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UNIT 1: WHERE DO WE STAND? THE STATE OF THE GLOBAL ENVIRONMENT
027
1.7 Air Pollution
Deterioration in air quality is considered to have occurred when substances (gases
and particles) in the atmosphere exist at higher concentrations than the normal
background or ‘ambient’ levels and cause measurable effects on humans, plants,
animals and materials.
S
E
C
T
I
O
N
1
Global carbon dioxide emissions
1,000 million tonnes CO2/year
25
20
15
10
5
0
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995
Source: CDIAC 1999/Published in Global Environment Outlook 2000, UNEP
Carbon dioxide emissions per capita
tonnes/year
20
18
16
14
12
10
8
6
4
2
19.93
19.11
8.78
7.93
4.88
7.35
2.03
2.55
1.27
2.23
1975
1995
0.94
Global carbon
dioxide
emissions
continue to
mount. Average
annual increase
over the past
decade has been
1.3 per cent or
nearly 300
million tonnes a
year
Only in Europe
have per capita
emissions of
carbon dioxide
declined over the
past 20 years.
Emissions are
much higher in
North America
than in other
regions
0
North
America
Europe and
Central Asia
West Asia
Latin America
and the
Caribbean
Asia and
the Pacific
Africa
Source: compiled by UNEP GRID Geneva from CDIAC 1998 and WRI, UNEP, UNDP and WB 1998/
Published in Global Environment Outlook 2000, UNEP
Air pollutants can be classified as primary pollutants and secondary pollutants.
A primary pollutant is one emitted by an identifiable source. The most significant
primary pollutants today are:
• Carbon monoxide (CO);
• Nitrogen oxides;
• Sulphur dioxide;
• Sulphur oxide;