LÉGISLATION

Overview of relevant legislation with regard to control of odour releases and odour nuisance.

This information has been provided for guidance purposes only and Odournet accept no responsibility whatsoever for the accuracy or completeness of the information provided. Corrections, suggestions and contributions by visitors and for this section are welcome and should be sent to webmaster@odournet.com.

Australia
Belgium
Canada
Denmark
Germany
Japan
New Zealand
The Netherlands
 United Kingdom
United States
Other countries

Australia
In Australia the states have the responsibility for setting air quality policies for odour. The different states have traditionally taken very individual approaches. Recently there appears to be a trend towards convergence, as is shown in a number of recent draft policies, some of which are discussed below.
A main development supporting the shift from traditionally qualitative odour regulations to quantitative regulations is the development of an Australian standard for odour measurement, that has used the CEN draft EN13725 ‘Air quality – Determination of odour concentration by dynamic olfactometry’ as a starting point. The new Australian Standards document has been developed jointly with New Zealand and is titled:
• draft Australian standard DR 99306 Air quality - Determination of odour concentration by dynamic olfactometry.
Most Australian states are expected to adopt this standard, with the exception of Victoria, that so far indicates continued use of its own olfactometry method.
The differences between the standards have been estimated in the recent NSW-EPA draft odour policy (see section 0):
Four different dynamic olfactometry methods were considered, as follows:
• V EPA method B2, used in Victoria
• QDEH method 6, Queensland
• NSW EPA/SWB method
Table 12 Values of constant k for four regulatory compounds to calculate maximum concentration allowed in liquid effluent, Japan.
• Draft Australian or European CEN standard methods.
To convert odour units from one standard method to another, the following simplifying assumptions were made by the New South Wales EPA:
1 OU V EPA Method B2 = 0.5 x ou_E/m³
(Bardsley and Demetriou 1999)
1 OU QDEH Method 6 = 3.5 x ou_E/m³
(Verral 1997)
1 OU NSW EPA/SWB Method = 3 x ou_E/m³
(NSW EPA and SWB 1994)
It must be noted that these factors are gross simplifications and may be significantly affected by random variability in the methods, that may be large relative to the methodological bias of each method.
Using these factors a degree of comparison can be made of historical and proposed odour exposure criteria in Australia. From this comparison it becomes clear that considerable differences exist between the criteria as proposed in the different states of Australia.

Australia – Western Australia
The Environmental Protection Authority of Western Australia has issued draft guidance on odours in April 2000:
• Environmental Protection Agency, Guidance for the assessment of environmental factors (in accordance with the Environmental Protection Act 1986). Assessment of Odour Impacts, No 47, Draft, April 2000.
The guidance is based on the environmental Protection Act of 1986, which states:
• Section 49(1) In this section unreasonable emission means an emission of noise, odour or electromagnetic radiation which unreasonably interferes with the health, welfare, convenience, comfort or amenity of any person.
• Section 49(5) A person who:
a. emits and unreasonable emission from any premises or
b. causes and unreasonable emission to be emitted from any premises commits an offence.
The Guidance assumes that best practicable engineering design and best practice management
will be applied with a view to minimise odour impacts. For odour impact assessment it takes an approach based on olfactometry to determine emissions at source, combined with dispersion modelling. Air quality criteria are formulated on that basis. The criteria are differentiated for different odorants or odorant mixtures on the basis of the relation between perceived intensity and odour concentration.
An odour assessment comprises three main steps:
• Odour source quantification and intensity analysis through dynamic olfactometry;
• Dispersion modelling of the odour emissions; and
• Comparison to appropriate criteria.
For olfactometry, the standard refers to the Dutch NVN2820 standard, the CEN draft EN13725 and the draft Australian standard DR 99306 Air quality - Determination of odour concentration by dynamic olfactometry. For intensity analysis the German standard method VDI3882.
Dispersion modelling is to be carried out using the AUSPLUME model.
The general odour impact criterion is:
• Odour impacts will not exceed 2 odour units (based on the NVN2820 standard) with one hour averaging and 99.9 percentile compliance.
It is not clear whether the authors of the guidance are aware that 2 ou/m3 according to NVN2820 is actually equivalent to 1 ou_E/m^-3.
The applicant can also choose to propose an alternative criterion, where an ‘equivalent odour concentration’ is determined to replace the default odour impact criterion of C99.9, 1-hour < 1 ou_E/m^-3 To arrive at such a criterion, the intensity curve needs to be determined according to the VDI3882 method. The odour concentration that is equivalent with the ‘distinct odour’ intensity scale step will be used to replace the default C99.9, 1-hour concentration.
An example is provided for poultry rearing odours, that are ‘distinct’ on the intensity scale at a concentration of 7 ou/m3. This would result in an odour guideline criterion for air quality of C99.9, 1-hour < 7 ou/m3.

Australia – New South Wales
The Environmental Protection Agency of New South Wales issued a draft policy on odours in January 2000:
• NSW EPA, Assessment and Management of Odour from Stationary Sources In NSW, Draft, Sydney, January 2001.
This policy is accompanied by a separate booklet:
• NSW EPA, Technical Notes: Assessment and Management of Odour from Stationary Sources in NSW, Draft, Sydney, January 2001.
The documents are available on the website of the NSW-EPA: www.epa.nsw.gov.au.
The legal basis for the policy is the Protection of the Environment Operations Act 1997 (POEO Act) and the Environmental Planning and Assessment Act 1979 (as amended).
The POEO Act defines ‘air impurities’ and ‘air pollution’ as follows:
air impurity includes smoke, dust (including fly ash), cinders, solid particles of any kind, gases, fumes, mists, odours and radioactive substances.
air pollution means the emission into the air of any air impurity.
Section 129 of the POEO Act prohibits the emission of an ‘offensive odour’ from scheduled premises. However, it also provides [in 129(2)(a)] for negotiation of acceptable odour limits through the licensing process. The provision is as follows:
129. Emission of odours from premises licensed for scheduled activities
(1) The occupier of any premises at which scheduled activities are carried on under the authority conferred by a licence must not cause or permit the emission of any offensive odour from the premises to which the licence applies.
(2) It is a defense in proceedings against a person for an offence against this section if the person establishes that:
(a) the emission is identified in the relevant environment protection license as a potentially offensive odour and the odour was emitted in accordance with the conditions of the licence directed at minimising the odour, or
(b) the only persons affected by the odour were persons engaged in the management or operation of the premises.
(3) A person who contravenes this section is guilty of an offence.
The draft policy is meant to provide an operational meaning to the concept of ‘offensive odour’.
The stated aim of the policy is:
‘…to provide an effective future planning and regulatory regime for potential odourgenerating activities. The goal is to introduce a system that will protect the environment and at the same time promote fair and equitable outcomes for odour generators and people affected by odour emissions.’
The policy states a general set of odour impact criteria:
1 Ground level concentration (glc) criteria for individual odorous pollutants.
The policy adopts the Victoria EPA ground level concentration criteria. These criteria are based on odour threshold or toxicity threshold (whichever is more stringent) and should not be exceeded at any location beyond the boundary of a facility.
2. Odour performance criteria for complex mixtures of odours.
The policy introduces a range of odour criteria which depend upon the surrounding population density. These criteria should not be exceeded at the nearest sensitive receptor (both existing and any likely future sensitive receptors). If a receptor is, or is likely to be, located near the boundary of a facility, then the criteria should be applied at and beyond the boundary of the premises. A level of 7 odour units (OU/m3) is deemed to be the appropriate exposure level for a single affected residence. For a larger population, in which there will be a greater range of sensitivities to odour (and a higher number of more sensitive individuals), acceptable odour is defined to be 2 OU/m3.
Depending on the specific nature of the odour involved, these criteria may be applicable to point sources or diffuse sources or a combination of both.
In no situation will the glc or odour performance criteria be used as environment protection licence conditions. Compliance with these criteria is difficult to measure so they are meaningless as licence conditions. For point sources, a specific stack emission concentration limit may be calculated so that the glc or odour performance criteria can be met. Such stack emission concentration limits may be used as licence conditions where appropriate.
The policy motivates the exposure criteria as follows:
Experience gained through odour assessments for proposed and existing facilities in NSW indicates that an odour performance criterion of 7 OU/m3 is likely to represent the level below which ‘offensive’ odours should not occur (for an individual with a ‘standard sensitivity’ (to odours). Therefore, the policy recommends that, as a design criteria, no individual be exposed to ambient odour levels of greater than 7 OU/m3. Appropriate averaging periods are discussed in Technical Note 3.
Odour performance criteria need to be designed to take into account the range in sensitivities to odours within the community, and provide additional protection for individuals with a heightened response to odours, using a statistical approach which depends upon the size of the affected population. As the affected population size increases, the number of sensitive individuals is also likely to increase, which suggests that more stringent criteria are necessary in these situations. In addition, the potential for cumulative odour impacts in relatively sparsely populated areas can be more easily defined and assessed than in highly populated urban areas. It is often not possible or practical to determine and assess the cumulative odour impacts of all odour sources that may impact on a receptor in an urban environment. Therefore, the proposed odour performance criteria allow for population density, cumulative impacts, anticipated odour levels during adverse meteorological conditions and community expectations of amenity.
Where a number of the factors above simultaneously contribute to making an odour ‘offensive’, an odour criteria of 2 OU/m3 at the nearest sensitive receptor (existing or any likely future receptor) is appropriate, which generally occurs for affected populations equal to or above 2000 people.

