When is odour sampling necessary or useful?

Written by Plistina Almeida and Simon Welchman


People don’t realise that odour is a very common environmental concern that is the subject of much research and environmental regulation. Whilst odours are not normally harmful to health, they can have a significant negative impact on a community.


Odour is inherent to some industries such as intensive cattle, poultry and pig farming, manufacturing, waste wastewater treatment and composting.


The level of annoyance or nuisance from a particular odorous activity can be described as a function of:

  • The intensity or strength of an odour
  • How often odours are detectable – for example, odour emissions may be continuous or intermittent, the strength of odour may be weather dependent or process dependent, emitted routinely as part of the normal process or occasionally due to process upsets
  • The duration of exposure to odours
  • The character and offensiveness of the odour – how the odour ‘smells’, i.e. how pleasant or unpleasant is the odour.


The location where odours are observed will also influence whether the odours cause nuisance.  For example, a person will generally be less tolerant of industrial odours that can be detected in their home compared with odours that are detected whilst driving passed an industrial facility.


There are a number of ways that odours may be emitted from commercial activities. For example:

  • Stacks and vents are commonly used in industrial processes to discharge odorous air vertically to aid in dispersion and reduce the potential impact at ground-level. Stacks and vents may follow odour control systems such as scrubbers or carbon filters. Some odour emissions from building facilities are odourous vapours arising from boiling activities, for example. Vapours from heating and boiling in kettles are discharged directly through vertical stacks into the atmosphere. Odour emissions are likely to be greatest during the boiling process as the most vapour is generated.
  • Fugitive emissions – Outdoor activities such as the ones in cattle and poultry farming, landfilling and composting face different challenges as most of the times, the availability of mitigation strategies is limited. In this case, design studies play a very important role as they define the location of sheds, ventilation requirements, etc.


Determining the odour sources and the appropriate mitigation strategies is the job of an odour expert. There are a several already established assessment methods within the odour guidelines and the odour literature. Requirements also vary according to the different State Government requirements, Planning Schemes, local environment plan, characterised zones or similar.


Odour assessments are commonly based either on a dispersion modelling study or a separation distance study (e.g. for intensive agricultural activities such as poultry farms, feedlots and piggeries). Both types of assessment rely to a greater or lesser extent on information about the activity, meteorology, terrain, land use and geographical location of sensitive receivers. The choice of dispersion model will depend on the circumstances and on the requirements of the regulator or planning authority.


How does an odour expert determine if odour sampling is necessary?

Odour sampling may be conducted because it is a requirement of an environmental license or approval.  It may also be conducted to inform an odour assessment that may be required as part of a development application for a new or expanded industry. Or even as part of an investigation of odour nuisance at a region.


In the context of an odour assessment study, the key considerations to determine the need for odour sampling are as follows:

  • What aspects or activities of the proposed development are likely to generate odour emissions?
  • Do odour generating activities currently operate at the subject site or elsewhere? Site specific sampling can be invaluable, particularly for activities that are unique or that involve odorous materials that are site or region specific.
  • Is there existing research that provides a robust and reliable basis to estimate emissions? This is particularly useful for greenfield sites.  Some industries have coordinated research into odour emissions that can provide a comprehensive and robust basis to estimate odour emissions.  Some of this research has been adopted in regulatory guidance or is recognised by regulators as the best practice approach.
  • Does the proposed activity operate or adopt management or control measures that are somewhat unique? For example, odour sampling can provide a transparent and robust basis to quantify the change in odour emissions that can be achieved by management measures or other emission controls.  Such benefits may not have previously been determined with any certainty.


However, in Air Quality and Odour studies, there is no “one-size-fits-all approach”. A good example of this is the investigation of odour nuisance in areas where several industries are likely to vent odorous air pollutants but the specific cause is illusive. In some cases, long-term meteorological observations and complaints analysis can play a critical role in deciphering the puzzle.


How can Katestone help you?

Katestone can help you determine the best methodology to assess odour impacts within a location. Our team is also experienced in advising when odour sampling will render data that is good enough to pinpoint odour-generating problems and whether mitigation strategies are applicable.


Our team is experienced in assessing odour emission from all types of agricultural and industrial activities including, composting, anaerobic digestion, landfill, industrial precincts, egg and meat poultry farms. We go the extra mile in planning the study to ensure that a technically robust and transparent odour assessment will be delivered to solve the client and the community’s problems.


Katestone’s experts have regularly been called to work as expert witness in legal proceedings for developments. Our team has made significant contributions to a large number of odour impact assessments that have resulted in approval of developments throughout Australia.


Contact us today for Clear Skies.


This article featured in the Katestone’s Clear Skies 2021 Winter edition. Click here to view other featured articles.


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