ENVIRONMENTAL RISK FACTORS WITH POTENTIALS FOR INFLUENCING THE OCCURRENCE OF ASTHMA AMONG CHILDREN IN IBADAN, NIGERIA

Abstract

The prevalence of asthma has increased in recent years. Although most asthma studies in Nigeria focused on the burden of the disease among children, the risk factors that may favour its occurrence have not been well investigated. This study was therefore designed to determine the environmental factors which have potential for precipitating the occurrence of asthma among children in lbadan. A case-control study design was employed with 32 asthmatic children serving as cases and 32 non- asthmatic children but with non- life threatening health conditions constituting the Controls. The study participants aged 4-15 years were consecutively selected from the patients attending the children outpatient clinic of the University College Hospital and Oni Memorial Children Hospital, Ibadan from January-July, 2008. A validated questionnaire was used to collect data from their parents. The participants and their parents were traced to their homes where both indoor and outdoor environmental monitoring was done using dust track for Particulate Matter (PM) and digital gas meter for Carbon-monoxide (CO), Nitrogen-dioxide (NO₂) and Sulphur-dioxide (SO₂). Data were analysed using descriptive statistics, Chi-square and Mann Whitney U tests. The results were compared with the National Guideline Limit (NGL). The mean ages of the cases and controls were 8.9±3.6 years and 8.8±3.2 years respectively. There were more male cases (62.5%) and controls (75.0%). Significantly more cases (56.3%) had a family history of asthma compared with the controls (15.6%) (p<0.05). The prevalence rates of parental smoking among cases and controls were 12.5% and 6.3% respectively. Parents' rates of reporting mold growth on the walls of their houses among cases and controls were 40.6% and 34.4% respectively. A higher proportion of the houses of the cases (40.6%) compared with the controls (21.9%) were near industries. More cases (34.4%) had pets in their houses than the controls (25.0%). Significantly more cases (87.5%) compared with the control (21.9%) reported allergic reaction to dust (p<0.05). Episodes of asthma were significantly higher during the rainy season (65.6%) than the dry season (9.4%) (p<0.05). There was no significant difference in the median concentration of indoor CO in the living room of the cases (0.2ppm) (range: 0.04ppm -0.67ppm) compered with the controls (0.2ppm) (range: 0.03ppm-0.3ppm). The median concentration of indoor NO₂ in the cases' kitchen was 0.02ppm (range: 0.001 ppm to 0.2ppm) compared with 0.01ppm among the controls (range: 0.01 ppm to 0.04ppm).The median concentration of the outdoor particulate matter among the cases was 28.75ug/m³) (range: 0.14ug/m³ - 186.70 ug/m³) compared with the controls (34.7 ug/m³) (range: 10.6 ug/m³-360.2 ug/m³ and difference was statistically significant. The median concentration for PM, CO and NO₂ among the cases and controls were PM (Cases-28.75ug/m³; Controls-34.7 ug/m³), CO (Cases- 0.2 ppm; Controls- 0.2ppm), NO₂ (Cs-0.02ppm; Ct- 0.01ppm) and these fell within the NGL of 250 ug/m³, 10ppm and 0.04-0.06ppm respectively. Smoking cigarettes, dust and rainy conditions were the main environmental factor, that were linked with asthma in children. Public enlightenment interventions are needed to sensitise parents about these risk factors.