The policy identifies three levels of impact assessment:
- Level 1 is a ‘rule of thumb’ assessment based on generic parameters for the type of proposed facility and site. It requires minimal data and uses simple equations to conservatively predict the extent of any odour impact.
- Level 2 is a ‘screening’ level dispersion modelling technique, using worst case input data (rather than site-specific data). It is more rigorous, less conservative and more realistic than a Level 1 assessment.
- Level 3 is a ‘refined’ level dispersion modelling technique using site-specific input data. This is the most comprehensive and most realistic level of assessment available.
The proponent of a proposed facility should choose the level of assessment (to be presented in a development application or environmental impact statement) depending on the specific characteristics of the proposal and the likelihood of operational odour impacts.
The policy sets out a very ambitious target in terms of dispersion modeling, based on the 99.9 or 100th percentile of 3-minute average concentrations. These are to be calculated using a sophisticated peak to mean ratio mechanism that was developed specifically for this policy.
The relationship between the levels of assessment and the criteria to be applied is outlined below:
To quantitatively determine the frequency, intensity and duration of odours, the groundlevel concentration criteria should be reported as the 100th percentile of dispersion model predictions for Level 2 odour impact assessments and the 99.9th percentile for Level 3 odour impact assessments. For point source discharges, stack-emission concentration limits can be included on the environment protection licence. This will help to ensure compliance with the ground-level concentration criteria.
For dispersion modelling purposes, the glc criteria should be applied at any location at or beyond the site boundary as follows:
1. Impacts for glc pollutants must be reported for an averaging period of 3 minutes.
2. For Level 2 odour impact assessments, impacts must be reported as the 100th percentile of dispersion model predictions.
3. For Level 3 odour impact assessments, impacts must be reported as the 99.9th percentile of dispersion model predictions.
4. Compliance with the glc criteria is to be determined by using source emission measurements and dispersion modelling only.
5. For point sources, dispersion modelling results will be used as the basis for developing licence limit concentrations on stack discharges for glc pollutants.
6. It is not appropriate to use the glc criteria as default license conditions for a facility.
The policy offers the option to develop specific odour exposure criteria through the process. To download the complete version of this text including graphics click here.

