Outdoor air pollution and children's respiratory symptoms in the steel cities of New South Wales

Objective To investigate the relationship between outdoor air pollution and the respiratory health of children aged 8 to 10 years. Design A cross‐sectional survey (between October 1993 and December 1993) of children's health and home environment. Summary measures of particulate pollution (levels of particles with an aerodynamic diameter less than 10μm [PM10] each 6th day) and SO2 (daily mean and maximum hourly values) were estimated for each area (using air quality monitoring station data from July 1993 to June 1994). Setting and survey participants Parents of 3023 primary school children (Years 3, 4 and 5) from industrial and non‐industrial areas with air quality monitoring stations in the Hunter and Illawarra regions of New South Wales. Main outcome measures Reported occurrence of four or more chest colds, four or more attacks of wheezing, and night‐time cough without a cold for more than two weeks, all within the previous 12 months. Results 77% response rate, ranging by area from 66% to 88%. The average annual outdoor air pollution for the nine areas was 18.6–43.7 μg/m3 for PM10 and 0.16–0.90 parts per hundred million for SO2. The proportion of children reported to have the main outcome symptoms were: chest colds, 3.0%–9.7%; night cough, 12.3%–30.5%; and wheeze, 3.4%–11.3%. There was no significant association with SO2, but a significant increase in the odds of symptoms per 10 μg/m3 increase in PM10 on chest colds (odds ratio [OR], 1.43; 95% confidence interval [Cl], 1.12–1.82) and night‐time cough (OR, 1.34; 95% Cl, 1.19–1.53), but not wheeze. Passive smoking was significantly associated with chest colds but not with the other symptoms. Maternal allergy was associated with all three respiratory symptoms, most strongly with wheeze. Conclusion These results provide evidence of health effects at lower than expected levels of outdoor air pollution in the Australian setting. They also suggest differences in contributions of environmental and hereditary factors to cough and chest colds compared with wheeze.