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

70. Annual average concentrations of PM2.5 over Greater London are shown in
Figure 5.3 (Chapter 5), with the levels of the scale chosen in relation to the limit
values and reduction targets stipulated in the European Air Quality Directive
(2008/50/EC). Specifically, they correspond to the limit value for 2015 (25 µg
m -3 ), the indicative limit value for 2020 (20 µg m -3 ) and levels corresponding to
the different exposure reduction targets (18-22 µg m -3 for 20%, 13-18 µg m -3
for 15% and 8.5-13 µg m -3 for 10%). Areas and percentage areas within each
of the exposure bands, and corresponding to exceedence of the limit values, are
shown in Table A2.10.1. It is noted that background concentrations are mainly
below 13 µg m -3 whilst values at a number of hot spots in central London are
above 20 µg m -3 .
Table A2.10.1: Areas of exceedences for London for a range of PM2.5 bandings
for the calculated annual average concentration for 2008.
PM2.5 banding (µg m -3 ) Area (km 2 ) % of total modelled area
>25 0.015 0.0005%
>20 0.504 0.0158%
>22 0.125 0.0039%
18-22 2.277 0.071%
13-18 125.71 3.933%
8.5-13 3068.4 95.993%