Australia - Victoria
Since the Victoria EPA was formed in 1970 it has developed an approach for reducing and managing odours. Odours and aesthetics are specifically included in the Environment Protection Act of 1970, which in section 41 prohibits ‘making the atmosphere offensive to the senses of human beings’. EPA licences for premises scheduled under the Environment Protection (Scheduled Premises and Exemptions) Regulations of 1996 include the standard condition that ‘odours offensive to the senses of human beings must not be discharged beyond the boundaries of the premises’.
Odour prevention and control has been formalised in State Environment Protection Policies (SEPP’s) of which two relate to air issues:
• SEPP AAQ : Ambient Air Quality
• SEPP AQM : Air Quality Management
The essence of the approach is :
• The exposure to a long list of substances is to be limxited by setting limits for ground level concentrations (GLC’s). A number of these glc’s are set on the grounds of odour, while others are defined on the basis of toxicological data.
• For odours that are not included in the GLC substance list, a limit concentration of 1 OU is set
• For assessment of GLC’s dispersion modelling may be used, with a prescribed Gaussian model, calculating a 99.9-percentile for 3-minute average concentrations.
• A prescribed Victoria method of olfactometry is to be used, called the EPA B2 method. Victoria is the only Australian state that intends to maintain its own standard protocol for olfactometry, instead of adopting the impending Standards Australia method.
The policy is currently being revised. The main change is that the list of GLC concentrations would be replaced by values indicated in a document of the US-EPA:
• US-EPA, (1992) Reference Guide to Odor Thresholds for Hazardous Air Pollutants Listed in the Clean Air Act Amendments of 1990, US Environmental Protection Agency, (EPA600/R-92/047).
An overview of the current policy objectives and the proposed changes in the drafts is provided in the background paper produced by the Victoria EPA, printed below:
APPROACHES TO ODOUR MANAGEMENT
INTRODUCTION
Offensive odours from industry are a worldwide problem that has existed for many years. Since its inception in 1970, EPA Victoria (EPA) has developed a consistent approach for reducing and managing odours in the local environment. Significant improvements have been made since that time, however odour continues to be a problem and about 40% of all the pollution complaints currently received by EPA are about odour. Odours and aesthetics are specifically included in the definition of ‘environment’ in section 4 of the Environment Protection Act 1970 (the ‘Act’).
Pollution of the atmosphere is an offence under the Act and, as defined in section 41, prohibits the act of making the atmosphere ‘offensive to the senses of human beings’.
The Beneficial Uses specified in the SEPP (AQM) include the protection of local amenity and aesthetic enjoyment. EPA has developed a range of statutory and nonstatutory procedures for preventing and resolving odour problems, including works approval and licensing, pollution abatement notices, and the development of environment improvement plans. EPA licences for premises scheduled under the
Environment Protection (Scheduled Premises and Exemptions) Regulations 1996 include the standard condition that ‘odours offensive to the senses of human beings must not be discharged beyond the boundaries of the premises’. Odour prevention and control strategies have been formalised in State environment protection policies (SEPPs). Currently there are two SEPPs relating to air issues, State Environment Protection Policy (Ambient Air Quality) [SEPP (AAQ)] and State Environment Protection Policy (Air Quality Management) [SEPP (AQM)]. EPA is currently
varying the SEPP (AQM). SEPP (AQM) refers to odours in two ways:
1. Odours from emissions of one or more known chemicals; each substance having its own odour strength and characteristics.
2. Odours from emissions of a mixture of unidentified substances, for example, odours from piggeries and broiler farms.
For known compounds, the odour strength of the emissions can be reliably estimated by measuring the concentration of the chemical. For mixtures of unknown substances, odour strengths are estimated by a panel of trained human noses using the EPA’s standard analytical procedure, No. B2 Odour Dynamic Olfactometry, known as the B2 method. Odour strengths are calibrated based on the principle that 1 odour unit (OU) is the level of odour which can just be detected by the average human nose.
CURRENT POLICY OBJECTIVES
Clause 42 of the existing SEPP (AQM), requires the control of odorous substances that ‘create or are likely to create objectionable conditions for the public’. Odour management requirements in the existing SEPP (AQM) include:
• at least good control practice for all emission sources;
• additional technological, operational and management requirements for particular industries or activities listed in Schedule F to the policy;
• appropriate land use planning to include buffer distances to limit the impact of odours. The EPA document, Recommended Buffer Distances for Industrial Residual Air Emission (EPA Publication AQ 2/86 July 1990), provides the currently recognised recommendations in Victoria.
• design ground level concentrations for odorous pollutants, where the odour thresholds are more stringent than the health-based criterion for the same substance.
• a design ground level concentration for all other odorous wastes of 1 OU;
• plume calculation procedures for modelling emissions using a 3 minute average, to ensure that proposed emissions will meet the appropriate design ground level concentration; and
• odour measurement using the EPA’s standard B2 method.
DRAFT POLICY OBJECTIVES
The overall approach to emissions management in the draft SEPP (AQM) is based on the principles of eco-efficiency and the waste hierarchy. In particular, the management of emissions will focus primarily on emissions avoidance and minimisation through the application of cleaner production principles. Residual emissions will then be appropriately controlled and dispersed to protect the beneficial uses of the environment.
Issues specifically related to odour management
Incorporated in the draft SEPP (AQM) and detailed in the relevant guidelines for environmental management (GEMs) include:
• the selection and use of design criteria for odour;
• methods for odour modelling and odour measurement;
• the role of separation distances (buffer distances) and land use planning; and
• additional control requirements for particular groups of industries.
The odour-based dglcs in the existing SEPP (AQM) were derived from a review of the published odour thresholds available at the time of the development of the SEPP (The Air Environment) with a safety factor applied. The general approach was to adopt the lowest published value to provide protection for the most sensitive members of the population. These dglcs were used in the same manner as the toxicity-based dglcs – as a modelling tool used with the regulatory model in the assessment of the design of industrial premises. In the review of the SEPP (AQM) it was considered that the odour-based design criteria must be updated to reflect the currently accepted odour thresholds for the pollutants covered by the policy. The draft SEPP (AQM) proposes to adopt the US EPA odour thresholds for single chemical odours. EPA decided that the odour thresholds published by the US EPA provided the most appropriate list of published odour thresholds for the purposes of the policy. This approach is also consistent with the approach taken by other jurisdictions in Australia. This isdiscussed further in the background paper, Indicators for Air Quality Management and Criteria for Assessment. General odours will be formally defined in the GEM for
Indicators for Air Quality Management, as (unclassified) air quality indicators of local amenity and aesthetic enjoyment of the air environment. For these indicators, a design criterion of 1 OU at the boundary of the premises will be retained for design purposes to protect amenity in all areas. Prior to EPA issuing a works approval for new sources of emissions, estimates of the resulting maximum ground level concentrations (99.9 percentile value) of pollutants need to be calculated to ensure
compliance with design criteria. The draft SEPP (AQM) requires that the EPAapproved dispersion model be used for these calculations. Key features of the application of dispersion modelling procedures to odorous substances are:
• modelling is performed to predict maximum (99.9 percentile), ‘worst case’, ground level concentrations of indicators, using a full year of relevant meteorological data;
• for odorous emissions, 3 minute average figures at ground level are calculated for comparison with design criteria; and
• the predicted ground level maxima in the local air environment must be less than the design criteria. Detailed information on the use of the approved model will be available in the GEM for Dispersion Modelling.
A background paper on modelling issues has been released for consultation.
Measurement
Odours arising from known chemicals with design criteria can be individually measured using standard laboratory techniques. The EPA B2 method for odour measurement is used for odours comprising a mixture of one or more substances that have not been individually identified. The current method has been used satisfactorily by EPA for a number of years to assist in the resolution of odour problems. An enhanced B2 method is currently being developed to ensure the best possible results are obtained.
SEPARATION DISTANCES
Proper land use planning is one of the most important tools in odour management.
Many odour problems can be avoided by the appropriate siting of new facilities.
Separation distances are provided as a risk management tool to manage unexpected or accidental emissions from an industry. Separation distances provide an additional level of protection by allowing more distance and space in which emissions may dissipate without adversely affecting sensitive land uses. Separation distances are not a substitute for good odour management as described in section 3.1. They are provided to cater for non-routine emissions that may arise from upsets in normal
operations of a premise. The draft SEPP (AQM) will include a GEM for recommended separation distances between emission sources and sensitive land uses. Planning and other responsible authorities will be required to apply the guidelines in assessing the suitability of proposed development locations and the potential impacts of development. Separation distances will not be offered or used as a substitute for the effective management of emissions at source.
RESOLUTION OF ODOUR PROBLEMS
Complaints about odour remain the primary indicator of the acceptability of odours in particular situations and a key driver of improvement programs for particular premises that are causing odour
problems. As a general rule EPA will seek to negotiate agreement on the measures necessary to resolve odour problems in consultation with the affected community and the management of the responsible premises. Should remedies not be developed and implemented to EPA’s satisfaction, then EPA will employ statutory tools requiring action to be taken to reduce odour emissions. Any enforcement action taken will be in accordance with EPA’s enforcement policy.
Copies of the draft policies, draft PIA and accompanying background papers can be downloaded from EPA’s website www.epa.vic.gov.au

A.7.4. Australia - Queensland
The main focus in Queensland for odours is on cattle feedlots and other sectors of primary production.
A schedule of setback distances has been developed for cattle feedlots, in a document titled:
The Queensland Government Guidelines for Establishment and Operation of Cattle Feedlots, 1989. It uses a formula with a number of inputs: number of cattle, stocking density, density of population in the vicinity, terrain factor and vegetation factor.
Recently an air quality criterion of C98, 1-hour = 10 ou·m-3 was used as a condition in a licence for a new piggery in Queensland.

Belgium
Currently a policy review is under way to establish a concerted policy on odours in Flanders, the Northern part of Belgium. The Flemish Environmental Policy Plan 2002-2006 contains an initiative to define odour exposure standards for 16 sectors of economic activity.
This will be done using a methodology recently used to in a long term research programme looking at dose effect relations, focussing on five pilot sectors of economic activity:
• Pig farms
• Slaughterhouses
• Paint application
• Wastewater treatment plants
• Textile plants
The techniques rely on field panels that determine the maximum distance at which the source can be detected. This distance and the weather conditions during the field test are then used as input in a Gaussian dispersion model to estimate the emission of the source in ‘sniffing units’.
The concept of ‘sniffing unit’ is similar in use to odour units, but measured in the field rather than in the laboratory, using stack samples, as is done for odour units. (Van Broeck e.a., 2001)
The calculated emission in sniffing units is then used in dispersion modelling to determine percentiles of 1 hourly calculated odour concentrations in sniffing units.
Intermediate results have been reported recently in:
• Van Broeck, G., Van Langenhove, H, Nieuwejaers, B., (2001) Recent odour regulation developments in Flanders: Ambient odour quality standards based on doseresponse relationships, In: Proceedings of the 1st IWA International Conference on Odour and VOC’s: Measurement, Regulation and Control Techniques, University of New South Wales, Sydney, March 25-28, 2001, ed. J. Jiang, International Water Association, ISBN 0 7 334 1769 8.
In this report, the authors reported finding significant correlations between odour exposure and surveyed annoyance in all of the 16 study locations. The background percentage of annoyance varied between 0% and 15%. For three sectors a ‘no effect level’ was established:
• Slaughterhouses: 0.5 sniffing units as a 98th percentile of hourly calculated odour concentration
• Paint spraying facilities: 2.0 sniffing units as a 98th percentile of hourly calculated odour concentration
• Wastewater treatment plants: 0.5 sniffing units as a 98th percentile of hourly calculated odour concentration.
For pig production units and textile plants no unambiguous ‘no effect level’ was reported.

