Ambient monitoring of benzo-a-pyrene (B[a]P) emissions at two oil refineries.

This report describes work undertaken by the National Physical Laboratory, for the Energy Institute’s Air Emissions Group, to monitor boundary-fence concentrations of particulate phase benzo-[a]-pyrene (B[a]P) at two oil refineries in the UK. Monitoring took place at Refinery A in early November 2004, and at Refinery B in late November/ early December 2004. NPL acquired five pairs of samples at each refinery; each sample pair consisting of samples taken at nominally upwind and downwind locations of the potential PAH sources at each refinery. Additionally, three pairs of vapour phase samples were acquired at each refinery. Analysis of these samples revealed that there was no significant difference between the (particulate or vapour phase) B[a]P concentrations at the upwind and downwind sampling locations. In addition, the B[a]P concentrations measured at the refineries were comparable to the concentrations expected at urban sampling locations around the UK PAH Network during November and December. The average measured concentrations at the refineries were well below the target value stated for PAHs in the European Commission’s Fourth Air Quality Daughter Directive.