Final Phase of Ontario Regulation 419/05: Air Pollution – Local Air Quality

Posted by:
Beth Rhyno
Senior Environmental Engineer
Guelph, ON, Canada

Ontario Regulation 419/05

The Ontario Ministry of Environment, Conservation and Parks (MECP) is changing the compliance regulations in regards to air quality contaminants that are released from local industrial and commercial facilities. If your business releases contaminants into the air, then they are required, by law, to comply with the new regulations of Ontario Regulation 419/05: Air Pollution – Local Air Quality.

We are quickly approaching the final implementation phase of the amendments to O.Reg. 419 in effect as of 1 February 2020; this is the final requirement of multiple year phase-ins and requires the final classification of facilities and industrial operations in Ontario to comply with new air quality standards. Various industrial groups were required to comply with these updated models by February 1st, 2010, other facilities had until February 1st, 2013, and now all facilities in Ontario must comply by February 1st, 2020 (10 weeks from the time of this post).

What are the Changes?

Facilities and operations are now required to demonstrate compliance with the newest point of impingement standards/limits by utilizing MECP approved versions of the more sophisticated dispersion modelling software (AERMOD and ASHREA).

There is a significant change with respect to the air quality standards with the move from Schedule 2 - 1/2hr averaging periods for air quality standards to use of Schedule 3 air quality standards having variable averaging times and for some contaminants stricter emission rates. Implementing the new air dispersion modelling software and evaluating against the new air quality standards may result in the facility/operations no longer meeting compliance even though the same operational parameters and scenarios have been maintained all along.

Where do I start?

SLR is advising clients to start remodeling their site activities and complete the compliance revisions for demonstrated proof of compliance by revising the site Emission and Summary Dispersion Modeling (ESDM) reports as soon as possible. Facing potential compliance issues now is better than waiting until the last minute. It is especially important to complete this earlier in cases where site specific meteorological data is required due to the delay in receiving specific MECP data (up to two months or more). Better to have the revised AERMOD modeling and ESDM report completed now than scramble for mitigation just before the deadline in late January 2020.

If you are unsure of your facility or operation compliance status is or what standards it should be compared to contact SLR and one of our experts will be happy to provide you that information and start your compliance due diligence program.


Beth Rhyno is an Senior Environmental Engineer who specializes in industrial compliance, implementation and project management.




Air Quality, Environmental Compliance Approval, Ontario Regulation, 419/05, MECP, Environmental Consulting, Ontario, Air Regulations