Canada
In Canada the responsibility for odour regulations lies with the provinces. Various provinces have their own odour regulation or policy, typically aimed at agricultural sources.
Ontario has a regulation since 1976 titled Agricultural Code of Practice that applies setback distances to livestock facilities. As an example:
• for 1000 fattening pigs a setback distance would apply of 405 m to a home and 810 m to a home not belonging to the farm or an urban area.
• for 52 000 chickens a setback distance would apply of 234 m to a home and 468 m to a home not belonging to the farm or an urban area.
Manitoba also uses a schedule of setback distances for livestock units.
In Alberta an ambient air quality guideline for Hydrogen Sulphide of 10 ppb/v as a one hour average is applied for the specific purpose of odour impact management. This would amount to 20 ou_E/m^-3 on the basis of the smell of H2S only, with an odour threshold of 0.5 ppb/v. In addition an Ammonia criterion of 2 ppm/v applies. On 10 days in 1998 and 1999 the Alberta Environment agency conducted downwind surveys of 14 livestock feeding facilities. They found that the air quality criterion for Hydrogen Sulphide was exceeded at two of these sites at 30 m from the source. For Ammonia all measurements were within the guideline criterion.

Denmark
In Denmark an exposure criterion is used which stated that the ground level concentration should not exceed 5 to 10 ou·m-3 , depending on the location (residential or non-residential), at a 99-percentile, with an averaging time of 1 minute.

Germany
The law concerning air quality issues in Germany is the Bundesimmissionsschutz Gesetz (known as ‘BimSchG’), or the Federal Immission Control act of 1990, which is available in English from the Ministry for Environment, Nature Conservation and Nuclear Safety.
All odours from any commercial installation are considered an annoyance, according to §3 of BimSchG’. For licensing and enforcement, however, the issue is to determine whether the annoyance constitutes a ‘significant disturbance’, on the basis of the ‘relevance of the annoyance’. However, the ‘BimSchG’ does not provide for criteria to determine when an annoyance becomes a significant disturbance (nuisance).
The second relevant official regulatory document, aimed at providing technical guidance for specific industries on how to achieve the general principles concerning air quality in the ‘BimSchG’ also fails to provide operational annoyance criteria. The Technische Anleitung zur Reinhaltung der Luft, or TA-Luft, details the technical measures, expected to be applied in different sectors of industry and agriculture, including methods for assessment. The TA-Luft is available in English:
• Technical Instruction on Air Quality control (Erste Allgemeine Verwaltungsvorschrift zum Bundesimmissionsschutzgesetz), Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, Bonn, 1986 (GBBl. P.95)
The TA-Luft defines a maximum ‘odour frequency’, as an ambient air quality characteristic, but does not specify a method to assess this parameter. In 1994 the Department of the Environment of Nordrheinland Westfalen introduced a method for this purpose, aimed at assessing ambient air quality for odours in the vicinity of an existing source. The document is available in English translation:
• Determination and Evaluation of odour immissions – Odour exposure guideline (Feststellung und Beurteilung von Geruchsimissionen – Geruchsimmissionsrichtlinie), Länderausschuß für Imissionsschutz, LAI-Schriftenreihe o. 5, Berlin 1994.
This method prescribes a method for long-term field panel observations, in which the fraction of ‘odour hours’ is determined by a team of assessors on pre-defined locations on a grid around the source in question. The method has been described in a standard:
• VDI3940, (1993) Determination of Odorants in Ambient Air by Field Inspections, Beuth Verlag, Düsseldorf, Germany.
This method can be applied to determine licensing applications (Both, 2001).
The exposure criteria are differentiated for areas with different land use:
• < 10% ‘odour hours’ in residential areas
• < 15% ‘odour hours’ in industrial areas
However, in most cases, a technical guideline is applied, that provides detailed advice on the design and operation of the activity of the applicant. An example of such a guideline is:
• VDI3475 Part 1 Emission reduction for biological waste treatment units - Collection and Composting for units with a capacity = 0.75 Mg/h. (in German), Beuth Verlag, Düsseldorf, Germany.
Agricultural odour regulation in Germany
For agricultural odours, standards exist describing standard practice and the techniques that are to be applied to limit environmental impact, including odour emissions. These documents are:
• VDI3471:1986 Emission Control.
Livestock management – Pigs
• VDI3471:1986 Emission Control.
Livestock management – Hens
• VDI3473:1994 Part 1 (draft) Emission
Control. Livestock farming – Cattle.Odorants.
In addition to technical guidance on the design and operation of pig units, the technical standard, VDI3471:1986, contains a graph providing setback distances, for pig units of different sizes. In determining setback distances, operational methods and design of the pig unit are taken into account, using a system of assigning points. A correction on the standard setback distance can be applied on the basis of the total number of points.
If a pig unit complies with the VDI3471 standard, and is located so that the setback distances are respected, that is in most cases sufficient ground for the local authority to grant a licence. In those cases where the distance to residences is less than 100m, or in cases where the setback distances cannot be attained fully, expert advice is sought to determine the application, using detailed assessments, typically based on atmospheric dispersion modelling.
The distance graph in VDI3471
The capacity of a pig unit is expressed in ‘Grossvieheinheiten’ (GV), that are equivalent to 500 kg live weight.
Once the number of GV units has been determined, a point system is applied to take design and operational practice into account.

