Atmospheric pollution


atmospheric pollution 

problem: 1 billion people exposed to outdoor air pollution, 90% of air pollution in LEDCs comes from oil motor vehicles which are poorly maintained 

primary pollutants: emitted direclty from polluting prcocesses, source be natural/anthroprogenic. greatest emitter fossil fuel combustion creates primary polllutants:  carbon monoxide, carbon dioxide, unburned hydrocarbons, nitrogen oxides, sulphur oxides, particulate matter 

secondary pollutants: formed when primary pollutants undergo reactiosn with other chemicals present in the atmosphere, sometimes this is a photochemica reaction in the presence of sungligh e.g. tropospheric ozone, particles produced from gaseous primary pollutants, peroxyacetyl nitrate 

atmospheric pollution behvaiour: 

  • behave differently compared to on ground/in water 
  • transboundry, large areas of dispersal 
  • interact easily with electromagnetic radiations e.g, UV from the suns visible light = photochemical reactions = secondary pollutans 
  • interact with infra read energy radiated from earth 


sources: inomplete combustion of carbon based materials produce smoke, combustion of wood fuel = small suspended solid particles in the atmosphere = measured by size range of particles

particle size important: smaller particles remain in atmosphere for longer likely be inhaled 

PM10: <10 microns in diameter 

PM5: <5 microns in diameter 

PM1: <1 micron in diameter 

smoke is made of particles of varying size. smaller they are the more damaging they are to humans 

smoke smogs (smoke + fog = smog) 

  • fog formation occurs when cooled moist air reaches dew point - smoke that is part of smog easily inhaled 
  • water vapour condenses as a water layer of airbore droplets - smoke has very high albedo as it reflects light to temp inversion can last for long period of time = increase in pollutant levels 
  • temperature inversions more likley to cause fog formation - does not reach the ground to be absorbed/converted into heat 

thermal inversion: normal warm air from city wll rise, allowing pollutant to escape, on warm days a hot layer can trap cooler air from the city, trapping the pollutants, precipitation can clear air pollutants, wind will disperse it 

effects + imapacts of smoke: 

  • climate: reduce temps due to increased albedo reflectivity, prolonged presence in atmopshere, presence in stratosphere deplete ozone 
  • living organisms: various impacts on humans, synergisms causing secondary pollutants, reduce photosynthesis, contain toxic substances
  • non living organisms: acid rain, damage to hard substrate surfaces, corrosion, rust 

photochemical smog

cities e.g. los angeles prone to photochemical smogs as of traffic pollution, topography + sunny climates + temp inversion are common 

photochemical smog formation: sunlight reacts with (nitrogen dioxide) NOwhihc then interacts with other molecules in air to form smog 


formation of photochemical smog: 

  • haze caused by high levels of atmospheric pollutant primarily ozone + nitrogen oxides, interacting with strong sunlight 
  • on warm sunny days with lots of photochemical smog be formed over cities 
  • fossil fuel combustion 
  • forest buring 
  • frequency + severity of smog depend…


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