British Standards Relevant to Agriculture

British Standard Summaries

BS5502: Part 33: 1991
Building and Structures for Agriculture.
Guide to the Control of Odour Pollution.

The text herein is not a a full reproduction of the British Standard. It is summary based upon interpretation of the original text and not intended as a replacement for the full text. It should be used for general guidance only.

BS5502 is sub-divided into a number of individual standards. These can be broadly broken down as follows:

  • Part 0: Introduction
  • Parts 10 - 19: Reference information
  • Parts 20 - 39: General designs
  • Parts 40 - 59: Livestock buildings
  • Parts 60 - 79: Crop buildings
  • Parts 80 - 99: Ancillary buildings

This part of BS5502 identifies those operations which commonly occur in agriculture and horticulture buildings and structures which can give rise to unacceptable odours. It also provides guidance on mitigation measures.


  • The intensity and unacceptability of odours is subjective and related to the environment. Individuals may react differently to odours.
  • Unpleasant smells are not necessarily harmful but some are, for example hydrogen sulphide (very toxic) and ammonia can be generated  from livestock wastes.
  • Some toxic and otherwise harmful gases are not odourous and can build-up undetected e.g. carbon monoxide and carbon dioxide.
  • Methods for evaulating odours have been extensively researched. Standard measures do now exist.
  • The Environmental Protection Act 1990 protects against odour nuisance.
  • Odour reduction is mainly achieved by dilution with clean air.
  • The spread of odour from its source is influenced by local climate and topography.
  • Unacceptable odours can arise from:
  • Chemical additives and masking agents are not a substitute for good management practice or good building design.

Odour control

  • When planing new buildings or facilities consideration should be given to potential odour nuisance.
  • Planning regulations normally prevent livestock waste storage facilities to be located within 400m of a protected building - that is a building normally occupied by people which are not part of the agricultural holding.
  • Odour strength can be related to livestock numbers.
  • The production system and waste management system will also affect odours.
  • The accumulation of dung and slurry in channels and pits over time can significantly increase smells.
  • Livestock buildings in windy situations are at greater risk of producing an odour nuisance.
  • Livestock wastes can be pre-treated before land spreading to reduce odours. Such treatment processes include slurry aeration with oxygen and anaerobic digestion. Other options include treatment with chemicals or biological agents and applying the waste to land using techniques which reduce the release of odourous compounds such as injection.
  • Odours from stored waste can be dependant on the management system and storage method. Wastes can be treated with chemicals or biological agents to reduce odours. Odours can be contained or prevented by aeration / agitation of the waste.
  • Ensuring sufficient suitavble waste storage capacity is available will help reduce odour problems.
  • Odours from livestock buildings can be minimised by:
    • ensuring building discharge points are in positions where good atmospheric dispersion can be achieved.
    • odour retaining mediums are utilised.
    • unpleasant odour masking agents can be used.
  • Livestock building design should consider odour problems. The full Standard provides information on construction, flooring, ventilation and cleaning plus livestock husbandry and management.
  • Animal feeds can cause odour probelms from exhaust gases, dust, storage, spillage and swill.
  • Silage clamps are a common cause of odour nuisance.  Poorly made silage is more odourous than properly made silage.

A British Standard nor this summary does not, necessarily, include all the necessary information for correct implementation of the Standard to any specific application. This is purely the responsibility of the user. Standards are updated by either amendment or revision. Users should ensure that they are using the latest version.

The full text of this Standard can be obtained from the British Standard Institution

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