Concentrations of indoor gaseous air pollutants and risk factors associated with childhood asthma in Benin City, Nigeria

Pollutants from various indoor sources account for indoor air pollution mostly in developing countries and pose health risks to children. This study assessed the levels of indoor gaseous pollutants and environmental risk factors associated with asthma in children. A cross-sectional household survey was conducted among 304 children between the ages of 1 and 17 years. Indoor pollution at home was investigated using a modified international survey on asthma and allergies in childhood (ISAAC) questionnaire. Concentrations of indoor gaseous pollutants (CO, SO2 and NO2) were measured in two hundred and twenty-five randomly selected households using a MultiRae lite gas meter. The data obtained were analysed using SPSS for windows version 21.0. The risk factors for childhood asthma were obtained as odds ratios (ORs) using multivariate logistic regression. Mean concentrations of indoor gaseous pollutants ranged between 2.34-3.14 and 2.21-2.61 mg/m(3) (CO), 0.02-0.05 and < 0.002-0.03 mg/m(3) (NO2) and < 0.002-0.03 and < 0.002-0.02 mg/m(3) (SO2) in the wet and dry seasons. The mean values of pollutants were within the WHO permissible limits. The morbidity rates of clinical asthma, physician-diagnosed asthma and recurrent wheeze in the past 12 months among the respondents were 5.6%, 2.6% and 11.8% respectively. There was no association between asthma prevalence and air pollutant exposures except with CO (R = 0.130). However, the number of occupants, family history of asthma, current smoking, use of kerosene and proximity of residence to the highway with significant (p < 0.05) odds ratios (12.4, 3.51, 2.51, 7.20 and 3.46) were independent contributors to current asthma in children. The study showed that exposure to household risk factors contributed to increased asthma among children in the study locations.