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URBAN AIR POLLUTION. Tropospheric Ozone Source: fossil fuel combustion emits two pollutants: - hydrocarbons - nitrogen monoxide Process: nitrogen monoxide reacts with oxygen NO 2 visible brownish colour of the gas: “haze”
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Tropospheric Ozone • Source: • fossil fuel combustion emits two pollutants: • - hydrocarbons • - nitrogen monoxide • Process: • nitrogen monoxide reacts with oxygen NO2 • visible brownish colour of the gas: “haze” • nitrogen absorbs solar radiation breaks down, releasing oxygen atoms combine with oxygen molecules ozone • Effects: • toxic gas and oxidising agent • crop & forest damage, respiration & occular problems
The Colours of Urban Air Pollution • Smoke + fog = industrial smog: • Industrial fossil fuel combustion in humid conditions • grey colour • Vehicle emissions + sunlight = photochemical smog: • vehicle emissions in sunny conditions • brown “haze”
Urban Smog: Los Angeles 25m vehicles 32m people underground limited; doesn’t reach suburbs 4% of population use public transport 182 million km of travel per day average journey to work: 25 mins people travel up to 100kms per day cost of delays (+ extra fuel): $920 per year per driver in LA county / $1100 per driver per year in San Bernardino & Riverside physical factors: landscape: LA basin hemmed by mountains traps pollutants from cars & factories climate: high levels of sunshine photochemical smog formed ozone levels exceed national standard for 100+ days/yr health costs: $10bn on respiratory diseases and cancers
Tackling Tropospheric Ozone Issues Congestion policies restraining use of cars & trucks e.g. Congestion Charge in London, pedestrian zones e.g. High Occupancy Vehicle (HOV) lanes - 480kms of HOV lanes in LA: car pooling policies promoting alternative methods of transport e.g. cycle routes, bus lanes
Air Pollution • Traffic/congestion reduction plans should have knock-on effects to reduce air pollution • Policies for individual vehicles: • conventional petrol vehicles • (e.g. technology to increase efficiency: catalytic converters introduced in USA in 1997) • policies to encourage alternative vehicles • (e.g. development of LEVs & ZEV) • Industrial sources of air pollution = need for further planning/controls: • land use planning: zoning transport & industrial areas • filtration devices • (e.g. electrostatic precipitators: removes particulates • - dust & smoke – from flowing gas using electrostatic charge)
Identify the causes of stratospheric ozone depletion and photochemical smog. • (6 marks) • (b) Explain why some atmospheric pollution issues are regional in effect whereas others are global. (4 marks) • (c) Describe and evaluate pollution management strategies for either global • warming or acid deposition. (8 marks)