Why the UK needs a national guide to air quality design

A national guide to air quality design, setting out good air quality design principals for new planning developments, is vital if the UK is to reduce urban air pollution and meet housing targets, says Guido Pellizzaro.

Guido Pellizzaro
22 April 2019

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Currently in the UK there is no concise checklist of air quality design principals that urban planners should be adhering to when in the design stages of a new development.  

At the highest strategic level, the National Planning Policy Framework states that opportunities to improve air quality or mitigate air quality impacts should be identified at the plan-making stage. Yet no further assistance is provided on the air quality design measures the government is seeking. It is left open for urban designers, consultants and local authorities to use professional judgement on what is deemed appropriate, often leading to conflict between individuals.

Given this conflict, there has been an increase in the refusal of planning applications based on air quality grounds. Such as the case law of Wealden Council vs SoS + Knight Developments whereby the developer for a residential development was unable to define a scheme of mitigation for nitrogen deposition to protect the sensitive ecological habitat of the Ashdown Forest and therefore the application was refused. Similarly, the case law for Gladman Developments vs SoS, Swale Borough Council & CPRE saw the refusal of planning permission for a residential development due to a lack of evidence regarding mitigation in an air quality management area. 

"In areas already exceeding air quality standards, even a small increase in air quality could result in planning refusal as the development could be seen as being non-compliant or delaying compliance with air quality standards."

In general terms, developments by their nature can increase traffic by attracting new users, and the servicing of new uses. In addition, developments can release emissions through new energy and heating combustion plants. In areas already exceeding air quality standards, even a small increase in air quality could result in planning refusal as the development could be seen as being non-compliant or delaying compliance with air quality standards. Case laws have now set the precedent for this refusal.

To enable the granting of planning permission, local planning authorities are requesting that the effect of air quality mitigation is quantified (in µg/m3) in order to demonstrate how mitigation will translate into actual air pollution reductions. However, there is a lack of evidence to enable the success of non-vehicle and non-combustion emissions mitigation to be quantified. 

Sustainable transport provisions such as walking incentives and cycling routes are based on behavioural characteristics. But how can the success of such walking and cycling incentives be accurately quantified, especially when behavioural changes might change from day to day (e.g. a person may decide to drive rather than cycle on a rainy day). Furthermore, the success of green infrastructure (e.g. a wall covered in ivy beside a road) is site-specific, based on factors such as local dispersion characteristics. To add complexity, what is considered as acceptable air quality mitigation can differ between neighbouring local authorities. 

What is required is a national guide to air quality design. This would ensure all developments include good air quality design, endorsed at the national and local level, which could avoid planning refusal due to a lack of quantifiable evidence on air quality mitigation. A national design framework could reduce urban air pollution and would provide an opportunity for the UK to improve air quality in the shortest timescale possible. Importantly it would reduce professional conflicts and allow the UK to continue to meet housing targets.

Guido Pellizzaro is associate director for air quality at Waterman Infrastructure and Environment.