Climate in cities
Basics
Unit 1:
Air pollution due to human activity
Air pollution is a serious problem in cities. It changes our urban climate,
degrades the environment and has negative impacts on the economy and on
our health. Industry and transport are the largest sources of air pollutants and
emission of these pollutants results in high levels of particles and soot in the air
and can cause smog to form.
Industrial accidents can cause huge inputs of air pollutants into the atmosphere
and these emissions may lead to permanent degradation of the natural
environment. One of the most polluted regions in Europe is the so called "Black
Triangle", located at the junction of the borders of Germany, Poland and The
Czech Republic, where huge brown coal resources are exploited.
As the atmosphere is constantly moving, pollutants are carried great distances
away from their source region. This means that air pollution is an international
rather than local problem.
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Part 1: What is it?
Air pollutants can be either gases or aerosols (particles or liquid
droplets suspended in the air). They change the natural composition of
the atmosphere, can be harmful to humans and other living species and
can cause damage to natural water bodies and the land.
Clean air is made up of naturally occurring
chemicals. Oxygen and nitrogen make up 99% of dry air
and the remaining 1% consists of argon, carbon dioxide,
helium and other trace gases. Air, of course, also contains
water vapour and this may make up as much as 4% of
the total air volume. Clean air doesn't contain harmful
levels of chemicals or harmful chemicals which adversely
affect living things. Some gases which are normal
components of clean air - for example, carbon dioxide become dangerous when their concentrations become
much higher than normal.
1. Clean air and plants.
Lichens living on tree
trunks are very sensitive
to air pollution. They
can only survive in clean
air so are a good
measure of how polluted
the air is. Source:
www.freefoto.com
Air pollution has both natural and human sources.
2. Natural air pollution.
Smoke from volcano
Sakura-jima, Japan.
Source: UND - University of
North Dakota, photo: Mike
Lyvers
Natural air pollution comes from volcanoes, natural
forest fires, soil, plants, seawater, wetlands and
even outer space. Inputs of gases and particles from
these sources into the air has always happened and the
atmosphere adjusts to this new material with minimal
complications.
Human, or anthropogenic, air pollution comes from the many
different human activities which occur during our daily lives.
Sources include industry, vehicles, agriculture, power
generation (coal, oil or gas power stations), mining and waste
dumps. It is difficult for the atmosphere to cope with
these these extra pollutants leading to high
concentrations locally and regionally.
3. Anthropogenic
air pollution.
Smoke from a
factory chimney.
Source:
www.freefoto.com
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Air pollution can be divided into two basic types. Gases
come mainly from the burning of fossil fuels. Gaseous
pollutants which affect the atmosphere globally include
carbon dioxide (CO2), methane (CH4) and nitrous oxide
(N2O). These are all greenhouse gases and
are responsible for global warming.
4. Urban traffic.
Traffic delivers lots of
global and regional air
pollution
Source:
www.freefoto.com
Although present throughout much of the atmosphere,
gaseous pollutants including nitrogen oxides (NOx), sulfur
dioxide (SO2), carbon monoxide (CO) and a wide range of
organic compounds are found only in signficant
concentrations close to their origin so these are
important on a local and regional scale. All these
compounds are released during fossil fuel burning
although many volatile organic compounds (VOC's) also
have significant natural sources from plants.
Both the greenhouse gases and regionally important
gases are examples of primary pollutants. These
species are emitted directly into the air from sources
at the Earth’s surface.
The regional gases can also react chemically in the atmosphere to form other
compounds which are known as secondary pollutants. One of the main
results of secondary pollution is photochemical smog. Smog is the main
pollutant problem in most of the big cities of the world. Its main component is
ozone (O3) which, at high concentrations, can cause breathing problems and
burning eyes. While O3 is beneficial in the stratosphere because it absorbs
harmful ultraviolet radiation from the Sun, it is a health hazard in the lower
atmosphere. Use the link at the bottom of the page to find out more
about ozone smog.
