2009 NASM Odour Guide for Ontario Regulation 267/03 made under the Nutrient Management Act, 2002

Part 4 - Odour Categories

Table of Contents

  1. Basic Method: NASM Odour Category Table
  2. Procedure to Assign or Reassess and Assign NASM Odour Category
  3. Odour Assessment Test

The odour category determines the NASM application setback requirements to individual dwellings, residential areas and land with commercial, community or institutional uses. The regulation sets out three categories that are related to odour. These are odour category 1, (OC1), odour category 2 (OC2), and odour category 3 (OC3). Each category in the regulation is defined as follows:

  1. OC1, when used in reference to NASM, means that it has an odour detection threshold of less than 500 odour units (ou) per cubic metre (m3) as determined in accordance with this guide)
  2. OC2, when used in reference to NASM, means that it has an odour detection threshold equal to or greater than 500 odour units (ou) per cubic metre (m3) and less than 1500 odour units (ou) per cubic metre (m3) as determined in accordance with this guide and;
  3. OC3, when used in reference to NASM, means that it has an odour detection threshold equal to or greater than 1500 odour units (ou) per cubic metre (m3) and less than 4500 odour units (ou) per cubic metre (m3) as determined in accordance with this guide and.

O.Reg 267/03 does not allow NASM to be applied to agricultural land if its odour detection threshold exceeds that of OC3 NASM (O. Reg 267/03 s8.2).

In the development of a NASM Plan, the certified NASM plan developer must determine the odour category of the NASM using one of 3 methods set out in this guide.

4.1 Basic Method: NASM Odour Category Table (Section 5 of this Guide)

This method to be used in cases where the NASM is listed in the NASM Odour Category Table, Table 3 of the document titled Nutrient Management Tables and the proponent is in agreement with the categorization.

If the NASM is listed in the NASM Odour Category Table, but the specified odour detection threshold is believed by the proponent to be different than the odour detection threshold as set out in the heading under which the NASM is listed, one of the other methods listed in sections 6, 7 or 8 can be used to determine the category.

4.2 Procedure to Assign or Reassess and Assign NASM Odour Category (Director's Assignment) (Section 6 of this Guide)

This method allows the Director to assign an odour category to a material not listed in the NASM Odour Category Table based on his/her knowledge of the NASM and similar types of NASM.

This method may also apply where the proponent and the Director do not agree on the assigned odour category as outlined in the Basic Method or in cases where the proponent and the Director do not agree on the revised NASM odour category. The odour assessment test process described in sections 7 and 8 of the guide can then be used to assist in determining the NASM odour category.

4.3 Odour Assessment Test (Section 7 and Section 8 of this Guide)

This method can be used where the proponent and the Director do not agree on the NASM odour category, the NASM odour category can be determined using the Odour Assessment Test process described in section 7 and 8 of the guide.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 14 September 2009
Last Reviewed: 14 September 2009