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

PM2.5 in the UK
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14. The London Low Emission Zone (LEZ) was specifically introduced as a policy
to reduce PM emissions from traffic in London. Since 2008, the LEZ requires
heavy goods vehicles (HGVs) and buses in much of Greater London to meet a
minimum of Euro III standards for PM; the requirement was strengthened to
Euro IV in January 2012. The LEZ scheme will also be extended to large vans and
minibuses which will be required to meet a minimum of Euro III standards for
PM from January 2012. Transport for London (TfL) is also introducing hybrid and
hydrogen fuel cell vehicles to its bus fleet which will help to reduce PM exhaust
emissions.
15. Mitigation of non-exhaust emissions from vehicles is far more difficult. TfL is
carrying out a trial of new power washing and dust suppressant technology as a
means of reducing PM emissions from road dust resuspension. The roads in two
locations will be jet-washed to remove existing particles, then sprayed with a
biodegradable solution to stick particles to the road.
16. Further details on legislation and abatement measures for controlling PM
emissions are given in AQEG (2005) and a recent SNIFFER report (SNIFFER,
2010). Although introduced to control total PM mass emissions, all of these
measures are assumed to reduce emissions of the PM2.5 fraction in inventories.
17. Emissions of PM2.5 in the UK projected forward to 2020 are estimated by
making assumptions about future levels of activities and changes in emission
factors (Wagner, 2010). For stationary sources, consideration is given to the
implementation of emissions legislation, new technologies and fuel switching
in combustion (e.g. in power stations, domestic heating and in industry),
as well as to the latest UK energy projections for industrial, commercial,
domestic, agricultural and power generating industries. For mobile sources,
the penetration of new vehicles meeting tighter emission regulations (up to
Euro VI for light duty vehicles and Euro VI for heavy duty vehicles) is taken into
account, together with figures from DfT on future traffic projections and other
assumptions affecting the fleet in the future. The projections also account for
the uptake of biofuels reaching 10% of transport fuels by energy content by
2020 in accordance with the conditional target in the EU Biofuels Directive
(2003/30/EC). Consumption of low-strength blends of bioethanol and biodiesel
lead to a reduction in exhaust emissions of PM (AQEG, 2011). New regulations
on PM emissions from non-road mobile machinery are also taken into account.
18. Figure 4.1 shows the trends in primary PM2.5 emissions from sources in the UK
between 1990 and 2020. The figures are taken from the latest version of the
NAEI covering the years up to 2009 (Passant et al., 2011) and projections up
to 2020 based on the Department of Energy and Climate Change’s (DECC’s)
UEP38 energy projections and DfT’s AF09 traffic projections. The figures are also
presented in Table 4.1.
19. Total UK emissions of PM2.5 in 2009 amounted to 70 ktonnes. The inventory
covers around 165 individual sources with many of these making similar
contributions to the UK totals. These sources have been combined into key
groups in Figure 4.1. When grouped in this way, the single largest source
of PM2.5 emissions in 2009 was road transport exhausts (18%) followed by
residential combustion (14%) and non-exhaust emissions from tyre and brake
wear, and road abrasion (11%). This indicates that the combined contribution
of road transport sources was 29%.