Odour Impact Assessment

Odour Impact Assesment

An Odour Impact Assessment or Odour Assessment is an important condition of planning focusing on the evaluation of potential risk of odour annoyance to residents and businesses in the local area.

The Institute of Air Quality Management (IAQM) guidance defines odour as a mixture of many chemicals which interact to produce a ‘smell’. ‘Odour-free air’ refers to air containing no odorous chemicals. Fresh air is usually perceived as air containing no chemicals or contaminants that could be identified as ‘unpleasant’. Odour however is not strictly speaking an air pollutant.

An odour emission can cause annoyance and have an adverse impact on surrounding areas, resulting in complaints, investigation, and enforcement action from Environmental Health Officers from the Local Authority. A Combination of chemicals can affect the olfactory response causing a loss of amenity. Odour is subjective to the individual who determines whether it is acceptable, objectionable, or offensive.

The potential of odour impact on surrounding areas often causes an Environmental Health Officer and Local Planning Officers request the submission of an Odour Impact Assessment either prior to planning or as a condition of planning.

Odour can be produced from several industries including but not limited to food outlets, food production, recycling, waste handling, vehicle respraying, power plants, traffic emissions, and agriculture.

Odour assessments for planning are undertaken using the methodology outlined in Guidance on the Assessment of Odour for Planning (IAQM, 2014). The approach by IAQM uses predictive or observational methodologies to determine the level of adverse effects caused by odour.

During an Odour Assessment, multiple analytical assessments are utilised by consultants to determine the level of adverse effects caused by odour:

• Risk-based assessment using the source-pathway-receptor concept;
• Atmospheric dispersion modelling using complex software;
• On-site Sniff Tests; and
• Complaints analysis.

The level of odour impact is determined by the consultant following on-site survey and investigation, with reference to:

• Frequency of detection;
• Intensity as perceived;
• Duration of exposure;
• Offensiveness;
• and Receptor sensitivity.

Using analytical assessments and defined methodologies, odour assessments identify whether there is a risk of odour annoyance and provide mitigation where necessary to protect residents and businesses.

The United Kingdom commonly sees changes of use for commercial and residential properties above commercial spaces. When such changes involve use classes requiring commercial kitchens, there’s a potential for noise and odour impact. Environmental Health and Local Planning Officers actively use conditions to protect residents, following the guidance outlined in Defra’s 2005 document, “Control of Odour and Noise from Commercial Kitchen Exhaust Systems.” This procedure takes into account factors such as the kitchen’s size, location, and nature, as well as the extraction system’s location and operating parameters, all relative to the local area’s sensitivity, to assess the risk of odour impact.

An Odour Management Plan outlines how odour will be managed at a site and often forms part of the Environmental Management Plan (EMP).

An environmental permit may be required from the Environment Agency if you do an activity that could:

• pollute the air, water, or land;
• increase flood risk;
• adversely affect land drainage.

Odour Management Plans are often requested in combination with an environmental permit. An approved Odour Management Plan often forms part of the permitting process. H4 Odour Management (Environment Agency, 2011) provides guidance on how to comply with your permit if your process emits odour.

A technical report is produced following completion of the Odour Assessment. Recommendations and proposed amendments are made within the report to ensure the development complies with relevant standards and guidance. For planning the report is provided to the Local Authority (Council) for approval. The responsibility falls on the developer to ensure all recommendations, amendments and mitigation measures are completed.

Unsurprisingly the software utilised for Odour Impact Assessment is highly specialised. For atmospheric dispersion modelling which regularly forms part of the assessment, we utilise specialist modelling software.