The second type of pollutant is particulate
matter, which consists of a wide range of
liquid and solid particles known scientifically
as aerosols. The smallest of these particles
are hazardous to human health. As with
the gases, particles can be directly emitted
into the air or can form from gases. In
winter in many cities and towns,
particularly in poor countries, people burn
wood to keep warm. The particles
from wood-burning can cause a brown haze
over the region and larger particles may
interfere with plant growth because they
deposit on the leaves. See the link at the
bottom of the page to find out more
about aerosols and their origin.
5. Forest fires. Forests fires emit lots of
gases and particulate matter into the
atmosphere. Source: NASA - National
Aeronautics and Space Administration
Two hundred years ago, air pollutants were mainly from natural sources. The
rapid development of industry after 1850 created many new anthropogenic
pollution sources, which were initially associated with the production of energy
from coal and oil burning.
Air pollution is a major environmental issue in many parts of the world. Unless
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we control and manage air pollution carefully, air pollution problems will
become a lot worse.
The figure below summarises the criteria we use to classify air pollution. The
Colours in the text correspond to the colours used in the figure.
6. Air pollution classification. The colours in the figure correspond to the colours in the text where the
criteria are explained. Authors: Anita Bokwa, Michael Seesing, Pawel Jezioro.
Natural air pollution can be divided into:
- inorganic pollution, e.g. dust and gases from volcanic eruptions, salt
particles brought by the wind from the sea, dust delivered into the air
during dust storms, gases originating from lighting during thunderstorms and
dust coming to the atmosphere from space.
- organic pollution, includes smoke and dust from vegetation fires, pollen and
fungi from plants, live organisms including bacteria and volatile substances
emitted by trees and flowers.
Anthropogenic air pollution can be also divided into two groups according to
the character of emission:
- controlled emission which takes place according to well established rules,
under the supervision of trained staff.
- accidental emission which occurs, for example, during industrial accidents
and oil spills.
So we can define air pollution in two ways:
- primary pollution - harmful substances which are emitted directly into the
atmosphere.
- secondary pollution - substances which become harmful once in the air or
harmful substances which form as a result of chemical reactions in the
atmosphere.
7. Fire-places are probably one of the
first anthropogenic indoor sources of
air pollution. Source:
www.freefoto.com
The air pollution types mentioned so far are
also known as outdoor air pollution.
Indoor air pollution is also a very important
problem. The air within homes and other
buildings can sometimes be more polluted
than the outdoor air even in the largest and
most industrialised cities. Sources of indoor air
pollutants such as carbon monoxide
(CO) include poorly maintained fires, stoves
and heaters. This is a serious problem
particularly in poor countries where standards
of living are low.
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Other sources of indoor air
pollution include tobacco
products, products for household
cleaning and maintenance,
personal care, or hobbies.
Inadequate ventilation, high
temperatures and high humidity
allow the pollutants to
accumulate. Many people living
in the cities spend approximately
90% of their time indoors. So for
many people, exposure to indoor
air pollutants poses a greater risk
to their health than do outdoor air
pollutants.
8. Indoor pollution. Smoking a cigarette, pipe, or cigar
delivers a complex mixture of over 4,000 compounds,
more than 40 of which are known to cause cancer in
humans or animals and many of which are strong
irritants. Source: US Environmental Protection
Agency; photo: www.freefoto.com
Part 2: Causes
Causes of anthropogenic air pollution
Most of the air pollution which comes from human activity enters the
atmosphere from industry, vehicles and the combustion of fossil fuels in
power plants. In developed countries vehicles are the main source of
air pollutants in the cities.
Sources of anthropogenic air pollution
Combustion of fossil fuels during power production, in heating systems and in
vehicle engines is the main source of anthropogenic air pollution. Other sources
include industry and agriculture.
At the beginning of human
civilisation the only source of
anthropogenic air pollution
was smoke from fire-places. As
the population grew, air pollution
problems also increased. By
1273, King Edward the First of
England had banned the use of
coal in London as it caused
enormous air pollution problems.
