6.3 photochemical smog Flashcards
primary pollutants
- pollutants directly emitted from their source
secondary pollutants
- primary pollutants react in the atmosphere and form secondary pollutants
secondary pollutants
acid rain
- nitrogen oxide and sulphur dioxide with water
ozone
- nitrogen dioxide and hydrocarbons with UV
impacts of primary pollutants
carbon dioxide and water vapour
- GHGs, increase average global temperature
sulphur dioxide
- respiratory and eye irritant
- component of acid rain
nitrogen oxides (NOx)
- reduces visibility
- respiratory irritant
- component of acid rain
- precursor of photochemical smog and formation of ozone
formation of photochemical smog
- sunlight activates reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs), forming ozone and peroxyacyl nitrates (PAN).
factors influencing production of photochemical smog
- amount of industry
- population size
- mode of transport used in an area
- high levels of sunlight, more ozone during sunniest part of day
- calm or light winds, reduces dispersion and dilution, pollutants contaminate at ground level
- dry weather, doesn’t wash pollutants out of air
- topography, pollutants accumulate in valley, reduce air flow, tall buildings
thermal inversion layer
- normally air at ground level warms and rises, dissipating pollutants
- air expands and cools, temperature gradient
-thermal inversion, cold air trapped below a warm layer of air, only lasts a few hours
- windless condition, pollutants accumulate at ground level
impact of tropospheric ozone
- highly reactive
- inflammation of lungs coughing, lung disease
- irritates eyes and nose
- damages cells in leaves disrupting photosynthesis
- damages fabrics, rubber and plastic
case study
LA smog
- thermal inversion, valley of LA
- high pollution, sunlight, low winds, not dispersed
- photochemical smog
reduce air pollution
changing human behaviour
- educational campaigns
- individual change, energy efficient devices, turning off when not in use, reduce loss of heat in homes, decrease consumption of nonessential goods, decrease individual car use, hybrid or electric cars
reduce air pollution
economic instruments
- pollution tax, increased for more released
- subsidies for new technology and research
- tax credits, subsidies for using renewable energy sources
- subsidising public transport
- road tolls and parking charges, discourage car use
reduce air pollution
technological changes
catalytic converters
- on motor vehicles
- oxidises carbon monoxide and VOCs
- reduces NOxs
reduce air pollution
+
- increase energy efficiency
- alternative energy sources
- continuing research, low emission transport, renewable energy, efficiency of current products
reduce air pollution
legislation
- set stricter emission standards
- building regulations, efficiency of new and existing buildings, reduce heat loss, more efficient appliances
- planning regulations, place power stations areas least likely to allow air pollution to accumulate
- promote alternatives for private car use
- clean up measures and restoration, scrubbers to clean discharge
case study
beijing
- conditions favourable for the formation of photochemical smog
- large population, high air emissions, poor city visibility
strategy to reduce air pollution
- replace coal burning power stations with gas
- limiting car use to alternative dates depending on license, some people 2 cars
- banning trucks and heavy emissions vehicles
- low number of new cars available for purchace
