The 2021 Environment Act and subsequent Environmental Targets Regulations 2023 in relation to fine particles (PM2.5) mean that air quality assessments in the UK are likely to change soon. This will have implications for planning applications and could affect your development. Nick Hawkins explains all.
What is changing?
Many planning applications in the UK, especially in urban areas, require air quality assessment reports to accompany the application to determine both the impact of the proposed development, as well as to determine whether the air quality on site is appropriate for its intended use. For example, air pollution concentrations on potential residential development sites are compared to the National Air Quality Objectives and if pollution targets are expected to be exceeded, mechanical ventilation may be required to mitigate against the pollution, or at worst, it could mean that the site is undevelopable.
In recent years, the shifting focus of concern in relation to air quality has been in relation to fine particles or PM2.5. Under the 2021 Environment Act, this required long-term targets to be set for fine particulate matter. These were then set under the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 which can into force in January 2023.
Currently, if a development site has concentrations of PM2.5 in excess of 20 µg/m3 it would be considered to have poor air quality. In reality, very few locations in the UK have concentrations of PM2.5 in excess of this level, so this is not normally an issue. However, under the new regulations this will be lowered to 10 µg/m3. This, however, will be much more difficult to achieve, with most of Greater London and the centres of many towns and cities across the UK currently exceeding this level.
The new regulations state that these levels don’t need to be achieved until 2040 and with pollutant concentrations decreasing across the UK, especially considering the phasing out of diesel and petrol cars over the next 10 years, this does not necessarily mean that sites that currently exceed 10 µg/m3 of PM2.5 will be problematic in future.
The new targets also state that there needs to be a 35% reduction in population exposure by 2040 (compared to a base year of 2018). Therefore, there will be an even greater incentive for Councils to refuse planning applications for developments in area of poor air quality.
How will this change Air Quality Assessments?
At present, air quality assessments consider the baseline year (normally the latest year for which local air quality monitoring data is available), then make future predictions of air pollution for the opening year of the development, i.e. the year when people are expected to move in, which for small to medium sized developments is often only a year or two in the future. However, in future, air quality assessments will need to start considering pollutant concentrations on a development site in 2040. Therefore, environmental consultants such as Hawkins Environmental will need to start making future predictions of air pollution for the year 2040 on the development site. If concentrations of PM2.5 are predicted to exceed 10 µg/m3 in 2040, mitigation needs to be put in place to ensure that residents are not exposed to harmful levels of pollution.
This means that instead of modelling two years, environmental consultants will have to model three years, plus could mean that some sites could be classed as having poor air pollution, which otherwise would be considered perfectly acceptable.
When will this happen and why aren’t we doing this now?
When will this happen – good question – the honest answer is we don’t know, but it is likely to be sometime this year. The problem is that whilst the new regulations exist and have already come into force, the tools required to determine compliance have yet to be published by Defra.
To model air pollution, a range of tools are used, provided by Defra. These include the Emissions Factor Toolkit (which allows the calculation of road vehicle pollutant emission rates for a specified year) and mapped background concentrations (which provides estimates of background concentrations of all pollutants across the country for any given year). However, all of these tools are year specific, i.e. they can only be used to model specific years. The problem is that until recently, all of these tools only worked until 2030, i.e. they could not be used to model pollutant concentrations beyond the the year 2030.The ability to accurately model pollution concentrations in 2040 is essential for determining whether the new National Air Quality Objective for PM2.5 will be met on a site or not.
In December 2023, Defra published Emissions Factor Toolkit EFT v12, will emission outputs until the year 2050. This data now takes into account the ban on petrol and diesel cars from 2035 and also London’s ULEZ. However, Defra have yet to update other tools, such as the background maps. Hawkins Environmental approached Defra for comment regarding the background maps. Defra acknowledge that they are currently being updated, but no publication date has been announced. However, Defra have stated that it should be sometime in 2024.
So this doesn’t really matter yet?
Yes, and no. At some point in the future, the Defra tools (and specifically the background maps) will be updated and it is likely that from that point, all Councils will expect air quality assessments to consider future PM2.5 concentrations. The problem is that air quality assessments are prepared in advance of planning applications and can take weeks or even months from the date of submission for them to be reviewed by Environmental Health Officers. Given the new regulations are already in force, it is likely that Environmental Health Officers will expect air quality assessments for developments already in the system to be updated to take into account the new PM2.5 targets as and when the methodology allows. Therefore, it is possible that air quality assessment that have already been prepared may need updating.
Does this mean that developments could fall foul of the changes?
Potentially yes and this is the biggest issue. There is at least the potential that development sites that meet the current National Air Quality Objectives, may fail to meet the PM2.5 target for 2040. Therefore, it is possible that overnight, a site that would otherwise be considered of no concern, could become an issue in terms of the PM2.5.
The problem is that it will be very difficult to pre-empt the change. The tools don’t exist to accurately model air pollution beyond 2030 in the UK, so it is difficult to accurately speculate in relation to future pollution concentrations. The underlying background concentrations in an area have the greatest contribution to ambient PM2.5 levels. Therefore, the amount Defra forecasts background concentrations will decrease by will be critical. Whilst we know that background concentrations of PM2.5 are decreasing and will continue to do so, the rate by which they decrease between now and 2040 is not defined, especially considering recent changes in policy to improve air pollution.
Overall, whilst the tightening of PM2.5 target values is of course a welcome improvement to our environment and public health, the uncertainty it leaves could cause problems with future development.
Nick Hawkins is Managing Director of Hawkins Environmental Limited, an Urban Environmental Consultancy. Nick has 20 years of experience in the field of acoustics, air quality and daylight assessment.