1. Fire-places were one of the first anthropogenic
sources of air pollution. Source: www.freefoto.com
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In the 20th Century, industrial
development led to high
numbers of factories in
urban areas. This was
accompanied by a significant
increase in the urban population
and, as a result, the number of
buildings and cars grew. High
density housing and narrow roads
made vehicle traffic a particularly
important source of pollutants.
This is still a huge problem and in
cities of the developed
world, vehicles are now the most
important source of air pollution.
2. Intensively urbanised area. High concentrations of
residential buildings, service industries and factories in
urban and industrialised areas are one of the reasons
for air pollution. Source: www.freefoto.com
Emission and deposition
3. Emission and deposition (denoted imission on the
figure). Source: Bundesamt für Umwelt, Wald und
Landschaft 1996
Air pollutants are emitted from
urban areas and also from rural
locations. The harmful gases and
aerosols are transported by the
wind great distances away from
their initial source before they are
deposited back to the ground. So
when we measure the
concentration of a pollutant to
determine the air quality, we
must remember that the pollutant
may have come from some
distance away and doesn't
necessarily have a local source.
Units
While emission and deposition values are
usually given in large amounts (e.g. tonnes
per year), atmospheric concentrations are
generally expressed in much smaller units
(e.g. in fractions of grams or moles of a
substance per cubic metre of air). When we
look at atmospheric concentrations we can
either talk about average concentrations for
the whole Earth (in case of carbon dioxide
CO2), or for a given place and time (e.g.
sulphur dioxide SO2 levels in London, in
December 1952). Concentrations of gases are
often given as a mixing ratio, this is the
fraction of the compound as a proportion of all
the air molecules present. It is usually
expressed in ppm (parts per million) or ppb
(parts per billion). You can find out
more about the mixing ratio in the Higher
atmosphere topic.
4. Changes in global content (mixing
ratio) of carbon dioxide (CO2, in
ppm) and methane (CH4, in ppb) in the
atmosphere. Author: Anita Bokwa.
Source of data: World Resources
Institute (http://earthtrends.wri.org).
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Anthropogenic emissions
As we saw in the section "What is air pollution?", some emissions have a global
impact on climate while others have only a local effect. Areas with high levels
of anthropogenic air pollution include Eastern USA and Canada, Europe and
South and South East Asia. Emissions of sulphur dioxide (SO2) and nitrogen
oxides (NOx) from these areas contribute to acid rain and this effect is
discussed later in this topic. Large quantities of carbon dioxide (CO2) and
Volatile Organic Compounds (VOC's) are also emitted into the air. Some of the
VOC's (e.g. methane CH4 and the chlorofluorocarbons) can act as greenhouse
gases and we look at these in more detail in the section looking at the impact of
industry on air pollution.
The table below and the charts in figure 5 show air pollutant emissions in
selected countries. The emissions vary greatly and we look at the reasons for
these differences below using CO2 as an example.
Country
SOx
NOx
CO2
Dust
Great Britain
2 028
2 060
539 344
213
Hungary
657
197
58 498
136
Germany
1 468
1 803
834 379
316
France
989
1 691
344 666
211
Poland
2 368
1 154
348 260
1 282
South Korea
1 500
1 258
424 119
423
Japan
903
1 409
1 164 518
-
USA
18 481
21 394
5 444 794
3 393
Australia
1 842
2 166
316 704
38
Yearly emissions of sulphur dioxide, nitrogen oxides, carbon dioxide and dust
for selected countries (in thousands of tonnes per year).
5. a) Emissions of air pollutants in 1997.
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5. b) Emissions of CO2 in 1997
5. c) Emissions USA air pollutants in
1997.
5. Air pollution emissions in chosen countries. Please click icon to see enlarged chart! (15-30 K).
Authors: Anita Bokwa, Pawel Jezioro.
Source of data: Carbon Dioxide Information Analysis Center, United Nations Framework Convention
on Climate Change http://webdab.emep.int
Example:
Emissions which have global impact: Carbon dioxide (CO2)
Emissions of CO2 have a global impact on our climate. Let's see who emits the
largest amounts of CO2 in the world. According to the Energy Information
Administration, the global emission of CO2 in 2001 amounted to 6567.82 million
tonnes of carbon equivalent units.
