Photochemical Smog :: essays research papers fc

Photochemical SmogHistorically, the term smogginess referred to a mixture of smoke and fog, hence thename smog. The industrial revolution has been the central energise for the increasein pollutants in the atmosphere over the last three centuries. Before 1950, themajority of this contaminant was created from the burning of coal for energygeneration, space heating, cooking, and transportation. below the rightconditions, the smoke and sulfur dioxide produced from the burning of coal rottercombine with fog to create industrial smog. In high concentrations, industrialsmog can be passing toxic to humans and other living organisms. London isworld famous for its episodes of industrial smog. The most famous London smog item occurred in December, 1952 when five days of calm foggy weather created atoxic atmosphere that claimed about 4000 human lives. Today, the use of otherfossil fuels, thermonuclear power, and hydroelectricity instead of coal has greatly keep downd the occurrence of ind ustrial smog. However, the burning of fossil fuelslike gasoline can create another atmospheric pollution problem known asphotochemical smog. Photochemical smog is a condition that develops when primarypollutants (oxides of nitrogen and volatile organic compounds created fromfossil fuel combustion) move under the influence of sunlight to produce amixture of hundreds of different and hazardous chemicals known as secondarypollutants. Development of photochemical smog is typically associated withspecific climatic conditions and centers of high population density. Citieslike Los Angeles, New York, Sydney, and Vancouver frequently suffer episodes ofphotochemical smog.One way in which the production of photochemical smog is initiated is throughthe photochemical reaction of nitrogen dioxide (NO2) to form ozone. There aremany sources of photochemical smog, including vehicle engines (the number onecause of photochemical smog), industrial emissions, and area sources (the lossof vapors from sm all areas such as a local service station, surface coatings andthinners, and natural gas leakage).Vehicle engines, which are extremely numerous in all parts of the world, do notcompletely burn the petroleum they use as fuel. This produces nitrogen dioxidewhich is released through the vehicle squirt along with a high concentration ofhydrocarbons. The absorption of solar radiation by the nitrogen dioxide resultsin the formation of ozone (O3). Ozone reacts with many different hydrocarbons toproduce a brownish-yellow gaseous cloud which may contain numerous chemicalcompounds, the combination of which, we call photochemical smog.Both types of smog can greatly reduce visibility. Even more importantly, theypose a serious threat to our health. They form as a result of extremely highconcentrations of pollutants that are trapped neighboring the surface by a temperature