This study updates previous estimates of emissions to the UK atmosphere of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Following a systematic screening of a range of industrial processes operating in the UK for the potential to release PCDD/Fs to atmosphere, 23 industrial processes were shortlisted for further consideration as potential emitters. To these processes were added six non-industrial sources of PCDD/F emissions; domestic coal and wood combustion, crematoria, traffic, natural fires and accidental fires. For each shortlisted process emission factors were identified. Emission factors were combined with the quantity of material treated or produced to generate an estimate of the annual quantity of PCDD/Fs released to atmosphere. The total estimated current emissions to atmosphere ranged from 560 to 1100 g I-TEQ year(-1), with industrial processes contributing 535-955 g I-TEQ year(-1), an average of approximately 90% of the total inventory. Emissions from MSW incineration plants were dominant, contributing an average of 70% to the total emissions from industrial sources. Emissions from coal combustion, sinter plants, iron and steel plants, non-ferrous metals operations and incineration of clinical waste collectively contributed an average of 25% to total industrial emissions in roughly equal proportions. The effect of tightening emission controls was also examined. Assuming a situation when current regulations concerning PCDD/F emissions are fully implemented, a reduction in emissions from 560-1100 g I-TEQ year(-1) to 110-350 g I-TEQ year(-1) is envisaged. The largest reduction is effected through the imposition of a 1 ng I-TEQ m(-3) emission limit on MSW and clinical waste incinerators: the contribution from these sources falls from the present range of 60-85% to approximately 6-18% of total emissions.
