Today, we released AERH2S, a model for determining emergency planning zones (EPZ) for all sour well and pipeline applications. AERH2S is available for use immediately and is required for Directive 056: Energy Development Applications and Schedules, effective January 1, 2026.
AERH2S is an updated and renamed version of our existing model, ERCBH2S, first released in 2008. This version of the model includes an updated program that functions on modern computer systems, updated scientific parameters, a refresh of current meteorological data, and an updated approach to selecting an EPZ from the modelled scenarios. Changes to the model do not indicate a change in risk level regarding hydrogen sulphide (H2S). The calculated EPZ is a planning tool only. Approval holders are required to respond to the full extent of any emergency, even if it extends beyond the calculated EPZ.
To ensure an effective transition to AERH2S and recognizing the ongoing efficacy of ERCBH2S, we have adopted a phased implementation for the release of the revised model. Until further notice, use of AERH2S is optional for Directive 071: Emergency Preparedness and Response updates to EPZs established before January 1, 2026. ERCBH2S remains effective, available, and accepted by the AER for existing EPZs. The use of AERH2S under Directive 071 is required for any Directive 056 applications made after January 1, 2026, including amendment applications.
With AERH2S, we have also released an updated technical reference document and user guide. The AERH2S model and the support materials are available on the AER website under Systems and Tools.
Refer to the AERH2S user guide for methods to transfer existing data from ERCBH2S to AERH2S.
Send any questions regarding this bulletin to aerepzmodel.questions@aer.ca.