What are carbon and carbon dioxide equivalent units?
Carbon equivalent units are defined as the carbon dioxide equivalent multiplied by the carbon
content of carbon dioxide (i.e., 12/44). The carbon dioxide equivalent is used to compare
greenhouse gases and is derived by multiplying the mass of the gas by its global warming
potential. The global warming potential measures how strong a greenhouse gas is. For example,
methane has a global warming potential of 21, so its 21 times more powerful a greenhouse gas than
CO2.
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Emissions by continents
About a third of the world's CO2 emissions
come from Asia, Australia and Oceania and
28% comes from North America. So almost
60% of the global CO2 emissions come from
these two regions. However, even though
both regions emit almost the same amount of
CO2 per year, the causes are quite different.
About 3.9 billion people live in Asia, Australia
and Oceania, that's 61% of the world
population, whereas only about 323 million
people live in North America (U.S.A. and
Canada).
High CO2 emissions in Asia, Australia and
Oceania are simply the result of the huge
number of people living in the region, in North
America it is the very high consumption of
energy which is the cause.
6. Emissions of CO2 in 2001 by
continents. Authors: Anita Bokwa,
Pawel Jezioro. Source of data:
www.eia.doe.gov/emeu/iea/
Emission by countries
7. Countries which had the largest share (in %) of the world total emission of CO2 in 1999.
Author: Elmar Uherek. Source of data: UN Human Development Report 2003
http://hdr.undp.org/reports/global/2003/pdf/hdr03_HDI.pdf
Figure 7 shows the countries which emit the largest amounts of CO2 in the world.
For example, 23.2% of global CO2 emissions come from the USA. USA, China
and Russia together make up over 42% of the global CO2 emissions although only
27% of the world's population lives in these countries. Among the seven largest
emitters, one is in North America, three are in Europe and three are in Asia (note
that although Russia is in both Europe and Asia, it is usually included with the
European countries). There are no large CO2 emitters in the Southern
Hemisphere.
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Emission per capita
Figure 8 shows how
much CO2 is
emitted per person in
certain countries. For
example, 19.7
tonnes of CO2 are
emitted per citizen
in the USA, while in
India it is only 1.1
tonnes. Such huge
differences result from
the different degree of
economic
development. The
higher the standard of
living in a country, the
higher the energy
consumption (through
the use of cars, air
conditioning and
electrical appliances)
and therefore the
greater the CO2
emissions.
8. Emissions of CO2 per capita in chosen countries.
Author: Elmar Uherek. Source of data: UN Human Development
Report 2003
http://hdr.undp.org/reports/global/2003/pdf/hdr03_HDI.pdf
Anthropogenic emissions by sectors
Anthropogenic air pollution comes from many sources. One source can often
emit many different pollutants but some human activities, for example
transport, produce very characteristic chemical species. The data from
UNECE/EMEP (United Nations Economic Commission for Europe/Co-operative
programme for monitoring and evaluation of long range transmission of air
pollutants in Europe) shows which sectors of the economy (what kind of
human activity) were mainly responsible for emissions of carbon monoxide
(CO), nitrogen oxides (NOx) and sulphur oxides (SO2) in Europe in 2001. The
emissions are given in gigagrams (Gg) where 1 Gg = 1000 tonnes.
Carbon monoxide (CO)
30,679 Gg of CO were emitted in
Europe in 2001. The main source
of this anthropogenic CO was
transport (60%) with industry
contributing 36%. Waste
management and agriculture
were of marginal importance. You
can find out more about CO
emissions in the topic on the
Lower Atmosphere.
9. Emission of CO in Europe in 2001 by sectors.
Authors: Anita Bokwa, Pawel Jezioro
Source of data: http://webdab.emep.int
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Nitrogen oxides (NOx)
10,056 Gg of NOx were emitted
into the atmosphere in 2001.
