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

Figure 7.17. 
The internal 
combustion engine 
work cycle

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134 
ENVIRONMENT, POLLUTION, DEVELOPMENT:  THE CASE OF UZBEKISTAN
From the labour safety point of view a danger may be caused by 
increased discharge of nitrogen oxides during the electric welding 
processes,  especially  in  confined  spaces.  Nitrogen  oxides  are  also 
formed in the combustion of nitrogen organic compounds present 
in  the  fuel,  and  this  process  can  take  place  at  significantly  lower 
temperatures than NO
x 
thermal synthesis.
The resulting HNO
3
 mainly falls down by precipitation in 
the form of both acid and salts. Of nitrate salts, ammonium 
nitrate (NH
4
NO
3
) is mainly found in the atmo sphere. Since the 
photochemical transformations of nitric oxides and also their 
elimination from the atmo sphere take place rather quickly, the 
acidification of precipitation as a result of nitrogen presence has a 
significant impact on the regions near to the pollution sources.
Taking  into  account  the  significant  amounts  of  nitrogen  oxide 
produced (total global emissions of 86 million tons / per year), they 
can adversely affect the on-going processes in the environ ment, as 
well as human and animal health.
Overall, nitrogen oxide emissions in Europe are now among 
the most dangerous contemporary environ mental pollution factors. 
These issues are especially topical in the Baltic Sea region countries, 
where the nitrogen compound load determines many of the negative 
processes that take place in this region. Thus, a matter of actual 
nitrogen oxide emission control – the restraint – becomes urgent.
Traffic  of  motor  vehicles  is  considered  to  be  one  of  the  major 
sources of nitrogen oxides, which directly affects the air quality in 
cities (Figure 7.18) and the growing number of cars in the streets is 
increasing the nitrogen oxide concentration.
0
20
40
60
80
100
120
0
1000
2000
3000
4000
5000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Concentration, µg/m
3
Number 
of cars
Hour
Number of cars
Concentration of nitrogen oxides
In 2005, the transport in Latvia created already as much as 
52% of the total NO
x
 emissions. The relative impact of transport on 
Once in the atmosphere, 
nitrogen oxides become 
involved in various che‑
mical reactions. Nitrogen 
oxides, which have en‑
tered stratosphere, may