Japan
Japan has a long track record in regulating odours. In the 1970’s around 20,000 complaints were registered each year. This number has been decreasing from year to year after the introduction of regulations in 1971, but has recently showed a significant increase, caused by increasing complaints against waste burning practices. (OSAKO, Masahiro, Dept. of Waste Management Research, National Institute for Environmental Studies, Japan.).
• Offensive Odour Control Law, Law No. 91 of 1971, amended by Law No. 71 1 June of 1995.
This Law was updated several times, in 1995 and in 1997. The Law applies to designated areas, where emissions are to be regulated. Governors of prefectures determine these areas, after hearing the local (municipal) authorities. Just over half of all municipalities in Japan have designated odour control areas.
The Law as it stands now identifies 22 individual odorous compounds and sets ambient limit values for each of these compounds.
The Japanese regulation is based on a specific method of olfactometry, based on triangle testing after preparing different dilutions of odour in small disposable sample bags by an injection method. The smells are assessed by selected panel members using a face mask and sniffing directly from the bag through a relatively large diameter glass connector tube. The panel members are selected based on a screening test using 5 chemical compounds, that are assessed in different concentrations using dipsticks and solutions of the odorants in paraffin or propylene glycol. The five selection odorants are: â-phenylethyl alcohol, methyl cyclopentenolone, iso-valeric acid, ã-undecalactone, skatole.
The standard protocol for the Triangle Olfactory Malodour Determination method is accepted as the method of preference for evaluating malodours by 40 of the 47 prefectures of Japan, and has been officially described in Notification No. 238 of the Tokyo Metropolitan Area, March 1977.
The Japanese triangle method for olfactometry yields a result for n-butanol of 38 ppb/v, which is compatible with the accepted reference value for the European odour unit of 40 ppb/v. The Japanese Offensive Odour Control Law expresses odour intensity as the Odour Index, which is:
Odour Index = 10 log(Odour Unit)
This is identical in concept and value to the dBod. The standard is based on the premise that an Odour Index associated with an odour intensity scale value of 2.5-3.5 is deemed acceptable.
The intensity scale used is:
• 0 - Not perceptible
• 1 - Faint smell (detectable)
• 2 - Weakly quality perceptible (recognition)
• 3 - Easily quality perceptible
• 4 – strong
• 5 – very strong
The Offensive Odour Control Law sets three
types of limit values:
• 1st criterion: Maximum concentration at site boundary, maximum ground level concentration or maximum concentration at 1.5 m above liquid surface of wastewater. For this criterion the criteria
for ‘acceptable’ concentrations are set according to fixed values. The actual value is to be determined by the prefectural governor (regional authority).
• 2nd criterion: Maximum concentration in a stack emission. This is calculated using simplified dispersion modelling equations, for different types of stacks (heights). The calculation essentially
serves to calculate the stack concentration corresponding to the acceptable (maximum) concentration at ground level, as defined in the previous 1st criterion at the site boundary.
• 3rd criterion: for odorous wastewater, based on the dissolved odorant concentration for four sulphur compounds. It uses a simple formula:
CLm = k x Cm
Where
CLm is the regulation standard limit of the odorous substance in a wastewater effluent in mg/l
k is a constant from Table 12, depending on compound and the flow of effluent
Cm is the criterion concentration for that compound in air, as determined by the appropriate authority.
In addition to a National regulation, regional authorities have issued their own regulations.
The Tokyo metropolitan area, with approximately 12 million inhabitants, has its own regulation, in force since 1977, setting limits for odour concentration in stack emissions (odour concentration 300, 500 or 1000 in the stack emission, depending on the land use) and for ambient concentration at the site boundary of 10, 15 and 20. These values appear to be equivalent to ou_E/m^-3, based on a comparison of the odour threshold for n-butanol.

New Zealand
New Zealand’s Resource Management Act 1991 imposes a duty upon industry to avoid causing “objectionable” or “offensive” odours to such an extent that they are likely to have adverse environmental effects.
Since 1995 New Zealand has a guideline for managing odour to make this general legal requirement operational: the Odour Management under the Resource Management Act (1995)
Most regional authorities however propose guidelines in more general common law terms: No objectionable odour at or beyond the property (site) boundary.
Most Regional Air Plans do not currently recommend a specific odour modelling guideline.
and prefer to put narrative rules in their Plans, including the following typical statement regarding selection of odour modelling guideline:
“Activities will be assessed having regard to the following matters: ... Whether the activity complies with the relevant national regulations, standards and codes of practice”(Source: Revised Proposed Regional Air Quality Plan for Northland, 16 May 1998).
At the time of writing this report, the only examples of full or partial odour modelling guidelines mentioned in Regional Air Plans in New Zealand are found in the Waikato and Otago Regional Council, summarised below.
Otago
Schedule 1.7 of the Proposed Regional Air Plan (February 1998) describes dispersion modelling procedures, and recommends using the 99.5 percentile of real meteorological data for assessment of effects. However, the Schedule does not recommend a concentration component to the odour modeling guideline, instead advising the applicant to consult the Regional Council to determine an appropriate guideline.
Waikato
Section 6.4.1.2 of the Proposed Waikato Regional Plan (September 1998) contains a section on modelling guidelines for determining “acceptable” odour for resource consent applications. The Plan takes care to emphasise that this is not a modelling guideline and should not be used or quoted as such; rather, it is a guide in assessing resource consent applications. Further, the guideline is applicable primarily to assessing new activities, but may also apply to existing activities as appropriate. The guideline is:
“One hour average concentrations of odour, as predicted by an ISC-type atmospheric dispersion model, should not exceed 5 OU/m 3 divided by the appropriate peak to mean ratio for more than 0.1% of the time. Odour emission concentrations (and rates) used in the ISCtype model shall be based on certainty-based forced-choice olfactometry.”
The recommended P/M ratios are derived from the New South Wales (Australia) draft guideline (2001). In the event that a full meteorological data set is not available, and screening data is used instead, then the guideline is still applied but to 100% of the model predictions.
In spite of the relatively vague approach by the regional authorities, air quality criteria in the form of odour exposure limits are used in some cases:
• A C99, 1-hour = 2 ou·m-3 as a 1-hour average was applied by the Auckland Regional Council to the Mangere Sewage Treatment Plant, Manukau City
• Southland Regional Council requires a maximum 3-minute odour concentration beyond the site boundary of 0.3 ou/m3. The Canterbury Regional Council has also used similar guidelines when assessing air consent applications.
In a recent report, commissioned by Auckland Regional Council and co-funded by the Ministry of the Environment of New Zealand, quantitative air quality criteria are suggested, of 5 to 10 ou_E/m^-3 at percentile values of 99.5 to 99.9. The full report is available on the Ministry website http://www.mfe.govt.nz and is titled:
• Freeman, T., Needham, C. Schulz, T., (2000) Analysis of Options for Odour Evaluation for Industrial or Trade Processes. CH2M-Beca for Auckland Regional Council.
The Ministry of the Environment has started a review of the guide to Odour Management under the Resource Management Act (1995). The review will assess how the guide has been applied, examine the current problems facing odour management in New Zealand and recommend updated guidance for a new guide to odour management.
Matters that are likely to be covered in the revised document are:
• recent case law and best practice toward odour management
• specific criteria for assessing atmospheric dispersion modelling for odour
• the relationship between odour management and land use
• the role of performance standards for odour
• methods for surveying community response
• standard methods for sampling and measurement of odour.
Draft reports are expected to be completed and available for comment by mid 2001.

