Socioeconomic patterns in indoor environment in Denmark: cross-sectional studies from 2000 and 2021

To examine changes and socioeconomic patterns in indicators of a poor indoor environment in 2000 and 2021.

Cross-sectional data from the Danish Health and Morbidity Survey in 2000 and 2021.

The study included 27,068 participants. Indicators of indoor environment (annoyances from mould, temperature, draught, traffic and neighbour noise, and presence of water damage) were obtained from questionnaires (2021) and partly by interview (2000). Socioeconomic status included home ownership, educational level, and household income. The degree of social inequality in the indoor environment was estimated using the concentration index of inequality.

The prevalence of annoyances due to draught, temperature, and noise increased significantly from 2000 to 2021 (e.g., temperature 5.9%-25.1%, odds ratio (OR) 6.72, 95% confidence interval (CI) 6.12-7.38), whereas the prevalence of water damage decreased (17.7%-13.8%, OR 0.85, 95% CI 0.76-0.96). No difference was seen in annoyances due to mould (3.1% in 2000 and 2.5% in 2021, OR 0.90, 95% CI 0.69-1.17). Social inequality was present for thermal conditions, annoyances due to noise and presence of water damage when assessed by income but not by educational level. Conditions were more prevalent among individuals with low income in both 2000 and 2021.

The proportion of individuals reporting a poor indoor environment due to thermal conditions and noise increased in the period 2000-2021. Social inequality was observed in all indicators of a poor indoor environment for household income, whereas the inequality was less pronounced when assessed by educational level.