Assess air quality impacts
Techniques that analysts, consultants and academics can use to assess the effect of air pollution on human health and the environment.
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Email igcb@defra.gov.uk for:
- feedback on this guidance page and how you have used it for your appraisal
- help with deciding which approach to use in your appraisal
- help using the damage costs toolkit or a request for the toolkit in an accessible format
Understanding the impacts of air pollution
This guidance details the process for assessing the impact on air quality of a policy. You should consider the impact of air pollution in policy making and appraisal where there is potential for air quality impacts, including where polices indirectly result in changes in emissions.
The quality of the air can have an impact on:
- human health and wellbeing
- productivity
- the environment
In 2019, the mortality burden of the air pollution mixture (based on both particulate matter (PM2.5) and nitrogen dioxide (NO2)) in the UK, was equivalent to 29,000 to 43,000 deaths at typical ages. (Source: Chemical hazards and poisons report: issue 28).
In 2019, air pollution was estimated to have an economic cost of £27 billion per year in core healthcare costs and productivity losses with the estimates increasing to as much as £50 billion when wider impacts, such as dementia, are accounted for. (Source: rcp summary for policymakers a breath of fresh air responding to the health challenges of modern air pollution).
Ground-level ozone contributes to environmental harm. In a typical year, ozone reduces crop yields of wheat, potatoes and oilseed rape by approximately 5%. (Source: International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops 2014 to 2017).
National air quality objectives and limits
Concentrations of a range of pollutants in ambient air are regulated by the Air Quality Standards Regulations (AQSR) (2010). The AQSR (2010) set ‘limit values’, ‘target values’, ‘long-term objectives’ and ‘critical levels’ for ambient concentrations of pollutants. For more information go to Air pollution in the UK 2024: compliance assessment summary.
In addition, concentrations of fine particulate matter are regulated by more recent legislation which came into force in January 2023: the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 (UK Government, 2023).
Consider whether your policies are likely to result in a breach of any regulations. If they are, take mitigating action to prevent a breach and also assess the impact of the breach using this guidance.
Consider appropriate abatement measures and understand the potential costs involved, including whether there are local issues to take into account. If you need help quantifying abatement measures, email Defra igcb@defra.gov.uk.
Further information:
- for guidance about general appraisal methodology, go to the HM Treasury Green Book
- for information about the application of this guidance for transport policies, go to DfT’s Transport Appraisal Guidance (TAG), specifically the TAG data book Table A3.2 (TAG data book - GOV.UK) and Section 3 of the TAG unit A3 environmental impact appraisal (Tag unit A3 environmental impact appraisal)
- for data on the ‘activity costs’, go to DESNZ’s Green Book supplementary guidance: valuation of energy use and greenhouse gas emissions for appraisal. Specifically Table 14 and Table 15 of the data tables (data-tables-1-19.xlsx)
- for a detailed report on the damage costs update, go to the 2025 damage cost report