Transport was the biggest source,
making up 63% of the
emissions. Industry contributed
35% and emissions from waste
management and agriculture were,
again, of marginal importance.
10. Emission of NOx in Europe in 2001 by sectors.
Authors: Anita Bokwa, Pawel Jezioro
Source of data: http://webdab.emep.int
Oxidised sulphur compounds
(SOx)
The main component of the
oxidised sulphur compounds is
sulphur dioxide (SO2) and,
unlike CO and NOx, their main
source is industry. Total emissions
of oxidised sulphur were 5,949 Gg
in 2001 and 93% of these came
from industry. Find out more
about the impacts of SO2 and
NOx in the section on acid rain.
11. Emission of SOx in Europe in 2001 by sectors.
Authors: Anita Bokwa, Pawel Jezioro
Source of data: http://webdab.emep.int
Emissions in cities
12. Urban traffic
Urban traffic is the main source of air
pollution in many cities.
Source: www.freefoto.com
The main emission sources and the main air
pollutants vary between cities as they depend
on the poulation size, the types of industry
located there, how much traffic there is and
what kinds of heating systems are
used. Pollutants are emitted into the city
air from low emission sources (e.g. individual
heating systems in houses), high emission
sources (e.g. tall factory chimneys) and from
mobile sources (e.g. cars and buses). For
example, Cracow is a medium-sized city in
southern Poland with 800,000 inhabitants. It
has heavy industry (a steel works and a huge
power plant) and large amounts of traffic.
Industry emits almost all of the SO2 into the air,
most of the NOx and dust and as much CO as
transport. Other sources of air pollution are of
marginal importance. However, in
many Western European cities, transport is the
main source of CO and NOx, because heavy
industry has declined and ben replaced with
clean new technologies.
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sector/pollutant
CO
NOx
dust
transportation
48%
15%
2%
industry
44%
83%
88%
8%
2%
10%
100%
100%
100%
municipal economy
sum
Emission of carbon monoxide (CO), nitrogen oxides (NOx) and dust by sectors
in Cracow, Poland, in 2001. Source: Inspectorate of Environmental Protection
in Cracow.
Part 3: Negative effects
Negative effects of air pollution
Air pollution has an impact on both local and global scales. Harmful
substances which are emitted into the atmosphere in one country, are
transported by the wind and cross over national borders. International
co-operation is, therefore, necessary to improve overall air quality.
Global negative effects of air pollution include the enhanced greenhouse effect
and the ozone hole. Smog and acid rain are the best known local effects and
smog, in particular, affects people living in urban areas. Air pollution is a threat
to our health and can also cause economic losses.
Let's concentrate on air pollution in cities.
Sulphur and nitrogen oxides, hydrocarbons
(mainly from refineries and traffic), carbon
monoxide, heavy metals (from traffic and
industry), dust and soot are all found in urban
air. The proportions of these pollutants vary
depending on the location. For example, use
of low sulphur containing fuels has
dramatically decreased the atmospheric
concentrations of sulphur dioxide in developed
countries.
1. Urban air pollution. Individual
heating systems contribute to the urban
air pollution. Source:
www.freefoto.com
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Smog
In many cities, air pollution levels exceed the allowed concentrations and smog
alarms are published. The word "smog" is the combination of the words smoke
and fog, it was invented around 1911 by the physician Harold Des Voeux.
There are two kinds of smog:
- London-type smog.
Burning coal leads to
emissions of sulphur dioxide
and dust. When these
pollutants mix with fog,
droplets of highly corrosive
sulphuric acid (H2SO4) are
produced in the air. In
London in 1952,
concentrations of SO2 during
a smog event exceeded 3.5
mg m-3 (3500 µg m-3) and
many people died. London
type smogs were first
recorded in the 1850's and
are rather rare today due to
better controls on air
pollution. For example, in
2001, mean annual
concentrations of SO2
reached 3 µg m-3 in
Barcelona (Spain), 4 µg m-3
in Munich (Germany), 7 µg
m-3 in London (Great Britain
- data for 1999) and 13 µg
m-3 in Warsaw (Poland). On
some days,
however, concentrations of 2. Number of deaths in London in December 1952 due to high
of sulphur dioxide. Source: Manchester
SO2 can be much higher. The concentrations
Metropolitan University
highest hourly values for
SO2 in 2001 were 211 µg m3
in Warsaw, 106 µg m-3 in
London (1999), 70 µg m-3 in
Barcelona and 17 µg m-3 in
Munich.
