Association of spatial distribution of childhood respiratory morbidity with environmental dust pollution.

The objective of this study was to investigate the spatial distribution of respiratory morbidity and asthma in children in relation to high levels of airborne dust pollution. A cross-sectional survey of 2035 children (aged 5-11 yr) by parent-completed questionnaire, with concurrent monitoring of dust deposition rates in the vicinity of children's homes, was performed in 15 primary schools (5 in each of 3 areas of Merseyside). The main outcome measures were (1) doctor-diagnosed asthma, (2) parent-reported respiratory symptoms of recent excess cough, wheeze, and breathlessness, and (3) school absenteeism due to respiratory ill health. Proximity to the source of dust pollution was associated with increased prevalence of excess cough, breathlessness, school absence due to respiratory ill health, and doctor-diagnosed asthma, after adjusting for a range of socioeconomic, environmental, and other confounding factors. The adjusted odds for excess cough and breathlessness for children living within 2 km of the source (dock area) are estimated to be almost twice those for children living more than 2 km away: excess cough 1.9 (95% CI 1.4-2.6); breathlessness 1.9 (1.3-2.7); school absence 1.5 (1.2-1.9); and doctor-diagnosed asthma 1.5 (1.1-2.0). Excess cough was significantly associated with the mean annual dust deposition recorded in the vicinity of the child's home. The adjusted odds ratio for excess cough corresponding to an increase in mean annual dust deposition of 50 mg/m2/d was 3.1 (95% CI 1.1-8.2). These results suggest that airborne dust was associated with respiratory morbidity in these children, which could relate to the high prevalence of childhood doctor-diagnosed asthma in this community.