No abstract

In September 1995, ambient air concentrations of poh chlorinated dibenzo-/?-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) were measured at five locations in Montgomery County, Ohio. Montgomery County is an industrialized urban area with two known and many other potential sources of PCDD/PCDF. The known sources are the north and south municipal waste incinerators operated by the county government. Stack emissions tests in 1988Stack emissions tests in , 1994Stack emissions tests in , and 1995 showed that PCDD/PCDF emissions increase dramatically with electrostatic precipitator (ESP) temperature, particularly above 230°C. After the 1994 tests, incinerator improvements to maintain ESP temperatures below 230°C were completed. Ambient air 24-h total mass PCDD/PCDF concentrations measured in 1995 ranged from 1.2 pg/m3 (rural location) to 29.7 pg/m3 (Edgemont neighborhood in the city of Dayton). Meteorological conditions, operational data, and chemical mass balance modeling suggest that a Polyvinylchloride (PVC) pyrolyzer, and not the municipal waste incinerators, may be the principal source of ambient air PCDD/PCDF concentrations in Montgomery County.