Air emissions management

Directive 39 Update – New benzene emission limits in Alberta

Earlier in 2013, the Alberta Energy Regulator or AER (previously ERCB) released a revised Directive 39 (Benzene Emissions from Glycol Dehydrators).

At this time, these changes do not apply to BC units as regulated by the OGC. The OGC will publish an information letter if they deem that changes are warranted.

Changes to AER Directive 39 include the due date for submitting the inventory list (now May 1), and the requirement for a Decision Tree Analysis, which has been changed to a recommendation.

The key change is the phase in of new benzene emission limits, particularly for units less than 750 m from residents. The first change applies in 2014, for units less than 250 m from residents:

  • The emissions limit for units less than 100 m from residents is 0.0 tonnes/yr.
  • The emissions limit for units 101-250 m from residents is 0.1 tonnes/yr.
  • The emissions limit for units less than 250 m, with a flare or incinerator, is 1.0 tonnes/yr.
  • Emissions are calculated to 2 decimal places and displayed to one decimal place. Therefore a unit with 0.04 tonnes/yr benzene emissions is rounded to 0.0 tonnes/yr.
  • Distance to residents is calculated from the source, which includes (but is not limited to):
  • Still overhead, if there are no controls
  • Flare stack, if still overheads are ultimately flared
  • Condenser tank vent, if still overheads are routed to the tank.

The resident boundary has not been explicitly clarified, and we expect a clarification from the ERCB on this matter.

The implementation schedule, from AER Directive 39, is shown below:

D39 Limits

Process Ecology has updated our Benzene Advisor system to use the 2014 emissions limits, and we will ensure that further emissions limits which will be implemented 2015-2018 will be employed as they become applicable.

If you have further questions regarding AER Directive 39, you may contact us at



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