PCBS AND PAHS IN UK URBAN AIR

As part of a long term air monitoring programme the ambient air in fou r UK urban areas was sampled throughout 1991. Polychlorinated biphenyl s (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were sampled from the air in London, Cardiff, Manchester and Stevenage. Both vapour and particulate phases were collected at each site, and total concentrati ons are reported for 26 alternate weeks of the year. Total PAH concent rations (sum of 15 compounds) varied between 11 and 735 ng/m3 for the four sites. For each site PAH levels were dominated by the lower molec ular weight compounds of phenanthrene, fluorene and pyrene, which made up more than 75% of the SIGMAPAH. The contribution of individual comp ounds to the total was broadly similar at each site in both the winter and summer. Concentrations of the higher molecular weight compounds w ere greater by a factor of 2.5 in the winter months. Eight PCB congene rs (28, 52, 77, 101, 118, 138, 153 and 180) were measured at each site . London gave the highest recorded value of 3.85 ng SIGMAPCB/m3. Value s at the four sites ranged between 0.19-3.85 ng/m3, this range being s imilar to levels reported in other European and American cities. Conge ners 28 and 52 dominated the air mixture, comprising > 80% of the meas ured total. PCB concentrations in the summer were, on average, double those for the winter.