• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Photochemical smog is the most widely known and perhaps most serious air pollutant. It is formed in the atmosphere by the reaction between gaseous pollutants, nitrogen oxides and hydrocarbons

Extracts from this document...


Photochemical Smog Photochemical smog is the most widely known and perhaps most serious air pollutant. It is formed in the atmosphere by the reaction between gaseous pollutants, nitrogen oxides and hydrocarbons in the presence of strong sunlight. These gases are from motor vehicle exhaust and commercial/industrial processes. The two types of pollutants that produce photochemical smog are primary pollutants and secondary pollutants. Primary pollutants are harmful substances put directly into the air by human activity. The main types of primary pollutants responsible for photochemical smog are: * NOx (Oxides of nitrogen) * Volatile organic compounds(VOC) * CO( Carbon monoxide) The secondary pollutants are: * Ozone(O3) * Nitrogen dioxide(NO2) * Hydrogen peroxide(H2O2) * Peroxyacetyl nitrate(PAN) These are the equations in the formation of photochemical smog:[2] NO2 (in presence if sunlight) ? NO + O. O + O2 ? O3 O3 + hydrocarbons ? aldehydes Hydrocarbons + O2 + NO2 ? lachrymatory substances (like PAN) Pollution form a coal power station Coal-fired power stations are major sources of pollution. The extensive use of coal is because there is a lot of it around. ...read more.


Topography is another important factor influencing how severe a smog event can become. [1] Formation of OZONE Ozone is present in the air that surrounds us. It is formed when hydrocarbons and nitrogen oxides (NOx) from forests, industries, and automobile exhaust react with heat and sunlight. This tropospheric ozone is often called "bad" ozone because it damages living tissue. Some tropospheric ozone is natural. Lightning and static discharges are one natural source of tropospheric ozone. Some ozone is also produced when natural hydrocarbons formed by trees and other vegetation react with nitrogen oxides in the atmosphere and sunlight. O2+O ? O3 Ozone reacts with NO to form NO2 O3+NO ? O2+ NO2 Processes to control SO2 and NOx A power station manager should make some important decisions which are concerned with minimising the effects of the waste, from the power station, on the environment. This is known as Best Practical Environmental Option(BPEO). The BPEO may vary in different power stations. The sulphur dioxide emissions from the power station can be removed by reacting it in the power stations flue gas with limestone, eventually forming calcium sulphate (CaSO4). ...read more.


This method is adapted mostly because it delivers low cost power and causes minimum spoiling of the environment. Research on photochemical smog formation Research work is taking place on several fronts to discover the chemistry of the formation of photochemical smog 1. Monitoring of tropospheric pollutants An important step is to know which pollutants are present in the atmosphere. Several monitoring stations which record pollutant concentrations are now plenty in the country. 2. Studying individual reactions in the laboratory To make predictions about pollutions, chemists need to know what reactions can take place and how quickly they occur. They have to measure the rate at which each reaction takes place under a variety of conditions from which they can predict how the rate of a reaction will proceed for different conditions 3. Modelling studies The information on rate of reactions is used in computer simulation to reproduce and predict the behaviour of pollutants in a photochemical episode. Accurate information is required for close simulation if the observed behaviour. 4. Smog chamber simulations These are laboratory experiments in which primary pollutants are mixed in a huge plastic smog chamber and exposed to sunlight under carefully controlled conditions. The concentration of various species is monitored as the photochemical smog builds up. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Atmosphere & Weathering section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Atmosphere & Weathering essays

  1. Outline the challenges and opportunities for human activity in present peri-glacial environments

    Employment generated by the tourist industry has meant that jobs are available locally where unemployment was before a big problem. Economic profit made can also be used to improve the area as it becomes more developed, better communications and infrastructure is needed that can benefit tourists and locals alike.

  2. The aim of this project was to investigate what differences exist in temperatures in ...

    For the duration of winter, the seas retain some of their heat, and so the coastal regions of the south - west are the warmest. As the temperatures warm up, the sea takes longer to warm up, and so the coastal regions close to the prevailing winds remain cooler, and

  1. Outline the main causes of air movement. Discuss the application and limitations of the ...

    The rising air cools to the surrounding environmental temperature so uplift ceases and moves away from the equator. As the air continues to cool the density increases causing it to subside at the subtropical high pressure belt leaving clear skies and dry stable conditions creating desert climates.

  2. Free essay

    Conserving or Removing Mangroves

    previously acted as buffer zones are cleared, leaving the coast open to direct erosion by waves and these other natural processes. The life and property of locals is at stake as the sea slowly swallows the coast. Some ponds have been abandoned due to the erosion, acid sulphate soil conditions and occasional mass mortality of prawns due to disease outbreaks.

  1. Energy tranfers within the atmosphere

    The albedo effect occurs in various ways hence why there is diversity in the percentage of reflected and absorbed heat and light in the constituents of the earth's surface. The term albedo is derived from the Latin name for white, hence its relevance for this process.

  2. Climate in different cities around the world

    in July. Ski resorts open in late November and remain so until the snow begins to melt in April. Switzerland is ideal for skiing in the right season and the majority of tourists that visit Switzerland go for the winter sports.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work