Māris kļaviņŠ, azamat azizov, JĀnis zaļoksnis environment, pollution, development: the case of uzbekistan

Figure 5.1. 
Production 
amounts of hazardous 
chemicals in the 
European Union 
Member States. 
CMR – carcinogenic 
(causing cancer), 
mutagenic (causing 
mutation) and 
reprotoxic (toxic to 
reproduction). The 
influence of CMR 
substances can increase 
the risk of formation 
of malignant tumours 
and mutations as well 
as cause reproductive 
system problems, 
affecting the offspring

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5. GLOBAL ENVIRONMENTAL PROBLEMS
 77
 5.2. 
 Global environmental pollution problems
 5.2.1.  Earth’s ozone layer and the consequences of its 
depletion
Ozone (O
3
) is one of the oxygen molecule forms composed of 
three interconnected oxygen atoms. Ozone is a pale blue gas that 
has a higher density than air. Ozone is formed when energy – for 
example, electro magnetic radiation – splits the oxygen molecules. As 
a chemical substance, ozone is a powerful oxidant. The presence of 
ozone in the atmo sphere, its formation and disintegration reactions 
are vital for the absorption of the UV radiation from the Sun.
The ozone concentration near the Earth’s surface is ~0.001% by 
volume, whereas in the stratosphere its concentration may be even 
more than 100 times higher. Nonetheless, the ozone concentration 
in the stratosphere is relatively low because the air in this layer of 
the  atmo sphere  mostly  consists  of  nitrogen  (78%),  oxygen  (21%) 
and argon (~1%). The ozone layer (its thickness in the atmo sphere 
under  normal  conditions  is  approximately  2.5 mm  if  only  the 
dispersed ozone molecules were gathered together) protects the 
biosphere from the ultraviolet part of the solar radiation spectrum. 
The ozone concentration in the atmo sphere mostly depends on the 
latitude, season, solar activity and other factors. The ozone layer is 
thickest at the height of 25-30 kilometres in equatorial regions and 
15-20 kilometres around the Earth’s poles (Figure 5.3).
A
lti
tu
de
 (k
m)
0                      5                    10                    15                    20
0
35
30
25
20
15
10
5
40
29 July 1998
8 October 1997
3 October 1998
UV-C
UV-B
UV-A