Overview of Air Pollution, The Chemistry Behind Pollution - page 3
Keywords: Environmental Studies
By Vickiduduu on 10/11/2007
Level: Foundation Degree
Page Number: 3 of 5 pages: 1 2 3 4 5
the ability to remove O3 by forming NO2 and O2. So, when the concentration of NO2 is below a certain level then the Nitric Oxide reaction will dominate therefore removing the excess O3.
Another primary pollutant released when fossil fuels are burned is Hydrocarbons, often referred to as VOC’s. Hydrocarbons have many other major sources. Methane, a type of Hydrocarbon, is present in the atmosphere from natural sources at very high concentrations. Hydrocarbons are emitted by vegetation and vehicle emissions along with use of solvents in industry are large contributors to the hydrocarbon pollution levels.
Hydrocarbons are naturally removed from the troposphere by an oxidation reaction occurring between the hydrocarbons and a hydroxyl radial produced by UV light interacting with Ozone. This reaction eventually produces less complex, more stable molecules which are oxidised producing carbon dioxide and water.
If combustion processes are carried out with a limited supply of Oxygen then Carbon monoxide (CO) is produced and released into the atmosphere. A typical example of this is the incomplete combustion of exhaust gases. Most Carbon Monoxide once released into the troposphere readily reacts with oxygen to form carbon dioxide. Increased Carbon dioxide levels mean an increase in greenhouse gases and global warming.
The last primary pollution category is particulate matter. Road transport accounts for around 25% of particulate matter, other major sources are industrial plants, power generation and residential combustion. As with other pollutants particulates are released naturally too, these sources include volcanoes and severe winds blowing up dust particles from ground level.
Particulates occur in the atmosphere as solid and liquid particles. They can be split in to two groups: fine particles, with a diameter of less than 2.5 µm, and coarse particles with a diameter greater than 2.5µm. Particulates can also be classified as primary or secondary. Fine particulates are often formed by other pollutants reacting once in the atmosphere, these are known as secondary particulates and contain aerosols and re-condensed organic vapours. Whereas coarse particulate matter usually contains sea salt particles, fertilizer dusts and products of combustion such as soot.
What does all this mean for us as humans? And how does it affect our planet? There are many different affects of all of these pollutants, most of which are irreversible. If we can learn how to care for the atmosphere we can maybe limit further damage to our environment and ourselves.
Particulates are responsible for many early deaths, as fine
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