The Netherlands
The basis of the Dutch policy on industrial odours is the First National Plan for the Environment or NMP-1 (VROM, 1988) in which specific targets are set:
• VROM, (1988) Nationaal Milieubeleidsplan I (NMP 1, English: National Environment Plan), Ministry of Public Housing, Planning and the Environment, The Hague, The Netherlands.
The target for objectives A75 and S37 in the NMP-1 was to reduce the number of residential dwellings ‘affected by odour exposure’ to less than 750 000 by the year 2000. This target was based on an assessment of what could be achieved by applying odour control ‘at source’. In the review of NMP-1, the National Survey of the Environment (Langeweg, 1998), this target was translated into reducing the number of residents affected by odour annoyance to ‘12% of the population’, which implies that a degree of impact to 12% of the population or less was deemed acceptable.
These general policy targets have been used as the basis for a succession of operational regulations and guidelines. As early as 1984, a guideline was published by the Ministry VROM that set stringent air quality targets for odour, based on limits for exposure calculated as a percentile of 1-hourly concentrations, using a national regulatory dispersion model (the LTFD model):
• VROM, (1984) Lucht indicatief meerjaren progamma lucht 1985-1989 (English: Indicative Long-Term Programme for Air Quality 1985-1989), Ministry VROM, The Hague, Netherlands, ISBN 90 12 04764 1.
The input for the model was to be provided by source emission measurements, using olfactometry. Air quality criteria were defined, as a limit for the 1-hour average odour concentration that could not be exceeded more than a defined percentage of annual hours.
This is the x ou_E/m^-3 as a y% percentile for hourly averages criterion. The following limits were proposed and later implemented in hundreds of license applications:
• C99.5, 1-hour < 0.5 ou_E/m^-3 for applications for new installations (sources), not to be exceeded at the nearest ‘odour sensitive location’ (e.g. residential property, schools, hospitals, recreational housing etc.)
• C98, 1-hour < 0.5 ou_E/m^-3 for applications for existing installations (sources) or expansion of such installations, not to be exceeded at the nearest ‘odour sensitive location’ (e.g. residential property, schools, hospitals, recreational housing etc.)
• C95, 1-hour < 0.5 ou_E/m^-3 for isolated residential houses located on industrial estates
• C99.9, 1-hour < 0.5 ou_E/m^-3 for discontinuous, incidental sources, not to be exceeded at the nearest ‘odour sensitive location’ (e.g. residential property, schools, hospitals, recreational housing etc.) Examples of such sources are loading/unloading operations, cleaning and opening of reactor vessels etc. that may lead to short but high impact emissions, during for example 0.5 hour every two weeks.
The regulators and the courts of appeal enthusiastically applied this guideline, as it assisted in reducing the emphasis on ambiguous judgments on the magnitude of the perceived nuisance of individual residents.
As a result of this guideline, the requirement for standardised, reproducible measurements became obvious, and resulted in a considerable effort to produce a standard for olfactometry, which was implemented in NVN2820:1993. Laboratories were then required to become accredited and the measurements were included as a method for impact assessment for licensing purposes and enforcement. (Note: The value of 0.5 ou_E/m^-3, referenced to 40 ppb/v n-butanol, is equal to 1 ge·m-3 or Dutch odour unit, that was referenced to 20 ppb/v nbutanol.)
In May 1994 the Minister responsible for the Environment published The Revised Odour Policy guideline document. After discussing the document in Parliament, the Minister reconsidered and decided to abandon the strict air quality target approach of this document.
The main argument was that, using common sense, it could not be right to apply the same air quality criterion, based on odour concentration, for odours as different in their potential to cause annoyance as bakeries and rendering plants.
This political development coincided with a more general policy shift in which the responsibility for environmental licensing was removed from the National ministry, by giving considerably more responsibilities to the Provincial and Municipal authorities.
The Minister outlined the policy shift in a letter to all Provincial Councils and Municipal Executive Councils dated June 30th, 1995, that has since become the key policy document for odours (Infomil, 2000).
The letter outlines the following principles to be used in the licensing process:
• If there is no existing annoyance, no odour impact reducing measures are required
• If there is annoyance, odour impact reduction measures have to be put in place on the principle of ALARA (As Low As Reasonably Achievable)
• The level of annoyance can be assessed using a number of methods, including survey methods (see section 5.2.2 Standardised Telephone Survey of the Living Environment:
TLO), complaints registration etc. For a number of defined sectors of industries (Category I processes) the acceptable level of annoyance is an issue contained in specific odour impact study documents.
• The admissible level of odour annoyance is to be determined by the responsible authority (i.e. provincial or municipal authorities, depending on the type of industrial activity)
The thinking behind the new approach is encapsulated in the distinction between two key concepts, first published in the NeR (Infomil, 2000):
• Admissible annoyance level (Acceptabel hinderniveau)
Criterion to be used in licensing, that is applied as national policy after 1995 as defined in the NeR, first published in 1996 (Infomil, 2000). The degree of annoyance that is admissible, as determined by the responsible authority. It is the overall result of an assessment that includes the following aspects: the history of the installation in its environment, the nature and appraisal of the odour, the complaints, additional information on the annoyance caused and (possible) emissions, technical and financial consequences of possible abatement measures, consequences for employment, etc. (letter on odour policy by the Minister responsible for the environment, 30 June 1995).
The admissible annoyance level is based on an environmental indication, qualification and/or quantification of annoyance level and an assessment and judgment of what is admissible taking into account local circumstances including aspects of public planning, social economic and financial/commercial factors (NeR, Infomil, 2000).
• Acceptable annoyance level (Aanvaardbaar hinderniveau)
Concept that forms a part of the admissible annoyance level, based on environmental indication, that does not include consideration of technical, financial, social-economic or public planning aspects (NeR, Infomil, 2000).
The Ministry did publish an overview of ‘suitable methods’ for assessing annoyance, but failed to provide an operational guideline to apply the ‘admissible level of odour annoyance’ concept.
The air quality criterion of C98, 1-hour < 5 ou_E/m^-3 , that had previously been proposed as a limit value, was mentioned in the letter, but as a ‘calculation value’ for assessing existing sources only. The concept of setting a national limit value for exposure to odour was abandoned. The letter emphasizes that odour exposure criteria will be used as a means to evaluate different odour management scenarios to assess the effectiveness of ALARA odour control rather than as a general target value for air quality in the licensing process.
The letter referred to the Netherlands Emissions Guideline as the source where Category-I industry studies would be made available. The NeR of 1996, that was updated in 2000, contains these industry specific studies:
• Infomil, (1996) NeR Nederlandse Emissie Richtlijn, Hindersystematiek Geur.
(Netherlands Emissions Guideline. Framework for odour nuisance), 1996, ISBN 90 76323 01 1
• Infomil, (2000) NeR Nederlandse Emissie Richtlijn. (Netherlands Emissions Guideline), 2000, ISBN 90 76323 01 1
The Category-I industries for which studies were carried out and agreed with the relevant industry associations are:
1) Composting of green waste
2) Potato processing industries
3) Meat packing and processing
4) Biscuit and pastry producing industry
5) Leather and tanning industry
6) Cocoa processing
7) Beer breweries
8) Composting of organic waste fraction (GFT)
9) Large bakeries and bread producers
10) Flavour and Fragrance industry
11) Asphalt production
12) Wastewater treatment works
13) Animal feed processing
14) Grass drying installations
15) Coffee roasting industries
16) Milk processing
In the National Emissions Guideline, specific chapters were included for sectors of industry known to cause odour annoyance. Each chapter that defined benchmarks for odour emissions, provided a Best Available Technique guidance, and in a number of cases defined ‘calculation values’ for odour exposure, in the well-known format of a concentration limit for the 98- percentile of 1-hourly calculated concentrations. These ‘calculation values’ were adopted in most cases, at least as a starting point, in licensing. For licence applications where such guidance was not available, alternative approaches were proposed by applicants and their advisors, or by provincial or municipal authorities.
In some cases, the operational air quality criterion for a licence application was derived from measurements that provide a measure of ‘annoyance potential, e.g. hedonic tone, intensity or comparative annoyance potential measurements.
Although the room to manoeuvre that was provided was considered in a positive light by those involved in the licensing process, it also led to considerably more uncertainty and discussion, which led in many cases to extensive negotiation between applicants and licensing authorities. Consequently, the risk of local and regional differences in environmental quality standards became a concern.
The technical commission advising on Environmental Impact Statements signalled in 1997 that insufficient consensus existed for the practical application of the current approach to establish an ‘acceptable level of annoyance’ As a result the Netherlands Standardisation Organisation NEN have advised to develop a method for quantitative assessment of ‘annoyance potential. A feasibility study was completed in early 2000, which concluded that a method for ‘annoyance potential as an attribute of odour could be developed and combined in a model that combined ‘hard’ assessments of odour concentration and odour annoyance and ‘soft’ risk assessments to arrive at a transparent assessment of ‘acceptable annoyance level. A similar conceptual framework is proposed in this report.
Once a standardised method for odour potential measurement is available, (final report planned for completion by the end of 2001), this is expected to lead to a review of policy, which may cause the pendulum to swing towards a slightly less flexible, more defined guideline.
It should be noted that in the typical ‘consensus culture’ of the Netherlands, the values that have been proposed in the NeR document for Category I industries, are generally applied without uch deviation.

