What are odour assessments and how are they carried out?

What is an odour assessment?

An odour assessment is a process used to evaluate and measure the presence of smells (or odours) in a specific area. It helps identify the frequency, intensity, duration, unpleasantness and location of a given odour source. These are knownas the ‘FIDOL’ factors. While all odour assessments aim to determine the significance of odour impact and loss of amenity, the scope and complexity of these assessments can vary depending on the scale and nature of the process in question.

It is essential that odour assessments consider the FIDOL factors and follow relevant guidance such as published by the Institute of Air Quality Management [1] (IAQM) and/or the Environment Agency [2] (EA).

Why are odour assessments required?

In the UK, odour is principally regulated by National and Local Planning Policy, the Environmental Permitting Regulations, and the Environmental Protection Act 1990.

Whilst odour assessment is not universally mandated as a statutory requirement in the UK, they do play a significant role in various permitting and planning processes in order to manage nuisance and the associated disamenity across a range of industries such as waste management, animal processing, food processing and waste water treatment.

In the context of planning, odour assessments are often seen as a necessity in the eyes of the Local Planning Authority (LPA) if you are introducing an additional odour source to a local community where people are present OR if you are introducing additional people to an environment where adverse odour emission might be present. Either way, the main aim of an odour assessment is to establish the level of nuisance or disamenity caused to people living and working in a given area.

In the context of permitting, odour emissions from major sources are tightly regulated and often require odour assessment as part of your environmental permit. Assessment can be born out of number of reasons, including but not limited to an influx in odour complaints from the local community, Improvement conditions put forward by the EA in relation to your environmental permit and the addition of further processes / expansion of existing processes.

Overall, odour assessments help ensure the impacts of odorous emissions are adequately managed and mitigated, protecting the quality of life for local residents.

How are odour assessments carried out?

The approach by which odour assessment is undertaken should be proportionate to the scale and nature of the process in question, as well as the specific requirements of the LPA or EA. In general, odour assessments can be divided into ‘simple’ assessments and ‘detailed’ assessments. It is also recommended (by the IAQM), and reflects best practice to adopt a “multi-tool” assessment approach; whereby a combination of assessments methods are utilised.

Simple Assessment

A simple odour assessment will typically include:

• A desk based qualitative assessment of odour impact utilising the Source-Pathway-Receptor (SPR) conceptual model; and
• Olfactory field surveys (’sniff testing’) in accordance with IAQM guidance to ‘calibrate’ to the SPR model.

Detailed Assessment

Detailed odour assessment will typically include all aspects of a simple assessment, with the addition of:

• Odour monitoring – typically undertaken during worst case conditions;
• Quantitative odour dispersion modelling – utilising the collected odour monitoring results as input into the modelling; and
• Odour complaints analysis (where applicable).

How can SLR help with odour assessments?

SLR provides a comprehensive suite of services in relation to odour including the following:

• Olfactory field surveys (‘sniff testing’);
• Odour monitoring;
• Qualitative Source-Pathway-Receptor (SPR) sssessment;
• Quantitative odour dispersion modelling;
• Best Available Techniques (BAT) assessment;
• Odour abatement design and tender management;
• Odour Management Plans (OMPs);
• Odour risk assessment for commercial kitchens;
• Complaints analysis;
• Peer review of existing ddour sssessment; and
• Expert witness

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References

[1] Guidance on the assessment of odour for planning. Version 1.1 - July 2018.

[2] H4 Odour Management. How to comply with your environmental permit. March 2011.