To assess the effects of air pollution associated with coal heating in winter on pulmonary function of school children, pulmonary function tests (FVC, FEV(1.0), PEF, FEF(75)) of 332 children in Shenyang, located in the northeast of China, were done four times between October 2001 and June 2002. The collected airborne particulate matter (PM) was analyzed for the concentrations of total suspended particles (TSP), PM of less than 7 microm in aerodynamic diameter (PM(7)), and PM of less than 2.1 microm (PM(2.1)). All four pulmonary function tests were completed in 244 school children. The airborne PM concentration was higher in April 2002 (end of heating) than in October 2001 (prior to heating). All four pulmonary function indices, adjusted for age and height, were significantly lower in April 2002 than in October 2001; the FEV(1.0) was lower in boys (0.233l, 95% CI: 0.167-0.299l) and girls (0.222l, 95% CI: 0.165-0.280l). The decrease continued to be significant in June 2002 compared to October 2001. The decreases in FEV and FEV(1.0) were also significantly associated with airborne PM concentration, which had a delayed effect on pulmonary function. An increase from the 25th to the 75th percentile of TSP, PM(7) and PM(2.1) was associated with a delayed decrease in FEV(1.0); 0.059l (95% CI: 0.020-0.106l), 0.095l (95% CI: 0.057-0.139l) and 0.110l (95% CI: 0.072-0.147l) in boys, and 0.066l (95% CI: 0.026-0.106l), 0.101l (95% CI: 0.063-0.139l) and 0.114l (95% CI: 0.080-0.152l) in girls, respectively. Our findings show that airborne PM might have a subacute effect on pulmonary function in children in Shenyang, and that PM(7) and PM(2.1) have more adverse effects on pulmonary function than TSP. The effects of airborne PM appear to be prolonged.