1 Introduction |
Types of pollution
1. Air quality in the UK has improved over recent
decades but improvements are now levelling off and are increasingly
costly to achieve. A major air quality problem is being caused
by three key pollutants where the UK is failing to meet domestic
and European targets: nitrogen oxides (NOX), ozone
and particulate matter (PM).
- Nitrogen oxides (NOX)
encompasses two gasesnitrogen oxide (NO) and nitrogen dioxide
(NO2). NO reacts with other chemicals in the air to
form NO2, which is itself involved in the formation
of particulate matter.
- Ozone is a pollutant in the lower atmosphere.
It is not emitted directly from any man-made source but is formed
from chemical reactions between various air pollutants, primarily
nitrogen oxides and volatile organic compounds.
- Particulate matter (PM) is made up of tiny particles
from a variety of materials, including sulphates, nitrates, ammonia,
sodium chloride, carbon, mineral dust, and water. Particulate
matter is categorised by particle size, as either smaller than
10 microns in diameter (PM10) or smaller than 2.5 microns
Sources of pollution
2. Industry and road transport are the main sources
of air pollution, though domestic combustion and agriculture are
also to blame. Industry is a major source of emissions of NOX
(46%) and PM10 (36%). Road transport contributes to
significant emissions of NO2 (30%) and PM10
(18%). Emissions and exposure vary greatly depending on location.
Although polluting, the majority of large combustion plants are
located away from major urban centres. Road transport contributes
far more to the public's exposure to pollutants and is responsible
for up to 70% of air pollution in urban areas.
3. European and national air quality legislation
is designed to reduce risks to human health and the environment.
National emission ceilings are legally-binding, annual, total
emission caps set under the EU National Emission Ceilings Directive.
Ceilings for each Member State have been set for NOX
emissions. EU limit values are legally-binding, maximum parameters
for concentrations of pollutants over specified time periods.
These are set by the Air Quality Framework Directive and four
daughter directives for pollutants including NO2, PM10,
PM2.5. EU target values are set out in the same way
as limit values, but are not legally binding. A target value is
set for ozone.
4. The Environment Act 1995 sets national objectives
for NO2, ozone, and particulate matter that are the
same as, or in some cases more prescriptive, than corresponding
EU limit values. Air quality objectives are defined in the latest
Air Quality Strategy for England, Scotland, Wales and Northern
Ireland, published in July 2007. Environment is a devolved matter
and for some pollutants objectives are set by the administrations
in Northern Ireland, Scotland and Wales.
5. In our inquiry we set out to assess whether
the Government was developing an effective strategy for meeting
its obligations under the EU air quality directives and whether
the strategy would ensure that air pollution was reduced to acceptable
levels across the UK. In preparation for its inquiry, the Committee
commissioned a briefing on air quality from the National Audit
Office to provide an overview of the UK's performance to date
in meeting the various targets and limits for each air pollutant.
The Committee would like to thank all those who gave evidence.
We note with sadness the passing of Dr Ian McCrae who provided
a valuable contribution in this field and who appeared before
the Committee shortly before he died. We are indebted to Professor
Mike Pilling, our Specialist Adviser, for all his invaluable advice.
1 NAO, Air Quality, January 2010 Back
A list of all those who gave evidence can be found on pages 25
and 26. Back
Professor M J Pilling declared an interest on 2 February 2010,
that his son works with the Low Emissions Strategies Partnership,
who submitted written evidence to the Committee (Ev 84). Back