1. URBAN AIR POLLUTION

3. 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

6. 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”

7. 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

8. 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

9. 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)

10. 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)