they had made efforts to change their smoking habits because of their children.