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- Los Angeles-type or
photochemical smog. This
type of smog forms on sunny
days and is the result
of emissions from traffic.
Nitrogen oxides from
car exhausts and
hydrocarbons from various
anthropogenic and biogenic
sources react in the presence
of sunlight to produce a
noxious mixture of aerosols
and gases. Photochemical
smog contains tropospheric
ozone, formaldehyde,
ketones and PAN
(peroxyacetyl nitrates).
Normal tropospheric ozone
levels are less than 0.04 ppm
but ozone levels can be as
high as 12 ppm in these
smogs. The substances in
these smogs are irritating
to our eyes and can damage
our respiratory system. They
also affect vegetation. This
type of smog is rather
common now in large cities in
the summer and
has generally replaced the
London-type smog.
3. What is smog and when is it formed?. Authors: Anita
Bokwa, Michael Seesing.
For more information on
concentrations and mixing
ratios see the topic on the
Higher atmosphere.
Dust and soot
Another problem in cities is dust and soot. In 1999, for example, the mean
annual concentration of particulate matter less than 10 micrometers in diameter
(PM10) was 21.8 µg m-3 in London, 29.5 in Budapest, 43.3 in Rome, 44.4 in
Sevilla and 45.4 in Cracow. These values have decreased with time due to better
pollution control measures. For example, annual mean particulate concentrations
in Cracow in the 1970's and 1980's exceeded 100 µg m-3 due to emissions from
the steel factory and the power plant and reached levels of 200 µg m-3 in the
winter. These factories have since been modernised and production has
decreased leading to significant improvements in air quality.
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4. Mean annual concentration of particulate matter less than 10 µm in diameter in 1999. Source:
APHEIS - Monitoring the Effects of Air Pollution on Health in Europe.
Limit values
For every pollutant there are established limit
values of concentration which should not be
exceeded. These limits are designed to prevent
damage to human health and to the
environment. For the European Union
countries, the limit values and alert thresholds
for ambient air were established with the
Council Directive 96/62/EC, 27 September,
1996. Detailed regulations were included in
three Council Directives: 1. 1999/30/EC, 22
April, 1999; 2. 2000/69/EC, 16 November,
2000, and 3. 2002/3/EC, 12 February, 2002.
6. Limit values for NO2, SO2, Pb and PM10
(mean annual concentrations) in the countries
of the European Union. Author: Pawel
Jezioro.
5. European flag, a symbol of united
Europe.
As air pollution is an international
problem, the legal regulations about
emissions are established by
the Council of the European Union for
all the member countries. Source:
www.freefoto.com.
For nitrogen dioxide (NO2), sulphur
dioxide (SO2), lead (Pb) and
particulate matter up to 10 µm in
diameter (PM10), the limit values are
given as mean annual concentrations.
This means that on any particular day,
the concentrations may be higher than
the limit value, while on other days it
may be much lower, but on average over
the whole year, the limit value should not
be exceeded. The limit values for SO2
and Pb are much lower than those for
NO2 and PM10, as these substances are
more harmful to human health.
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For ozone (O3) and carbon monoxide (CO),
the limit values are given as 8-hour mean
concentrations. These gases are very toxic
to people even in very small amounts and
over short exposure periods. As you can
see, allowed amounts of ozone in the air are
much lower than for CO. Low level ozone is
formed during photochemical smog episodes
and is harmful to us, whereas ozone in the
stratosphere protects life on Earth.
7. Limit values for O3 and CO (8-hour
mean concentrations) in the
countries of the European Union.
