Understanding the Updated IAQM Guidance on Dust Assessment

The Institute of Air Quality Management (IAQM), the professional body for air quality consultants in the UK, recently updated their Guidance on the assessment of dust from demolition and construction. This guidance is widely referenced in air quality assessments across the UK, explaining how construction dust risk assessments are undertaken and what constitutes an appropriate level of dust mitigation. The update will change the assessed dust risk of some construction projects, influencing the type of dust mitigation and monitoring developers and contractors will be required to employ to adhere to best practice.

For those involved in planning applications and building works, it is crucial to understand the implications of these revisions. In this short article, we will delve into the key changes and their potential impact on developers and contractors.

Key Changes in the Updated IAQM Guidance
The most significant amendment in the updated IAQM guidance is the redefinition of the ‘dust emission magnitude’ categories for demolition, earthworks, construction, and trackout. These changes aim to provide a more accurate assessment of dust emissions. Here is a comparison of the changes:

Phase	2014 Guidance	2023 Guidance
Demolition	Large: Total building volume >50,000 m³ Medium: Total building volume 20,000 m³ – 50,000 m³ Small: Total building volume <20,000 m³	Large: Total building volume >75,000 m³ Medium: Total building volume 12,000 m³ – 75,000 m³ Small: Total building volume <12,000 m³
Earthworks	Large: Total site area >10,000 m² Medium: Total site area 2,500 m² – 10,000 m² Small: Total site area <2,500 m²	Large: Total site area >110,000 m² Medium: Total site area 18,000 m² – 110,000 m² Small: Total site area <18,000 m²
Construction	Large: Total building volume >100,000 m³ Medium: Total building volume 25,000 m³ – 100,000 m³ Small: Total building volume <25,000 m³	Large: Total building volume >75,000 m³ Medium: Total building volume 12,000 m³ – 75,000 m³ Small: Total building volume <12,000 m³
Trackout	Large: >50 HDV (>3.5t) outward movements in any one day Medium: 10-50 HDV (>3.5t) outward movements in any one day Small: <10 HDV (>3.5t) outward movements in any one day	Large: >50 HDV (>3.5t) outward movements in any one day Medium: 20-50 HDV (>3.5t) outward movements in any one day Small: <20 HDV (>3.5t) outward movements in any one day

Practical Implications
To illustrate the practical implications of the revised guidance, let’s consider an example: the demolition of a 15,000 m³ building in the city of Chelmsford on a 1-hectare plot of land. Under the previous guidelines, this would have resulted in a Small dust emission magnitude for demolition and a Large emission magnitude for earthworks. However, the 2023 guidance, acknowledging the greater concern posed by demolition activities, classifies the dust magnitude associated with demolition as Medium and earthworks as Small.

These shifts may lead to a higher proportion of developments being categorized as presenting a Medium risk of dust soiling. In cities, such as London, Chelmsford, Colchester, Cambridge and Norwich and many other other urban areas, dust management plans (either standalone or part of a Construction Environmental Management Plan) are often required for developments that present a Medium risk. Medium risk projects are also normally required to carry out continuous particulate monitoring (PM10/PM2.5). As councils can request baseline monitoring of up to 3 months prior to any construction work taking place, these changes could have significant impacts on the timelines of some projects.

Detailed Assessments and Health Implications
The updated IAQM guidance also provides clarity on the level of detail required in dust risk assessments for different planning application types. For Outline Permission applications, where limited information regarding construction methods may be available, an initial screening dust assessment is recommended. At a later planning stage, whether for full permission or associated with planning conditions, the updated guidance dictates that a detailed assessment should be conducted, considering the development’s scale and precise distances from dust sources to receptors.

The Essex Design Guide emphasizes the importance of addressing air pollution at both the design and construction stages. It outlines a hierarchy for addressing air pollution, starting with the avoidance of emissions, followed by reduction and mitigation measures [1]

This approach aligns with the IAQM’s updated guidance, ensuring that health risks associated with PM2.5 are comprehensively addressed.
The recent guidance update reflects the latest knowledge about the health effects of PM2.5. These ultra-fine particles can enter our bloodstream and have a significant impact on our health. The revisions in the guidance were made to ensure that these health risks are addressed comprehensively, acknowledging the evolving understanding of PM2.5 and its implications on public health.

Conclusion
If you would like to discuss how changes to the IAQM’s Guidance on the assessment of dust from demolition and construction may impact your construction project, please do not hesitate to get in touch.
[1:] Essex Design Guide – Air Quality

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