Emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) by municipal solid waste (MSW) incinerators cause concern to the populations living in the vicinity of these facilities. In this study, the health risks of PCDD/F exposure were assessed for adults and children living 500 and 1,000 m from the MSW incinerator. A comparative analysis was performed before (1998) and after (2000) pronounced decreases in PCDD/F air emissions from the stack were noted as a consequence of technical improvements in the facility. At 500 m, total environmental exposure to PCDD/Fs diminished from 5.102 x 10(-5) to 1.271 x 10(-5) ng I-TEQ/kg/day for adults, and from 8.131 x 10(-5) to 2.656 x 10(-5) ng I-TEQ/kg/day for children, which means a reduction of 75.1% for adults and 67.3% for children between 1998 and 2000. At 1,000 m, total environmental PCDD/F exposure diminished from 4.087 x 10(-5) ng I-TEQ/kg/day in 1998 to 0.995 x 10(-5) ng I-TEQ/kg/day in 2000 and from 6.294 x 10(-5) ng I-TEQ/kg/day in 1998 to 1.983 x 10(-5) ng I-TEQ/kg/day in 2000 for adults and children, respectively. However, these reductions are almost imperceptible compared with the contribution of dietary intake of PCDD/F to total exposure to these contaminants. The present results corroborate that for MSW incinerators with modern technologies, human PCDD/F exposure is mainly due to background contamination.