Author: Pawel Jezioro.
Alarm values
For NO2, SO2 and O3, as well as the limit
values, alarm values have also been
established. These are 1-hour
mean concentrations. If these values are
exceeded, the local authorities should first
inform the public and then undertake actions
that decrease the pollutants' concentration in
the air. For example, they may have to limit the
traffic in a city or decrease industrial production
until levels of the pollutant have declined
sufficiently.
8. Alarm values for NO2, SO2 and O3
(mean 1-hour concentrations) in the
countries of the European Union.
Author: Pawel Jezioro.
Part 4: Areas in danger
Areas endangered by air pollution
The air above densely populated urbanised areas always contains many
unwanted substances. Industrial accidents may spread air pollution to
previously clean areas.
We have already looked at air pollutants which have either global or local
influence. The local effects of air pollution include reductions in the quality of
the soil, water and vegetation.
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Air pollution: an international problem
1.
Map of Black Triangle area. Source: Inspectorate of Environmental Protection in Wroclaw.
Branch Jelenia Gora.
Winds transport air pollutants from one place to another, even from one country
to another. As a result, the impact of a particular pollutant may be felt far away
from the emission source. A good example is the so-called "Black Triangle", an
area located at the junction of the Polish, German and Czech borders. In this
region there are three big lignite fields where brown coal is mined: Turoszow
field, Lusatian field and North-Czech field, together with seven power plants
producing 16,000 MWatts of energy. In 1989 this region, covering just 32,400
km2, was responsible for 30% of the total European emissions of SO2. These SO2
emissions contribute significantly to the acid rain problem (see the section on
Areas endangered by acid rain).
Acid rain falling in this region caused the largest European event of mountain
forest decay seen so far. Between 1981 and 1987, 11,000 hectares of spruce
forest in the Sudety Mountains were damaged, of which 10,000 hectares were in
the Western Sudety area. At the same time, 15,000 hectares of forest were
destroyed in the North West Czech Republic and Saxony.
At the beginning of the 1990's co-operation between the three countries lead to
action being taken to improve the natural environment. In 1992, an integrated
network of 43 automatic monitoring stations was established in Poland, The
Czech Republic and Germany and SO2 sources were reduced
by modernising power plants and heating systems. Another factor
which contributed to the improvement of air quality was the economic crisis and
decrease in industrial production in Central European countries. As a result of all
these factors, emissions of harmful substances decrease every year.
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2. Dust, SO2 and NOx emissions in the Black Triangle Area.Source: Inspectorate of Environmental
Protection in Wroclaw. Branch Jelenia Gora.
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Industrial catastrophes
Technological risk is an element
which has accompanied industrial
development right from its
beginning. Every installation
may malfunction at some point
during its operation and people
working with the machines and
systems can always
make mistakes. When an
industrial catastrophe takes place,
the atmosphere usually gets
3. Chemical complex
polluted with very toxic chemicals
Source: www.freefoto.com
or radioactive substances, for
example in the case of nuclear
power plant disaster.
Here are a few examples of such events and their effects:
- 1930 - smog in the Mosa valley (Belgium), sulphur dioxide air pollution caused
the death of a few hundred people.
- 1948 - Donora (USA), smog killed 20 people.
- 1950 - Pozza Rica (Mexico), uncontrolled emissions of hydrogen sulfide (H2S)
during a plant malfunction caused respiratory problems in over 300 persons
and 22 people died.
- 1952 - smog in London, four thousand people died.
- 1984 - chemical catastrophe in Bhopal (India), 3400 people died, 600
thousand suffered from respiratory problems.
- 1986 - accident at the nuclear power plant in Chernobyl (former USSR,
present Ukraine), 31 people died in the first week after the explosion, the exact
total number victims are not still not known today; it is estimated that a few
million people still suffer from diseases caused by the radiation: cancer (an
increase in thyroid cancer has been observed in the surrounding area),
immunological dysfunction etc.; large areas were polluted for many years.
- 1991-92 - oil fires during the war in Kuwait and Iraq.
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