with domestic and industrial combustion, with
coal burning leading to high concentrations of
smoke and sulfur dioxide. A recent retrospective
analysis has indicated that the most famous example of this type of pollution – the great London
smog of 1952 – was responsible for 12,000 deaths
[1]. However, during the 1940s and 1950s an
altogether different type of pollution was observed
in the United States. Haagen-Smit identified a
mechanism by which air pollutants reacted with
the Los Angeles sunlight to produce a noxious
photochemical smog [2], and it became clear that
the pollution originated not from the use of coal
but from road vehicles.
In the subsequent decades urban air pollution
has become synonymous with road transport, the
link being attributable primarily to the growth in
the ownership and use of private cars. Photochemical smog has remained a problem in some of the
largest cities in the world, and many people are
exposed to pollutant concentrations which exceed
health-based air quality standards. It has also
become evident that some transport-derived pollutants can travel thousands of kilometers before
deposition and damage occur and, in the case of
greenhouse gases, can have a global effect over
long timescales. If transport systems are to become
environmentally sustainable, then the scale of such
adverse effects will have to be greatly reduced.
The aim of this entry is to provide an overview
of the impacts of surface transport (road, rail, and
shipping) on emissions and air quality. Different
regions of the world have different air pollution
problems, and not all countries and issues can be
covered here. The entry refers mainly, but not
exclusively, to the European Union (EU), and
the emphasis is on local air pollution in populated
areas. Inevitably, the entry deals predominantly
with road transport, but some consideration is
also given to the other modes.
Introduction
Surface transport is an important, and in many
respects, the most important source of air pollution. The pollutants released from road, rail, and
waterborne traffic are implicated in a variety of
direct and indirect detrimental impacts on amenity,
health, ecosystems, and cultural heritage over different time periods and on different geographical
scales. The effects of transport pollution can be
very local and immediate, such as the nuisance
caused by a plume of black smoke from the
exhaust pipe of a car or a diesel train. More seriously, repeated exposure to exhaust gases and
particles is linked to aggravated respiratory and
cardiovascular disease, changes to lung tissue,
changes in the function of the nervous system,
and premature mortality [3, 4]. Threats to cultural
heritage posed by atmospheric pollutants include
the soiling of historical buildings – a common
sight alongside busy urban roads – and indoor
damage to works of art and museum exhibits.
Transport emissions also contribute to the regional
degradation of air quality, to eutrophication, and to
acidification (see Chapter, ▶ “Regional Air Quality”). Moreover, stable pollutants, including the
greenhouse gases carbon dioxide (CO 2 ), methane,
and nitrous oxide can contribute to environmental
problems on a global scale for decades and even
centuries.
The pollutants that are currently causing the
greatest concern in terms of air quality, primarily
because of their impact on human health, are airborne particulate matter (PM), nitrogen dioxide
(NO 2 ), and ground-level ozone (O 3 ). Surface
transport is an important contributor to all three
[5], but road transport is the main culprit, especially in population centers, and it presents some of
the greatest challenges in terms of sustainability.
The importance of road transport as a source of
pollution can be illustrated by reference to sectoral
emissions in Europe. Figure 1 shows emission
data for the EU-27 countries, based on submissions to the UNECE Convention on Long-range
Transboundary Air Pollution (CLRTAP). In 2008,
road transport was the largest contributor to NO x
emissions in Europe (41%), and was also a major
contributor to PM 10 emissions. By comparison,
non-road transport was responsible for just 7% of
total NO x emissions and only 2% of total PM 10
emissions. However, it is important to observe
that the totals in Fig. 1 are based on national
reporting, and do not include international aviation or international maritime shipping. The latter
48
Air Quality, Surface Transportation Impacts on
coal burning leading to high concentrations of
smoke and sulfur dioxide. A recent retrospective
analysis has indicated that the most famous example of this type of pollution – the great London
smog of 1952 – was responsible for 12,000 deaths
[1]. However, during the 1940s and 1950s an
altogether different type of pollution was observed
in the United States. Haagen-Smit identified a
mechanism by which air pollutants reacted with
the Los Angeles sunlight to produce a noxious
photochemical smog [2], and it became clear that
the pollution originated not from the use of coal
but from road vehicles.
In the subsequent decades urban air pollution
has become synonymous with road transport, the
link being attributable primarily to the growth in
the ownership and use of private cars. Photochemical smog has remained a problem in some of the
largest cities in the world, and many people are
exposed to pollutant concentrations which exceed
health-based air quality standards. It has also
become evident that some transport-derived pollutants can travel thousands of kilometers before
deposition and damage occur and, in the case of
greenhouse gases, can have a global effect over
long timescales. If transport systems are to become
environmentally sustainable, then the scale of such
adverse effects will have to be greatly reduced.
The aim of this entry is to provide an overview
of the impacts of surface transport (road, rail, and
shipping) on emissions and air quality. Different
regions of the world have different air pollution
problems, and not all countries and issues can be
covered here. The entry refers mainly, but not
exclusively, to the European Union (EU), and
the emphasis is on local air pollution in populated
areas. Inevitably, the entry deals predominantly
with road transport, but some consideration is
also given to the other modes.
Introduction
Surface transport is an important, and in many
respects, the most important source of air pollution. The pollutants released from road, rail, and
waterborne traffic are implicated in a variety of
direct and indirect detrimental impacts on amenity,
health, ecosystems, and cultural heritage over different time periods and on different geographical
scales. The effects of transport pollution can be
very local and immediate, such as the nuisance
caused by a plume of black smoke from the
exhaust pipe of a car or a diesel train. More seriously, repeated exposure to exhaust gases and
particles is linked to aggravated respiratory and
cardiovascular disease, changes to lung tissue,
changes in the function of the nervous system,
and premature mortality [3, 4]. Threats to cultural
heritage posed by atmospheric pollutants include
the soiling of historical buildings – a common
sight alongside busy urban roads – and indoor
damage to works of art and museum exhibits.
Transport emissions also contribute to the regional
degradation of air quality, to eutrophication, and to
acidification (see Chapter, ▶ “Regional Air Quality”). Moreover, stable pollutants, including the
greenhouse gases carbon dioxide (CO 2 ), methane,
and nitrous oxide can contribute to environmental
problems on a global scale for decades and even
centuries.
The pollutants that are currently causing the
greatest concern in terms of air quality, primarily
because of their impact on human health, are airborne particulate matter (PM), nitrogen dioxide
(NO 2 ), and ground-level ozone (O 3 ). Surface
transport is an important contributor to all three
[5], but road transport is the main culprit, especially in population centers, and it presents some of
the greatest challenges in terms of sustainability.
The importance of road transport as a source of
pollution can be illustrated by reference to sectoral
emissions in Europe. Figure 1 shows emission
data for the EU-27 countries, based on submissions to the UNECE Convention on Long-range
Transboundary Air Pollution (CLRTAP). In 2008,
road transport was the largest contributor to NO x
emissions in Europe (41%), and was also a major
contributor to PM 10 emissions. By comparison,
non-road transport was responsible for just 7% of
total NO x emissions and only 2% of total PM 10
emissions. However, it is important to observe
that the totals in Fig. 1 are based on national
reporting, and do not include international aviation or international maritime shipping. The latter
48
Air Quality, Surface Transportation Impacts on