Evaluation of TEOM (TM) 'correction factors' for assessing the EU Stage 1 limit values for PM10

A study has been carried out to compare the results of PM10 determinations using TEOM(TM) and gravimetric instruments. Whilst the TEOM instruments hav e been used by the UK Government for many years to develop a National Air Q uality Objective, the European Directive (99/30/EC) Stage 1 limit values fo r PM10 require a gravimetric method (or an approved equivalent method) to b e used. However, there are significant differences between the two techniqu es, which have been investigated by co-locating a TEOM PM10 monitor and a g ravimetric (Partisol) PM10 sampler at Marylebone Road, London between June 1997 and January 2000. This paper investigates the current practice of usin g a single 'correction factor' on TEOM PM10 data when these data are being used to assess the EU Stage 1 limit values for PM10, which should be measur ed using a gravimetric technique. The ability of the 'corrected' TEOM PM10 values to accurately reflect the annual mean and the number of 24 h means a bove 50 mug m(-3) produced by the co-located Partisol PM10 sampler is used as the test for the suitability of the single correction factor. This study demonstrates that a single 'correction factor' will not reflect the site a nd season specificity. (C) 2001 Elsevier Science Ltd. All rights reserved.