A 3 year set of PM10 monitoring data using the tapered element oscillating
micro-balance from 3 sites in London was analysed, in conjunction with air
stream back trajectories and meteorological data for the same 24 h periods.
Geometric mean PM10 for any site against groupings of trajectory wind dire
ction (TWD) showed a south-easterly peak in PM10, Analysis of variance was
carried out using London meteorological parameters and also wind speed and
direction information calculated from positions on air mass back trajectori
es at 4 different periods prior to the approach to London. This model expla
ined 60-65% of the observed variation, and because the analysis enables the
meteorological factors to be de-coupled from the TWD, it can be concluded
that local weather is not the prime cause of the peak. It was found that fo
r 6-7% of the time when the TWD was from 120 degrees -160 degrees at least
15-20 mug m(-3) of extra PM10 was advected in. Evidence is presented that t
he local meteorology is responsible for re-suspension. By removing individu
ally each parameter retained in the model, its relative contribution to exp
laining variance was assessed. TWD, then trajectory wind speed (TWS) were f
ound to be the most important. There was a calculated reduction of 7.0 mug
m(-3) (95% confidence 6.0-8.0) of PM10 over the 1047 day monitoring period.
(C) 2001 Elsevier Science Ltd. All rights reserved.