CGP Urban Air Quality

• Particulates


  Tiny pieces of solids and tiny droplets of liquids floating in the air
• More particulates are found in urban areas than in rural areas. The concentration of particulates in urban areas is around 10-40 μg/m3, compared to less than 10 μg/m3 in rural areas
• Sources of particulates

  • Vehicle exhausts (produce very fine particulates 0.01 μm-10μm)
  • Burning of refuse, cigarettes and fuel (produces fine and coarse particulates, e.g. sulfates, nitrates, soot and ash)
  • Construction, mining and quarrying (produce coarse particulates 10 μm-100 μm, e.g. tiny fragments of rock, brick and cement dust)
  • Plants and moulds (generate coarse particulates, e.g. pollen and mould spores)
• Particulates

  • Coarser particulates are usually filtered out by the nose and throat, but finer particulates less than 10 μm in diameter (often called PM10) can enter the lungs
  • PM10 could cause or make worse problems like asthma, bronchitis, lung cancer and heart disease
• Photochemical pollution

  • Pollutants such as nitrogen oxides, sulfur oxides and hydrocarbons come from burning fossil fuels (e.g. in vehicles and factories)
  • When these pollutants come into contact with sunlight, the UV light causes them to break down into harmful chemicals (e.g. ozone) which form photochemical smog
• Photochemical smog is a problem in many cities, e.g. Los Angeles (USA), Beijing (China), Mexico City (Mexico) and Barcelona (Spain). It's more common in places with hot and sunny climates because there's more sunlight
• These locations often have a temperature inversion (a layer of warm air trapped below denser cooler air), which keeps the pollutants at ground level
• Photochemical smog


  • It's linked to health problems such as breathing difficulties, coughing, shortness of breath, respiratory disorders (e.g. asthma) and headaches
• Ways to reduce air pollution

  • Congestion charging
  • Pedestrianisation
  • Public transport improvements
  • Other schemes for reducing traffic
  • Legislation (laws)
  • Alternative fuels
• Congestion charging

  • People are charged if they use their vehicles in certain places at certain times
  • This reduces pollution by reducing road traffic
• Pedestrianisation

  • Vehicles are restricted from entering certain places at certain times
  • It reduces pollution by reducing road traffic
• Public transport improvements

  • Encouraging people to use public transport instead of their cars reduces pollution
  • Examples: improved bus services, bus lanes, park and ride schemes, trams and light railway services
• Public transport improvements are often expensive - e.g. construction of the Metrolink in Manchester took about 26 years
• Other schemes for reducing traffic


  • Banning cars with certain number plates from being used on certain days
  • Council-run car sharing schemes
• Legislation (laws)

  • Laws aim to reduce pollution by limiting emissions and setting air quality standards
  • Examples: UK Clean Air Acts, Road Vehicles Regulations, local authority powers to issue fines
• Alternative fuels

  Petrol and diesel are replaced with cleaner fuels that pollute less, e.g. biofuels, liquefied petroleum gas (LPG), electric vehicles
• Growing crops for biofuels can reduce biodiversity, e.g. biofuels like corn-based ethanol require a lot of land to grow, which means clearing other vegetation
• What are particulates?

  Tiny pieces of solids and tiny droplets of liquids floating in the air