PRONOUNCED DECREASE OF PCDD PCDF BURDEN IN AMBIENT AIR/

Concentrations (annual means) of PCDD/PCDF in the ambient air of four cities in North-Rhine-Westfalia (NRW, Germany) were measured at the sa me locations in 1987/88 [1] and again in 1993/94. During this time per iod, the annual averages of the PCDD/PCDF concentrations decreased fro m 130 to 40 fg I-TE/m(3) in Koln (69%), from 332 to 124 fg I-TE/m(3) i n Duisburg (63%), from 204 to 76 fg I-TE/m(3) in Essen (63%) and from 224 to 120 fg I-TE/m(3) in Dortmund (46%). This decrease can be relate d to abatement actions taken since 1989. In the measurement campaign o f 1993/94, polychlorinated biphenyls (PCB) were measured simultaneousl y with the PCDD/PCDF. At urban locations the annual averages of PCB (t otal of trichloro- to decachlorobiphenyl) in urban air ranged between one and two ng/m(3) and in rural areas between 0.1 and 0.3 ng/m(3). (C ) 1997 Elsevier Science Ltd.