Guideline to address odour mixtures in Ontario

ERO number
Notice type
Posted by
Ministry of the Environment, Conservation and Parks
Notice stage
Proposal Updated
Proposal posted
Comment period
May 4, 2021 - August 6, 2021 (94 days) Closed
Last updated

Update Announcement

On July 2, 2021, we extended the comment period for this proposal notice for another 34 days (to August 6, 2021) based on feedback and requests received by the ministry.

This consultation was open from:

May 4, 2021
to August 6, 2021

Proposal summary

Ontario is proposing guidance on how the Ministry of the Environment, Conservation and Parks, and the regulated community can anticipate, prevent and address odour issues that could be of concern to local residences.

Proposal details

Purpose of proposed odour guidance

Ontario is protecting the health of communities and our environment by taking a proactive, preventative approach to managing odour emissions.

We are proposing guidance on how industrial facilities, development proponents and other members of the regulated community can anticipate, prevent, and address odour issues that could be of concern to local residents.

The guidance would help ensure there is:

  • less regulatory uncertainty for facilities
  • better coordination with land planning decisions
  • more effective remediation of issues caused by odour mixtures

Although odorous impacts may be caused by a single contaminant, in many cases they are caused by a mixture of contaminants. The Ministry of the Environment, Conservation and Parks (the “ministry”) publishes odour-based standards (or other benchmarks) under the Local Air Quality Regulation (Ontario Regulation 419/05). Odour mixtures (total odour) are not specifically addressed in the local air quality regulation.

Our proposed guidance will provide more clarity on how to identify, prevent, manage, and remediate human health and environmental impacts caused by emitted odour. It includes:

  • clarification on the requirements for potentially odorous facilities applying for an Environmental Compliance Approval (ECA) under section 20.2 of the Environmental Protection Act
  • clarification for facilities preparing an Odour Study required by the Renewable Energy Approvals Regulation (Ontario Regulation 359/09)
  • tools to more effectively anticipate and prevent odour issues for new sources of odour and speed up remediation efforts
  • a process for assessing, mitigating and minimizing odour impacts when a new development is proposed, which supports the proposed Land Use Compatibility Guideline
  • additional resources for facilities when assessing odours or when preparing a Technology Benchmarking Report for odour
  • considerations for laboratories in Ontario that assess odour

By using this guidance, facilities will be able to identify potential odour sources before they are operational and speed up remediation efforts. They will also have best practices and recommendations available to help them mitigate odorous sources over time.

Other information – proposed phase-in period

We will consider comments on this proposal when finalizing Ontario’s guidance for odour mixtures. We are proposing that the environmental compliance approval application requirements outlined in this proposal be phased in 6 months when adopted.

Other information – development of additional guidance and tools

To assist persons in completing the required odour work for an Environmental Compliance Approval or Renewable Energy Approval application, the ministry has prepared or plans to prepare the following additional guidance and tools to complement the proposed odour guideline:

1) Technical bulletin – Methodology for completing an odour assessment for odour mixtures

The Technical Bulletin for Odour Assessment provides guidance for a facility when completing an odour assessment, including estimating odour emissions, identifying dominant sources, analyzing odour samples or performing air dispersion modelling for odorous mixtures. This proposed technical bulletin is included with this proposal notice for comment.

2) Screening form

The screening form would assist facilities with determining if any additional odour work is required for submission with the Environmental Compliance Approval application. The screening form would be considered a preliminary odour assessment and would assist facilities in determining what additional documentation or assessment is required with their application. The screening form would function similarly to the existing ‘odour screening report form’ found on the ministry’s website.

3) Odour technology benchmarking report

The example odour technology benchmarking report would demonstrate the type of information and report sections expected when completing an odour technology benchmarking report. We anticipate that the example odour technology benchmarking report would also reduce some of the effort and cost for facilities that are expected to complete odour technology benchmarking reports.

4) Technical bulletins outlining minimum expectations

These additional technical bulletins would provide minimum expectations for certain odorous activities and processes to encourage facilities to implement best practices and controls to reduce odour emissions.

We would develop these technical bulletins over time. The decision to develop a technical bulletin would consider factors such as the nature of the activity or process, the volume of ECA applications expected, the need to address challenging issues, etc. We intend to share draft technical bulletins, with stakeholders for their input before they are finalized. Once published, facilities could refer to the technical bulletins when considering odour controls.

Other information – odour analysis laboratory accreditation

Currently, all odour laboratories in Ontario are expected to follow the European Standard EN 13725:2003 in conjunction with provisions outlined within the Ontario Source Testing Code when analyzing odour samples. However, there is no generally accepted odour lab accreditation currently in place in Ontario.

To ensure the highest quality of results when odour laboratories analyze odour samples, we propose to work with accreditation organizations to develop specific quality requirements for Ontario’s odour laboratories.

After a phase-in period following publication of these specific quality requirements, we propose that all odour samples used for source assessments be analyzed by an accredited odour laboratory. The phase-in period is proposed to be two years after quality requirements are published to allow time for all interested odour laboratories to become accredited.

Other information – updating existing guidance

If the proposed odour guideline is finalized, we would update the following guidance documents with respect to odour:

1) Guide to applying for an Environmental Compliance Approval (ECA)

The ECA guide outlines the requirements for persons applying for an ECA application, including odour-related requirements. As part of this initiative, we propose that the ECA guide would be updated to align with requirements in the odour guideline once it has been finalized. For instance, Odour Impact Assessments or Odour Management and Control Plans for ECA applications for waste disposal sites (such as composting facilities and landfills, etc.) may no longer be required.

The ECA guide would also be updated to include the odour guideline requirements for pre-consultation. The ECA guide already includes recommendations for pre-submission meetings, and the update will harmonize pre-submission requirements so that multiple meetings are not required for one ECA submission.

2) Checklist for technical requirements for a complete ECA submission

This checklist would also be updated to reflect the odour guideline once is has been finalized.

3) Technical Guide to Renewable Energy Approvals

We propose that the Technical Guide to Renewable Energy Approvals be updated to indicate that bio-energy facilities will be required to submit a best management practices plan (BMPP) and odour technology benchmarking report (OTBR) with their application to satisfy the requirements of an Odour Study Report.

Concurrent with this posting, the ministry is consulting on a draft land use compatibility guideline and a new draft compliance policy. See the links below for additional information on these postings.

Other public consultation opportunities

As described above, if the proposed odour guideline is finalized, we anticipate developing additional resources in the form of technical bulletins or example reports for facilities when assessing odours or when preparing a Technology Benchmarking Report for odour. Anyone interested in reviewing these additional resources/tools to provide comments once completed should contact Sean Avery, Air Pollution Control Engineer, Technical Assessment and Standards Development Branch, We intend to seek input before the additional tools and guidance documents are completed.


Commenting is now closed.

The comment period was from May 4, 2021
to August 6, 2021

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Sean Avery

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Technical Assessment and Standards Development Branch

40 St. Clair Avenue West
7th floor
Toronto, ON
M4V 1M2

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