When is an air quality assessment needed?
Clean air isn’t a luxury — it’s a basic need. Yet, in the UK planning system, air quality still too often becomes an afterthought.
When Is an Air Quality Assessment Needed?
Air quality plays a vital role in protecting health and creating sustainable communities. For developers, planners, and architects, knowing when an Air Quality Assessment for planning permission is required can mean the difference between a smooth planning process and unexpected delays.
At Haze Environmental, one of the most common questions we’re asked as air quality consultants is:
“Does my project really need an air quality assessment?”
The answer depends on both the scale of your development and the local air quality context.
Why Air Quality Matters in Planning
According to the World Health Organization (WHO), nearly everyone on the planet is breathing air that exceeds safe pollutant levels. The health risks are serious — from asthma and respiratory illness to cardiovascular disease, stroke, and even certain cancers.
In 2020, the UK reached a landmark moment when air pollution was listed as a cause of death on a child’s death certificate — a tragic but vital recognition of its very real dangers.
The Royal College of Physicians’ latest report also highlights that air pollution doesn’t affect everyone equally. Children growing up in deprived urban areas are more likely to breathe polluted air and to live with pre-existing health conditions that make exposure even more harmful.
In the UK, air quality is a material consideration in the planning system, meaning decision-makers must take it into account when approving developments. Not every scheme needs an assessment, but if a project could worsen local air quality or expose people to harmful pollution, an air quality assessment becomes essential.
Breathing clean air:
- Reduces inflammation in the lungs, helping to prevent or reduce the severity of asthma attacks.
- Improves overall lung function, particularly in children and older adults.
- Lowers the risk of chronic conditions such as COPD and cardiovascular disease.
- Supports recovery for those with existing respiratory illnesses.
Innovative urban design plays a key role in tackling air pollution. Effective partnerships between developers, policymakers, and communities are essential to accelerate sustainable solutions.
In London, initiatives such as Air Quality Positive demonstrate how air quality can — and should — be embedded throughout the entire project life cycle, rather than treated as an afterthought.
On a recent residential scheme our air quality consultants worked on, early screening revealed elevated background NO₂ levels — allowing the design team to adapt layouts before planning submission.
Key Triggers for an Air Quality Assessment
You’ll typically need an assessment if your project meets one or more of these thresholds:
- Residential developments with more than 10 homes
- Non-residential developments with over 1,000 m² of floor space
- Sites larger than 0.5 hectares
- Schemes with more than 10 parking spaces
- Developments including a centralised energy facility (e.g. CHP plant, biomass boiler)
- Projects likely to cause significant changes in traffic flows, such as a new road layout or a large increase in vehicle movements.
With the release of the most recent WHO air quality guidelines, Local Authorities are becoming stricter — moving beyond basic compliance with national standards and taking a more proactive stance on air quality.
Local Environmental Context
Even smaller schemes may trigger the need for an AQA if:
- The site lies within or close to an Air Quality Management Area (AQMA)
- The background pollution levels are already high
- Sensitive uses are introduced (e.g. homes, schools, healthcare facilities) near busy roads or industrial sources
In these cases, an assessment helps determine whether future occupants would be exposed to harmful pollution and identifies what mitigation measures may be needed.
When working on schemes in London, consultants must also consider Air Quality Focus Areas, as well as Air Quality Neutral and Air Quality Positive guidance. These frameworks reflect the growing emphasis on designing developments that not only minimise emissions but actively contribute to cleaner air.
Best Practice: Engaging Early
The best way to avoid unnecessary costs and delays is to engage early with your Local Planning Authority (LPA) and an air quality consultant.
A phased approach often works best:
- Screening Assessment – a quick check to see if an AQA is required.
- Detailed Assessment – if needed, modelling and monitoring provide a full picture of potential impacts.
This ensures you only invest in detailed work when it’s genuinely necessary.
With over 18 years of consultancy experience, I’ve found that air quality is often treated as an afterthought — although this is thankfully starting to change. The risk of leaving air quality to the last minute can be costly: late-stage design changes or retrofits can quickly escalate budgets.
When air quality is integrated as part of a holistic design approach, schemes run more smoothly and deliver better outcomes for both people and the environment. Considering air quality early isn’t just good practice — it’s smart planning.
Final Thoughts
One of the biggest misconceptions developers have about air quality assessments for planning permission is underestimating their importance within the planning process.
At Haze Environmental, we aim to change that perception — helping clients understand that considering air quality early adds value beyond compliance. With Local Planning Authorities increasingly moving beyond national standards, now is the time for developers to take air quality more seriously.
An Air Quality Assessment isn’t always required, but when it is, it can be critical for securing planning approval and protecting public health. If you’re unsure whether your development falls into that category, seeking advice early can save both time and money.
At Haze Environmental, we help developers, planners, and architects navigate this process with clear, robust assessments tailored to each project’s needs.
Not sure if your development needs an Air Quality Assessment? Get in touch with us today at airquality@hazeenvironmental.com
About Haze Environmental
Haze Environmental is an independent air quality and odour consultancy on a mission to make a positive impact on the clients we work with — and on the environment we all share.
