EFFECT OF COMBUSTION TEMPERATURE ON THE ATMOSPHERIC STABILITY OF POLYBROMINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS

Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDDs and PBDFs) produced from the combustion of polyurethane foam (PUF) containing 4.4% polybrominated diphenyl ethers (PBDPEs) were injected into outdoor Teflon film chambers and aged in the presence of sunlight under typical atmospheric conditions. Experiments with combustion temperatures in the range of 400-470-degrees-C were categorized as ''low-temperature'' experiments and those in the range of 670-780-degrees-C as ''high-temperature'' experiments. Production of PBDFs, namely, tetrabrominated dibenzofuran (TBDF), and pentabrominated dibenzofuran (PeBDF) and decay of tetrabrominated-p-dioxin (TBDD) were observed in low-temperature experiments. Production of TBDF and PeBDF is believed to occur from the photolysis of unburned PBDPEs. TBDF, PeBDF, and TBDD emissions from high-temperature experiments were stable. Particle-bound PAHs from low-temperature experiments degraded while corresponding PAHS from high-temperature experiments were stable. Experimental observations suggest that under incinerator conditions at combustion temperatures of 800-degrees-C, particulate-bound emissions of PBDDs, PBDFs, and PAHs will be transported over long distances due to long half-lives. Combustion temperatures around 450-degrees-C can lead to unstable emissions of these compounds with atmospheric half-lives of the order of 1-6 h.