Assess the impact of air quality
Techniques that analysts, consultants and academics can use to assess the effect of air quality on human health and the environment.
Documents
Details
This guidance outlines how you can work out the effects of air pollution within economic appraisals.
For guidance on general appraisal methodology see the HM Treasury Green Book.
Select a technique
Use the toolkit to calculate the net present value of the change in air pollution for your scheme. This toolkit uses the damage costs approach.
The impacts are less than £50 million
If the impacts are less than £50 million in total, then continue to use the calculated values from the toolkit. Use the damage costs approach guidance to:
- value the changes in air pollution in a ‘light touch’ way within your own modelling
- understand the methodology of the toolkit
‘Damage costs’ are the health impact on society of a change in emissions of different pollutants.
To make sure you have interpreted the toolkit correctly, read the damage costs approach before including air pollution analysis within your appraisal.
The impacts are more than £50 million
If the impact is more than £50 million, or the main objective of the policy or project is changes in air quality, use the impact pathways approach. The impact pathways will value the impacts of air pollution where they are ‘localised’ - that is focused in one specific area, for example, the impact of emissions around a specific power station.
Air pollution levels and research
For more information on air pollution levels and further research, go to the UK-AIR website.
Email igcb@defra.gov.uk for:
- help with deciding which methodology to use in your appraisal
- help with the toolkit
- more information on air quality techniques
- the toolkit in an accessible format
Call: 0800 032 7953
Air quality economics
Environment Quality
Department for Environment, Food and Rural Affairs (Defra)
Ground floor, Seacole Building, 2 Marsham Street
London
SW1P 4DF
Last updated 2 March 2023 + show all updates
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Corrected the figure for the high value for PM2.5 for rail transport inner London on table 10 of "Air quality appraisal: damage cost guidance". This value is £1,109,872.
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On the damage cost guidance - changed the mortality burden of air pollution mixture from '28,000 to 36,000' to '29,000 to 43,000'.
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Updates made to the information and data on 'Air quality appraisal: damage cost guidance' and 'Air quality appraisal: impact pathways approach' and uploaded an updated version of 'Air quality appraisal: damage costs toolkit'. The format of some of the tables have also been changed to make them easier to read.
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Air quality damage cost appraisal toolkit updated.
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Updated '2019' to '2020' in these instances: Annex A: updated 2020 damage costs. Introduction: 2020 damage costs. 1.1 Title Table 1: 2020 damage cost values …appraisal period starts in 2020 …should first be uplifted to 2020. Changed '2021' to '2022' in Section 3.1 after "tonnes per year".
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Values in Table 8 'contribution of different impact pathways to overall national damage costs' in impact pathway guidance publication updated.
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New air quality appraisal toolkit. Updated damage cost guidance with new values in these tables and steps, now showing 2020 to 2029 instead of 2019 to 2028: Table 1: 2020 damage cost values Table 3: level of change in NOx emissions Table 4: change in emissions (t) with appropriate damage cost (£) Table 5: change in emissions, appropriate damage cost and rebased damage cost Table 6: annual uplift factors being applied to the rebased damage costs Table 7: calculating the total annual benefit of the change in emissions Step 6: discount benefits across the period of the policy appraisal to calculate total present value Table 8: total benefits of the change in emissions Step 7: sensitivity analysis Table 9: total discounted benefits - high sensitivity Table 10: updated full set of damage costs
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First published.