United Kindom
Statute (criminal) law
Environmental Protection Act - Part 1

Part 1 of the Environmental Protection Act covers two discreet regimes of control:
• IPC – Integrated Pollution and Control for the most complex and polluting processes with emissions to air, land and water.
• LAAPC – Local authority pollution control for less polluting small processes covering emissions to air only.
In both cases, the principal vehicle of Part of Act is contained within the Prescribed Processes and Substances Regulations (1991). These regulations specify the industrial processes which are prescribed by the secretary of state and as such require an authorisation to operate.
In both cases, some odorants are classified as "prescribed substances" and will be subject to the requirement to use BATNEEC (Best Available Techniques Not entailing Excessive Cost) "for preventing the release of substances …… or where that is not practicable by such means, for reducing the release of such substances to a minimum and for rendering harmless any such substances which are so released…"
However, for Part B processes, the concept of Best Available Technique Not Entailing Excessive Cost (BATNEEC) is used to control the emissions of odours to air only and does not apply to odorants released from liquid or solid sources.
For other odorants which do not fall within Schedule 4 of The Environmental Protection (Prescribed Processes & Substances) Regulations 1991 (as amended) the requirement is for "rendering harmless any other substances which might cause harm if released into any environmental medium" applies - EPA'90 sec7(2)(a)(ii). This concept applies to Part A processes only and in this context, harm is offence to man's senses or harm to his property.
Sec 1(4) EPA'90.
Hence for both Part A and B processes regulated under Part 1 of the protection act, the regulating authorities main control is through the “authorisation” system, and setting of appropriate conditions, to control the activities and define precautions to be taken to be carried out in connection with or in consequence of the processes activities.
IPPC
The Integrated Pollution, Prevention and Control (IPPC) Directive, as implemented by the Pollution Prevention and Control Regulations 1999 stipulates that offensive odour emissions will be prevented or where that is not practicable, reduced in order to achieve a high level of protection of the environment as a whole. This approach is very similar in concept to the IPC system, however IPPC is much wider in both scope and coverage.
Those activities covered by IPPC are listed in Annex 1 to the Directive which has been implemented in domestic legislation by a schedule attached to the Pollution Prevention and Control Regulations. The regulation of those activities will be shared between the Environment Agency and the Local Authorities.
In addition, some activities currently covered by a waste management licence will fall within IPPC. These include:
• Any installation disposing of hazardous waste and some hazardous waste
recovery operations.
• Incinerators.
• Disposal of non-hazardous waste by physico-chemical or biological treatment.
• All landfills, other than inert landfills.
• Some sewage treatment works.
The enforcing authority, whether it be the Agency or Local Authorities, in issuing permits, must ensure that the ‘Best Available Techniques’ (BAT) are used to ensure that all appropriate measures are taken against pollution in particular by the application of BAT and that BAT is used as the basis for setting emission limit values or any other equivalent parameters or technical measures via the permit.
Landfill operations will need to meet the requirements of the Landfill Directive as well as the IPPC Regulations.
Town and Country Planning Act 1990
The Town and Country Planning Act 1990 specifies controls over development under planning law. The planning and pollution control systems, though separate, are complementary in that both are designed to protect the environment from the potential harm caused by development and operations, although with different objectives. The planning system complements the pollution control policies by regulating the location of development and the control of operations in order to avoid or minimise adverse effects on the land use and on the environment, i.e. to ensure serious detriment to the amenities of the locality does not occur.
Statutory Nuisance (section 79 of the Environmental Protection Act
1990, EPA)
The principal route to control odours arising from processes which cannot be regulated under IPC or LAAPC or waste management, is through Part III of the Environment Protection Act 1990. Section 79 of the Environmental Protection Act 1990 states that:
"A Statutory nuisance includes any dust, steam, smell or effluvia arising on industrial, trade or business premises which are prejudicial to health or a nuisance"
Under s79(1)(d) of the EPA, ‘any dust, steam, smell or other effluvia arising on industrial, trade or business premises and being prejudicial to health or a nuisance’ is a statutory nuisance for the purposes of Part III of the EPA.
Note that, unlike other provisions under this section, s79(1)(d) only applies to smells arising from ‘industrial, trade, or business premises’ - a smell cannot be a statutory nuisance if it is arising from a private home or a recreational activity. Similarly, a smell arising from contaminated land (s79(1A)) or military land (s79(2)) cannot be an s79 statutory nuisance.
Under s79 of the EPA a statutory nuisance is therefore either prejudicial to health OR a nuisance.
In this context, ‘Prejudicial to health’ is defined as meaning injurious, or likely to cause injury, to health. When determining if something is a nuisance, the relevant case law seems to follows the common law definition of nuisance (refer to section below).
It is the duty of the Local Authority to take steps against an operation or process causing a statutory nuisance. To prevent Statutory nuisance, the Local Authority must serve an abatement notice outlining the steps to be taken to prevent the statutory nuisance. The Local Authority must have regard to the Best Practicable Means (BPM). BPM is interpreted by reference to a number of provisions, which include:
a. ‘practicable’ means reasonably practicable having regard among other things to local conditions and circumstances, to the current state of technical knowledge and to the financial implications;
b. the means to be employed include the design, installation, maintenance and manner and periods of operation of plant and machinery, and the design, construction and maintenance of buildings and structures.
Statutory nuisance does not apply where proceedings to deal with the nuisance could be taken under Part I of EPA'90.
Common Law - Nuisance
The law of nuisance is concerned with the unlawful interference with a person’s use or enjoyment of land, or of some right over or in connection with it. In attempting to assess liability in a nuisance action, a balance is made between the reasonableness of the defendant’s activity and its impact upon the plaintiff’s proprietary rights.
In assessing the balance the courts will take into account a number of specific factors including the locality of the nuisance, the duration of the nuisance and any hypersensitivity on behalf of the plaintiff.
One of the balancing factors to be taken into account is the amount a nuisance can be ‘sensed’. The law does not take into account ‘trivial unpleasantness’. Nuisance is not actionable without proof of damage. The inconvenience has to be able to be ‘sensed’ by reasonable members of the public. It has to be capable of being smelt by people other than the defendant. Where one person senses a smell, that does not automatically mean an action can be founded. If a potential plaintiff (a ‘hypersensitive’ plaintiff) is particularly sensitive to one type of nuisance then it will not be actionable unless that nuisance would have affected a ‘reasonable’ person.
It is also necessary to take in to account the circumstances and character of the locality in which the complainant is living and any similar annoyances that exists or previously existed there.
A public nuisance is a nuisance that affects a wide class of the public in general. It is a criminal offence to cause a public nuisance. To prove public nuisance there is a need to show an effect over a wide class of the public.

