Wednesday, February 24, 2010

AIR POLLUTION

Air pollution means the presence of one or more unwanted substances in air. Air pollutants have a negative impacts on humans, animals and plants, and on air quality.
What causes air pollution?
The main sources of air pollution are the industries, agriculture and traffic, as well as energy generation. During combustion processes and other production processes air pollutants are emitted. Some of these substances are not directly damaging to air quality, but will form harmful air pollutants by reactions with other substances that are present in air.Examples of large-scale air pollutants are VOC (Volatile Organic Compounds) and small dust particles. When large concentrations of these substances are emitted this negatively affects ecosystems, materials and public health.Traffic is held responsible for one-third of the greenhouse gas emissions. Emissions caused by traffic are mainly those of carbon dioxide, carbon monoxide, nitrogen oxides, VOC and small dust particles.Consumers are also partly responsible for air pollution. Firstly because the products they use have caused air pollution during their production and distribution and secondly because heating of houses and offices causes chemicals release into the air.
How does air pollution spread and how can we handle this?
The dispersion of air pollutants mainly depends on physical processes is air; those of wind and weather. How far air pollutants are transported mainly depends upon particle size of the compounds and at which height the pollution was emitted into the air. Fumes that are emitted into air through high smoke stags will mix with air so that local concentrations are not very high. However, wind will transport compounds and the pollution will become very disperse. Rain can remove pollutants from air. This causes precipitation and consequentially soil and water pollution.For environmental agencies it is very important to determine exactly how an air pollutant spreads. Air is not a very complex medium. This enables us to predict the dispersion of air pollutants with computer models. In a computer model dispersion is calculated by means of different parameters, such as wind speed, wind direction, temperature, air humidity and cloudiness. These predictions are of great significance when we are dealing with toxic clouds or radioactive radiation, because these are a danger to human health and because inhabitants of polluted areas need to be warned.


Häli Nelis, Epp Mänd, Krete Kiider; 12D

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