HC belong to a larger group of chemicals known as volatile organic compounds VOC. HC are compounds of hydrogen and carbon only, while VOC may contain other elements. They are produced by incomplete combustion of hydrocarbon fuels, and also by their evaporation. Because there are many hundreds of different compounds, HC and VOC display a wide range of properties. Some, such as benzene, are carcinogenic; some are toxic and others harmless to health. Fossil fuels contain traces of sulphur compounds, and SO2 is produced when they are burnt.
The majority of the SO2 emitted to the air is from power generation, and the contribution from transport sources is small shipping being an exception. Exposure to SO2 can damage health by its action on the bronchial system.
Sulphuric acid generated from atmospheric reactions of SO2 is the main constituent of acid rain, and ammonium sulphate particles are the most abundant secondary particles found in air. CO is an odourless, tasteless and colourless gas produced by the incomplete burning of materials which contain carbon, including most transport fuels.
It is non-flammable and will not support combustion. You probably remember learning about the nitrogen cycle in school and how it is crucial to all life on earth. At normal pressure and temperature, molecules of oxygen bind to form dioxygen O 2 which is present in the atmosphere. Oxygen is the third most abundant element in the universe, and of course is crucial to our continued existence. Interesting fact: the most common auroral colour pale yellowish-green in the northern lights is produced by oxygen molecules located about 60 miles above the earth.
How cool is that! At room temperature, nitrogen is a very inactive gas — a couch potato, you might say.
But sparks can fly between these two. In the presence of lightning or a spark, nitrogen combines with oxygen to form several different oxides. Nitrogen monoxide or nitric oxide NO and nitrogen dioxide NO 2 are the most abundant. NO x molecules have nitrogen and oxygen atoms in them. Nitrogen oxides are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures.
At normal temperatures, oxygen and nitrogen gases do not react together. Nitrogen oxides are produced naturally from a lightning strike. A bolt of lightning can reach temperatures of roughly 30, kelvins 53, degrees Fahrenheit.
How many times does lighting strike the earth you might ask? In large cities, nitrogen oxides are produced from fuel combustion in mobile and stationary sources. The combustion of gasoline in automobiles emit nitrogen oxides into the atmosphere mobile source. Stationary emissions come from coal fired power plants, electric power plant boilers. Natural sources: Mainly thunderstorms due to the extreme heat of lightning.
Unlike emissions of sulphur dioxide, emissions of nitrogen oxides are only falling slowly in the UK, as emission control strategies for stationary and mobile sources are offset by increasing numbers of road vehicles.
Emissions from electricity generation - NOx emissions from electricity generation are fairly constant from onwards until During the early s the increased use of gas in electricity generation displaced coal and oil DECC, The cleaner fuel and more modern power stations led to a significant reduction in NOx emissions from the sector until From , the absolute level of gas used for electricity generation remained fairly constant, and increased demand was met by coal-fired power stations.
Since , coal use and the total amount of fuel used in electricity generation has substantially decreased DECC, NOx emissions from road transport - the road transport sector has provided a significant contribution to the downward trend in UK emissions.
The first petrol cars with three-way catalysts were introduced in , and this resulted in a significant reduction in NOx emissions. Email: technical. Email: sales. This site uses cookies in accordance with our Website Privacy Policy. By continuing to browse the site you are agreeing to our use of cookies. To browse without the use of cookies, you can opt-out as explained in our Website Privacy Policy or adjust your cookie settings for your browser.
Part of BMI Group. Skip to navigation. What is it? See our video on how the Noxite solution depollutes the built environment Nitrogen dioxide is an irritant gas, which at high concentrations causes inflammation of the airways. Sources of NOx Pollution NOx is produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures.
0コメント