Air quality expert group - Fine particulate matter (PM2.5) in ... - Defra

3.7.3 Bonfires and fireworks
Concentrations and composition of PM2.5
30 Episodes of elevated PM2.5 concentrations are clearly associated with emissions
from bonfires and/or fireworks, as is evident in the peaks lasting for several
hours that frequently occur around Bonfire night (see the example shown in
Figure 3.16). The concentrations at these four London sites rose sharply on the
Saturday evening, 7 November 2010, before declining more slowly. Although
Bonfire night was the day before, there was only a small peak on the Friday
evening. The wind speed was very low on the Saturday night but stronger
on the Friday, showing the importance of local meteorological conditions in
determining whether an episode will occur. Separate analysis (not shown)
revealed that the peaks were almost entirely PM2.5, with very little PM2.5-10.
Also, concentrations of NOx rose at the same time as the PM2.5, but there
was no impact on NO2 concentrations, which is evidence of fresh NOx
emissions. Such episodes can contribute around 0.1 µg m -3 to the annual
mean concentration. PM2.5 episodes due to bonfires and fireworks are
of short duration and will only have a small effect on annual mean
concentrations.
PM2.5
300
200
100
Nov 04
Nov 05 Nov 06 Nov 07
London N. Kensington London Bloomsbury
London N. Kensington London Bloomsbury
Nov 04 Nov 05 Nov 06 Nov 07
Figure 3.16: PM2.5 concentrations (µg m -3 ) over four days in November 2010 at
four London sites. The date markers are for midnight.
300
200
100
65