The aim of this study was to analyse associations between crowded housing and children’s indoor living environment, respiratory and allergic disorders and general health.

A cross-sectional study.

Sweden, using data from the Swedish National Environmental Health Survey 2019.

The study sample included 48 512 children (aged 6–10 months, 4 years and 12 years). We also investigated associations in vulnerable subgroups, such as children with asthma and those living under unfavourable socioeconomic conditions.

Primary outcomes in the living environment were at least one sign of mould, poor indoor air quality, unpleasant odours, too warm indoors in summer and too cold indoors in winter. Primary outcomes for children’s health were asthma, airway problems, breathing difficulties, rhinitis symptoms, mould and mites allergy, pollen allergy, furred pet allergy and good general health.

About one in five children lived in an overcrowded home. Factors from the indoor living environment such as perceived poor indoor air quality and mould were significantly associated with crowded housing. Moreover, children who lived in overcrowded conditions were less likely to report good general health than children in non-crowded households (OR 0.64, 95% CI 0.54 to 0.76). This association was even stronger in children with asthma (OR 0.51, 95% CI 0.34 to 0.77). Few significant associations were, however, observed with the respiratory and allergic health outcomes.

Crowded housing is associated both with a poor indoor environment and with poorer general health in children. Children with asthma may experience even poorer general health.