Southwest Environmental Limited
Suite 2201, 250 Yonge Street, Toronto, Ontario , Canada M5B 2L7

Phone: 647 794 0233             Email:

Environmental Consultancy Services to Industry, Business and Individuals

Dispersion Modelling Report 

SWEL can provide a Dispersion Modelling Report in support of your CofA.

The key guidance for Dispersion Modelling in (by example) Ontario comes from the Ministry of Environment. A checklist is also published to make sure that consultants include all the relevant information! Legal driver is Ontario Regulation 419/05.

Other provinces of Canada have similar guidance, although in some cases it is not as extensive. SWEL can produce dispersion modelling reports across Canada. There are two main parts to an ESDM report that is the Emission Summary and the Dispersion Modelling.

A facility which emits only noise as a contaminant is not required to prepare an ESDM report. All ESDM reports are required to be prepared in accordance with section 26 of the Regulation. Section 26 sets out the minimum requirements to documenting compliance with MOE POI Limits. Chapter 3 of this Procedure Document sets out the minimum requirements for the contents of an ESDM report, as set out in section 26 of the Regulation. Dispersion Modelling also required for CofA (Certificate of Approval) were emissions other than noise will be released.

Emission Summary

Assess the significance of sources and contaminants and eliminate negligible ones from further analysis. The ESDM report must provide an explanation of how it was determined that an amount of a contaminant discharged is negligible and/or that a source discharges a contaminant in a negligible amount.

For each contaminant, describe the facility operating condition(s) that results in the actual maximum POI concentration that occurred within the last year or that corresponds to the maximum POI concentration that the facility is capable of. Operating conditions must correspond to the averaging period for each applicable MOE POI Limit. Estimate emission rates; describe the estimating methodology for each significant contaminant or group of similar contaminants; and classify how accurately each method is in estimating emissions.

Dispersion Modelling

This chapter should include: - a description of the local land use conditions if MOE approved regional meteorological data has been refined to reflect local land use; - identification of the approved dispersion model that was used and a description of the way in which the approved dispersion model was used that is sufficient to show compliance with sections 9 to 17 of the Regulation (guidance and a suggested summary table format is provided in Chapter 10 of this Procedure Document); and - a description of the terrain data that was employed if according to section 16, terrain data is required.

Who is required to carry out ESDM Report?

There are numerous reasons why a responsible person may have to prepare an ESDM report.


Stands for North American Industry Classification System codes maintained for Canada by Statistics Canada. For example below are some NAICS Codes as defined:


NAICS Code Description

2122 Metal Ore Mining
331 Primary Metal Manufacturing
332 Fabricated Metal Product Manufacturing

Description of a proposed facility can be used in determining scope of ESDR report, for example the below sectors listed are unlikely to produce fugitive metals emissions.

POI Limits

The concentration of a contaminant at a specific POI is a function of a variety of parameters including meteorological conditions in the vicinity of the source and the POI, contaminant emission rate(s) and physical characteristics of the source and terrain in the vicinity of both the source and receptor. Atmospheric dispersion models use a combination of data inputs for these parameters in conjunction with mathematical algorithms that describe both the temporal and spatial variation of contaminants as they move away from the source.

Not all Contaminants have POI Limits. If a facility emits a contaminant that does not have an MOE POI Limit, it is strongly recommended that the modelled POI concentration be compared to the JSL list. A contaminant that has a POI concentration below its respective JSL does not require further assessment but must be documented in the Emission Summary Table of the ESDM Report. If the JSL is exceeded, or the contaminant is not listed on the JSL, further assessment must be done. If the ESDM Report is submitted as part of the CofA process, this further assessment will occur with input from MOE scientists as part of the MOE’s review and acceptance of a Maximum Ground Level Concentration. This value then appears in the Emission Summary Table upon completion of the review process.


Screening out sources that are low risk.  Sources that, in combination, represent less than 5% of total property-wide emissions of a contaminant can, in many cases, be considered negligible sources.