Technological solutions
Big idea: Technology can reduce emissions at the source — through cleaner vehicles, improved industrial processes, and cleaner energy generation.
Vehicle technologies
- Catalytic converters: Convert CO, NOₓ, and hydrocarbons to less harmful gases — required on petrol cars since 1970s/80s
- Particulate filters: Trap soot from diesel exhausts
- Electric vehicles (EVs): Zero tailpipe emissions (but electricity source matters)
- Hybrid vehicles: Combine engine and electric motor for better efficiency
- Hydrogen fuel cells: Zero emissions; water is only byproduct
Industrial and energy technologies
- Scrubbers: Remove SO₂ and particulates from power plant emissions
- Electrostatic precipitators: Remove particulates using electrical charge
- Low-NOₓ burners: Reduce nitrogen oxide formation during combustion
- Fuel switching: Move from coal to natural gas or renewables
- Carbon capture: Remove CO₂ (primarily for climate, but some co-benefits)
Domestic solutions
- Clean cookstoves: Reduce indoor air pollution from biomass burning
- Efficient heating: Modern boilers, heat pumps, insulation
- Cleaner fuels: Switch from coal/wood to gas or electricity
Exam tip: Technological solutions are often favoured by technocentric EVSs. Be ready to evaluate their effectiveness AND limitations (cost, rebound effects, addressing symptoms not causes).
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Policy and behavioural approaches
Big idea: Regulations, economic incentives, and behaviour change can complement technology by reducing emissions and encouraging cleaner choices.
Regulatory approaches
- Emission standards: Set limits on what vehicles and industry can emit
- Air quality standards: Define acceptable pollution levels (WHO guidelines, national standards)
- Vehicle restrictions: Low emission zones (LEZs), congestion charging, car-free days
- Industrial permits: Require pollution control as condition of operating
- Fuel quality standards: Mandate low-sulfur fuels, ban leaded petrol
Economic instruments
- Congestion charges: Fee for driving in city centres (London, Singapore, Stockholm)
- Pollution taxes: Tax on emissions or polluting fuels
- Subsidies: Support for EVs, public transport, clean technology
- Scrappage schemes: Incentives to replace old, polluting vehicles
- Cap and trade: Market-based limits on industrial emissions
Behavioural and planning approaches
- Public transport investment: Provide alternatives to private cars
- Cycling and walking infrastructure: Safe routes, bike-sharing schemes
- Urban planning: Mixed-use development reduces travel; green spaces improve air quality
- Awareness campaigns: Educate public about pollution and health
- Remote working: Reduce commuting (accelerated by COVID-19)
Londons congestion charge reduced traffic by 30% and improved air quality in the charging zone. Economic instruments can be highly effective.
Exam tip: Compare TECHNOLOGICAL vs BEHAVIOURAL approaches. Technocentrists favour technology; ecocentrists often prefer demand reduction and behaviour change.
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IB-style question — Managing urban air pollution [4]
Mardelo's council wants to cut the city's fine-particle (PM2.5) levels.
Describe four strategies that could be used to reduce air pollution in the city. [4]
How to answer it, step by step
- Cut the emissions at source
• Reduce traffic: odd–even plates, low-emission zones, electrify buses
• Switch heating from coal/wood to clean electricity or gas - Clean up + manage what's left
• Fit catalytic converters/filters; plant trees and green roofs to absorb particles
• Public-awareness campaigns and air-quality alerts on high-pollution days
Final answer
Examiner tip: 'Describe four' wants four distinct strategies, each with a short 'how it works'. Spread them across transport, energy and green infrastructure so the points clearly differ.
IB-style question — Managing urban air pollution [1]
After Mardelo launched a clean-air plan, average winter PM2.5 fell from 45 µg m⁻³ to 27 µg m⁻³.
Calculate the percentage reduction in PM2.5 concentration. [1]
How to answer it, step by step
- Set up the percentage-change formula
• % change = (change ÷ original) × 100
• Change = 45 − 27 = 18 µg m⁻³ - Substitute and solve
• (18 ÷ 45) × 100
• = 40% reduction
Final answer
Examiner tip: always divide the change by the ORIGINAL value (45), not the new one. Show the subtraction and the division so a correct method can still earn the mark.