Background Secondhand smoke (SHS) represents a major preventable cause of morbidity for communities, especially for children, who are more susceptible than adults to the adverse effects of passive smoking. SHS contains several carcinogens, including benzene.

Objective To investigate the role of household characteristics and the smoking behaviours of cohabitants in predicting SHS-derived benzene exposure levels.

Methods In this cross-sectional study, 122 children (aged 5–11 years old) were selected from a school in rural Italy. Characteristics of their home environment and the smoking habits of the children's cohabitants were obtained via questionnaire, and urinary unmodified benzene (u-UB) and cotinine (a specific nicotine metabolite) levels were determined from spot urine samples.

Results Significant differences between SHS-exposed and SHS-unexposed children were found with respect to u-UB levels (median values 359.50 and 92.50 ng/litre, respectively; p<0.001). The excretion of u-UB increased significantly in parallel to increased SHS exposure as follows: unexposed to SHS (median value 92.50 ng/litre)<cohabitant(s) smoker(s) not smoking inside the home (282.00 ng/litre)<cohabitant(s) smoking inside the home only when children are out (314.50 ng/litre)<cohabitant(s) smoking inside the home even when children are in (596.00 ng/litre). The difference between groups was significant (p=0.019).

Conclusions Although smoke-free legislation has transformed the smoking behaviours of some, domestic environments remain an important source of SHS exposure for children. This fact holds true even in the case of parents and other cohabitants who believe they are fully protecting children by smoking only outdoors or at home only when the children are not present. These findings should be included in Italian community-level health promotion interventions for discouraging tobacco use.