Quantification of noise induced annoyance as related to current UK legislation
Nuisance arising from exposure to noise is generally regulated under the nuisance legislation

Relevant Literature
Absolute values are suggested as limits for purposes of legislation are proposed in number of documents. In addition, set methodologies for measuring noise and interpretation of results are outlined.
British Standard BS 4142:1997.
Those associated with noise legislation will be familiar with this document, which offers advice on the likelihood of receiving complaints of industrial noise affecting mixed residential and industrial areas. The assessment involves calculating the difference between the Background Sound Level (section 0) and the Rating Level (section 0). and the advice is as follows:
• Difference of =10dB
Complaints are likely and the greater the difference the greater the likelihood of complaints
• Difference of ˜5dB
Marginally significant
• Rating Level >10dB below Background Level
Insignificant
Olfactometry already assumes that all odour concentrations are above background. However, as the background level is not measured, this is merely a simplification rather than scientific and the measurand.
WHO – Guidelines for Community Noise
This document (Berglund, Lindvall, 1995) proposes that the noise should not be loud enough to give reasonable cause for annoyance to persons in the vicinity.
The guidelines suggest, inter alia, that:
• An outdoor LAeq greater than 50dB s likely to give moderate cause for annoyance in the daytime or evening
• An external night time level of LAeq of 45dB or less is required to prevent sleep disturbance.
These are continuous noise levels principally arising from road traffic.
It can be seen that the WHO guidelines simplify the criteria still further and hence are only general guidance, which should be used with caution..
Defining noise levels
The noise levels relevant to legislation are outlined in the documentation listed above. It is critical to note the relationship between the values given for the source in question and noise from other sources. The following definitions are taken from BS 4142:1997.
• LAeq,T
The LAeq,T is the value of the A-weighted sound pressure level in decibels of continuous steady sound, within the time period T, that has the same mean-squared sound pressure as a sound that varies with time.
• Background Sound Level
LA90,T is the A-weighted sound pressure level that is exceeded for 90% of the time interval T, measured using the time weighting F, and quited to the nearest whole number of decibels.
• Rating Level
A noise index – the equivalent continuous A-weighted sound pressure level during a specified time period with the addition of 5dB(A) for tonal or impulsive characteristics of the sound. (LAr, Tr)
It would only be possible to enforce the criteria above for perceived odorants if that which has been identified as causing nuisance was very strong. In addition, it is not possible to separate the main source odour (specific odour if related to terminology above) from the ambient odour in order to achieve the residual odour. The specific odour would be quantified using atmospheric dispersion modelling in practice, and the residual odour would be discounted.
This dispersion modelling would in effect give a rating level for odour concentration over time. In olfactometry the reference time interval is the time taken for one sample to be collected.

United States
In the United States, there is no odour policy at the federal level. The Environmental Protection Agency has engaged in odour related research until the early 1980’s which was then halted. The EPA has published a compilation of odour thresholds in 1992:
• US-EPA, (1992) Reference Guide to Odor Thresholds for Hazardous Air Pollutants Listed in the Clean Air Act Amendments of 1990, US Environmental Protection Agency Air Risk Information Support Center, (EPA600/R-92/047).
The method of odour measurement is not well standardised. A standard exists, generally called the ASTM Syringe method:
• ASTM D1391-57 (1972): Standard Method for Measurement of Odor in Atmospheres, Annual Book of ASTM Methods Part 23, Amer. Soc. Test. Mater., Philadelphia, Pa.
The ASTM syringe method for olfactometry is generally viewed as ineffective, and no new standard is being developed. Many odour thresholds in US publications indicate unrealistically high concentrations of the compound involved. The main cause is the practice of using very low flows of odorant mix in olfactometers, of 0.1 to 3 liter/minute, which is well below the normal human inhalation rate. A number of universities have now adopted the method as described in EN13725 ‘Air quality – Determination of odour concentration by dynamic olfactometry’. These universities are typically involved in research of agricultural livestock odours (Duke University, Iowa State University, the University of Minnesota, Purdue University). In addition wastewater treatment organisations use this method (Los Angeles County Sanitation District, Minnesota Metropolitan Council) (Mahin, 2001).
Regulation and management of odour related annoyance is a task that is carried out on the state or county level. There is a wide variety of approaches.
The main odour regulation issues are related to livestock operations and wastewater treatment.
The use of odour unit or dilution to threshold (D/T) limits is relatively common, but the values applied, averaging times, percentiles and methods of assessment vary considerably, as is illustrated in Table 16.
In the agricultural sector, odour complaints are a topical issue, in the light of considerable centralisation of production in more corporate business structures. The US Department of Agriculture task force on air quality recently issued a report. The American Society of Agricultural Engineering published a code of practice:
• ASAE, Control of Manure Odours, Engineering Practice 379.1.
That recommends setback distances to separate livestock units from residents between 800 m for neighbouring residences and 1600 m for residential development.
The State of Minnesota has a feedlot air quality programme, in which the Minnesota Pollution Control Agency is appointed to monitor air quality around feedlots though measurement of Hydrogen Sulphide concentrations in air. The monitoring programme involved 137 feedlots, of which 24 were found to have the potential to exceed the air quality criterion:
• 30 ppb/v H2S as a 30 minute average not to be exceeded on more than 2 days in a five day period (this would be at least 60 ou_E/m^-3, based on an odour threshold for H2S of 0.5 ppb/v, not taking into account other odorants)
• 50 ppb/v H2S as a 30 minute average not to be exceeded on more than 2 times in a year.
The Livestock Odour Task Force was established in Minnesota in 1995, and has recommended a system to rate odour emission potential from livestock operations: the Odour From Feedlots – Setback Estimation Tool (OFFSET). This tool is now being piloted for use in determining planning decisions.
In North Carolina, the Attorney General, the top legal official in the state, reached an agreement on July 25, 2000, with Smithfields Food, the dominant pig producer in the state with 276 company owned farms. The agreement provides for elimination of all open-air anaerobic slurry lagoons and spray fields on these farms (Mahin, 2001). To achieve this a detailed research plan was defined, with the Smithfield Foods company providing significant funding of 15 million dollar. The programme is spearheaded by the College of Agriculture and Life Sciences at North Carolina State University.
(Williams, C.M., (2001) Technologies to address air quality issues impacting animal agriculture, In: Proceedings of the 1st IWA International Conference on Odour and VOC’s:
Measurement, Regulation and Control Techniques, University of New South Wales, Sydney, March 25-28, 2001, ed. J. Jiang, International Water Association, ISBN 0 7 334 1769 8.)

Other countries
Laws and regulations aimed at limiting the occurrence of nuisance have been in force in many countries for a significant lengths of time. However, regulations aimed specifically at regulating odour-induced annoyance are a more modern feature. The first odour regulations in Europe started to appear in the 1970’s, typically defining minimum setback distances for agricultural livestock operations (van Harreveld, 1991, Mahin, 2001). In recent years many states and nations have proposed and, in some cases, implemented policy and regulations specifically aimed at regulating the impact of odours from commercial activities, both agricultural and industrial.
In general terms, there are three basic approaches to regulating odours:
1) Qualitative regulatory frameworks, that define environmental quality in general terms, such as
a) absence of nuisance,
b) odours not detrimental to the amenity,
c) no justified complaints, as judged by officials
d) etc.
2) Quantitative regulatory frameworks, that define ambient air quality criteria. Such criteria
may use:
a) odour concentration, usually determined as a frequency of exceedence of concentration limits as determined using dispersion modelling,
b) ambient concentration limits of specific odorous compounds (e.g. Hydrogen Sulphide)
c) Frequency of detection of odours using field panels
3) Standard operational requirements for specific activities, such as:
a) Setback distances for livestock housing units
b) Requirements for standard abatement techniques (i.e. defined using concepts similar to BATNEEC) combined with minimum setback distances at different production capacity levels, applied to specific industrial or agricultural activities.
In the following sections different approaches that are in place or have been proposed are identified and described.