Photochemical Smog

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by TeamE14
Last updated 6 years ago


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Photochemical Smog

Photochemical Smog

Our Problem

Control Measures

Reducing Photochemical smog...




Why did it happen?


The Great Smog of 1952 2013 Southeast Asian haze

2013 Southeast Asian HazeThe haze was caused by the smoke emitted from fire burning in Riau province, Indonesia. Countries affected includes Brunei,Singapore,Thailand ,Malaysia and Indonesia.The PSI (Polluntant Standards Index) had reached a hazardous range of 401 in Singapore.

Photochemical smog is a type of air pollutant formed when nitrogen oxides (from lightning activity and internal combustion engine) and volatile organic compounds (such as methane from decayed plant and animal matter) reacts with sunlight to form harmful chemicals such as ozone(O3), aldehydes(an organic compound formed by oxidation of alcohol) and peroxyacetylnitrate(a thermally unstable substance that decomposes into peroxyethanoyl radicals and nitrogen dioxide gas). EffectsPhotochemical smog can cause health problems which include breathing difficulties, headaches,fatigue and respiratory problems. Irritation in eyes and lungs will be common as well. It also causes damage to lung tissue and weaken the lungs' ability to exchange gases.Premature death and birth defects are also some of the impacts from photochemical smog.Other than health Issues, photochemical smog also has great impacts on to the environment. Methane, a greenhouse gas, causes global warming by absorbing infrared radiation. Global warming would melt the ice caps in the North and South Pole, leading to an increase of the sea level, thus, causing low-lying area to be flooded. Ozone formed damages crop and affects the livelihood of farmers and the supply of crops. -

Catalytic converters in the car’s exhaust system- CO2 and H2O are products of reaction from the metal catalyst and CO and unburnt hydrocarbons. CO2 and H2O are less harmful.-Nitrogen oxides from exhaust gas are reduced into harmless substances O2 and N2.-Absence of nitrogen oxides and unburnt hydrocarbons while limiting exposure to sunlight -Volatile Organic Compounds is eliminated from the formation of ozone which reduces the formation of photochemical smog.Other Methods-Limit urban space by restricting future development and designating locations in and around existing urban areas-Use clean fuels. The products of combustion from the fuels are harmless. (E.g. Water)-Use electric cars to reduce exhaust gas emissions.-Carpool to reduce use of car.

Photochemical smog is...

The following substances are identified in photochemical smog:- Nitrogen Oxide (NO)NO2+Sunlight→NO+O- Nitrogen Dioxide (NO2)O3+NO→O2+NO2- Ozone (O3)O.+O2→O3 - Volatile organic compounds (RH)The process of formation of photochemical smog is explained in the video below:


Oxygen radical formed when oxygen atom overcomes intermolecular force in thesimple molecular structure of NO2.

The Great Smog of 1952The smog surrounding London from 5-9 December of 1952 led to poor visibility and 12,000 deaths. Operations was disrupted as transportation ceased and people remained at home due to fear of getting lost in the streets. Burning of low quality coals increases the emission ofsulphur dioxide and air pollutantsproduced from vehicle exhaust which led to the formation of photochemical smog.

*PSI is an air quality indicator which considers the concentration of sulphur dioxide, particulate matter (PM10),fine particulate matter (PM2.5), nitrogen dioxide,carbon monoxide and ozone in the air.

PSI reached 401 in Singapore on 21June 2013,12 noon.

Cause of Photochemical Smog


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