Association of outdoor air pollution and indoor renovation with early childhood ear infection in China

Abstract

Background: Otitis media (OM) is a common infection in early childhood with repeated attacks that lead to long-term complications and sequelae, but its risk factors still remain unclear.

Objective: To examine the risk of childhood OM for different indoor and outdoor air pollutants during different timing windows, with a purpose to identify critical windows of exposure and key components of air pollution in the development of OM.

Methods: We conducted a retrospective cohort study of 1617 children aged 3-4 years in Changsha, China (2011-2012). Children's life-time prevalence of OM and exposure to indoor air pollution related to home renovation activities were surveyed by a questionnaire administered by the parents. Children's exposure to outdoor air pollution, including nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and particulate matter with an aerodynamic diameter ≤ 10 μm (PM₁₀), was estimated using the measured concentrations at municipal monitoring stations. The odds ratio (OR) and 95% confidence interval (CI) of childhood OM for prenatal and postnatal exposure to indoor and outdoor air pollution were examined by using logistic regression model.

Results: Life-time prevalence of OM in preschool children (7.3%) was associated not only with prenatal exposure to industrial air pollutant with adjusted OR (95% CI) = 1.44 (1.09-1.88) for a 27 μg/m³ increase in SO₂ but also with postnatal exposure to indoor renovations with OR (95% CI) = 1.62 (1.05-2.49) for new furniture and 1.81 (1.12-2.91) for redecoration, particularly in girls. Combined exposure to outdoor SO₂ and indoor renovation significantly increased OM risk. Furthermore, we found that exposure to outdoor SO₂ and indoor renovation were significantly associated with the onset but not repeated attacks of OM.

Conclusion: Prenatal exposure to outdoor industrial air pollution and postnatal exposure to indoor renovation are independently associated with early childhood OM in China and may cause the OM onset.

Keywords: Ambient air pollution; Home renovation; Indoor air pollution; Otitis media; Postnatal; Prenatal.