Tetra Tech’s Kathryn Barker, air quality specialist, outlines interim planning guidance for meeting particulate matter targets under the Environment Act and what planners must consider to support compliance.
In 2025, the Department for Environment, Food, and Rural Affairs (Defra) published interim planning guidance related to the Environment Act Particle Matter (PM2.5) targets.
While this guidance is distinct from how PM2.5 emissions should be considered in environmental permitting, it is important for the planning regime across England. In this article, Kathryn outlines how developers can ensure that new projects align with the requirements of this latest air quality planning guidance.
About the targets
PM2.5 consists of fine particulate matter, including construction dust, combustion particles, organic compounds, and metal fragments, with a diameter of 2.5 µm or less. Common sources of PM2.5 include vehicle emissions, industrial processes, combustion sources, and construction sites. Exposure to PM2.5 can lead to or exacerbate respiratory issues and cardiovascular diseases.
What are the targets?
The Air Quality Standards Regulations (2010) set a limit value of 20 µg/m³, expressed as an annual average, for PM2.5.
However, the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 establish two new targets for PM2.5 to be achieved by 2040:
- A maximum annual mean concentration target of 10 µg/m³; and
- A population exposure reduction target of 35% compared to 2018.
Purpose of the updated guidance
The purpose of these targets is to improve air quality by reducing PM2.5 levels nationwide, thereby helping to safeguard public health. While the achievement of these targets will be assessed at relevant monitoring sites, they apply to ambient (outdoor) air throughout England. Applicants and Local Planning Authorities must consider the impact of developments on air quality in all ambient air, regardless of whether a monitor is present.
These targets necessitate a shift in approach for applicants and Local Authorities, moving away from merely assessing whether a scheme might exceed a legal limit. Instead, they emphasise the implementation of appropriate mitigation measures from the design stage, streamlining the planning process, and minimising pollution emissions while reducing exposure.
Key considerations when applying the new guidance
The interim guidance applies to future developments that have the potential to emit or are sensitive to PM2.5. It does not apply to planning decisions for applications submitted before 4 October 2024.
The guidance emphasises the importance of implementing appropriate mitigation measures during the design stage of new developments to minimise both PM2.5 emissions and exposure, rather than solely assessing the likelihood of exceeding the limit value.
Applicants must provide evidence in their planning applications that they have identified key sources of PM2.5 within their schemes and taken reasonable actions to minimise emissions of PM2.5 and its precursors.
Exposure to PM2.5 is particularly critical for highly sensitive uses, such as residential, educational, childcare, and healthcare facilities. Developers should consider the location of polluting development sites in relation to existing sensitive receptors, as well as the placement of sensitive uses within the new development site concerning nearby PM2.5 sources.
Questions to consider for new developments:
Is the new development a potential source of PM2.5 during construction and/or operation? If so:
- Can the new development site be located away from existing sensitive receptors, such as large residential communities, schools, hospitals, and care homes?
- Can potential new sources of PM2.5 within the new development site be positioned as far away as possible from neighbouring sensitive receptors?
- Can mitigation measures be implemented within the new development to reduce or eliminate PM2.5 emissions?
Is the new development sensitive to exposure to PM2.5? If so:
- Can the new development site be situated away from local sources of PM2.5?
- Can the proposed sensitive uses be located as far away as possible from neighbouring sources of PM2.5?
- Can mitigation measures be implemented within the new development to reduce or eliminate exposure to PM2.5?
How our air quality experts can help
This article serves as a starting point for developers to consider Defra’s new interim planning guidance regarding the Environment Act PM2.5 targets. The key to identifying ways to reduce exposure to and emissions of PM2.5 lies in collaboration with essential project team members, such as air quality consultants, transport consultants, architects, and energy and sustainability experts.
Our experts have conducted Air Quality Assessments for numerous new developments over the past few years, covering various use classes and routinely addressing PM2.5 emissions and exposure. We also have extensive experience collaborating with project teams to provide site-specific air quality measures and advice to mitigate emissions and exposure.
About the author
Kathryn Barker
Kathryn Barker is an air quality consultant specialising in air quality, odour, and dust assessments.
She has over 10 years experience supporting planning and permitting applications across a range of sectors including residential, commercial, renewable energy, waste facilities, data centres, industrial installations, power generation, short-term operating and carbon capture facilities. She has prepared assessments to support EIA and DCO developments and undertaken monitoring of dust, air quality, and odour.
She has an MSc is Environmental Pollution Control from the University of Southampton and a BSc (Hons) in Environmental Science from the University of Leeds. She is a member of the Institute of Air Quality Management and the Institution of Environmental Sciences.