URBAN AIR POLLUTION Tropospheric Ozone Source fossil fuel

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” • 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”

25 m vehicles Urban Smog: Los Angeles 32 m 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 100 kms 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: $10 bn 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 - 480 kms 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)

(a) 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)