Setting B1 values

In general, B1 values are standards and guideline values used to protect the human health and the natural environment against adverse effects. Existing ministry processes for development of standards and guidelines and associated consultation processes remain unchanged. Generally, the B1 values are numerically the same as Ambient Air Quality Criteria (AAQCs); however, B1 values and AAQCs are used differently. B1 values are intended to assess the contribution of a contaminant to air by a regulated facility whereas AAQCs are used to assess general air quality in relation to all sources, not just emissions from a single facility. A separate list of AAQCs is available in the document Ontario’s Ambient Air Quality Criteria.

Ministry expectations

In the context of an Environment Compliance Approval (ECA), the Director under section 9 of the Environmental Protection Act (EPA) may exercise his or her discretion to refuse to issue an ECA if he or she considers it to be necessary for the purposes of protecting and conserving the natural environment. Accordingly, it is expected that an ESDM report prepared for the purpose of section 22 of O. Reg. 419/05 will demonstrate that the concentration of a contaminant is at or below the B1 value for the contaminant. Please note that this does not apply to facilities operating under a site-specific standard for a specific contaminant.

An EASR ESDM report prepared under O. Reg. 1/17 must be signed and sealed by a licensed engineering practitioner and must demonstrate that the concentration of each contaminant discharged or proposed to be discharged from the facility is at or below the B1 value for the contaminant. Further, at all times when engaging in an activity prescribed by O. Reg. 1/17, the person must ensure that the concentration of a contaminant is at or below the B1 value for the contaminant – to exceed a B1 value is an offence.

Regardless of whether an activity is governed by section 9 of the EPA (i.e. for ECAs), section 20.21 of the EPA (i.e. for EASR) or exempt from section 9 of the EPA, discharges from the facility must still comply with O. Reg. 419/05.

Exceedance of a B1 value identifies the need for a facility to take action under O. Reg. 419/05. Such action would include notification of the ministry under section 28 of O. Reg. 419/05 and the submission of an abatement plan within 30 days. Note that if the B1 value is an air standard set out in O. Reg. 419/05, the facility may be able to request a site-specific standard or register to a sector-based technical standard, if one exists. If the B1 value is a guideline, facilities may also register for a technical standard if one exists for that facility in that sector.

Note that for contaminants with multiple B1 values, all values must be used for assessment purposes because each represents a different type of effect linked to a particular averaging period. The ACB List sets out some B1 values that have an annual averaging period. For these values, the ministry expects a comparison also be made to Assessment Values (see Table 2) for the purpose of addressing short-term periods of elevated exposure. The annual assessment values (AAVs) and daily assessment values (DAVs) are used as supplementary information to help ensure no adverse effect is likely to occur as a result of the discharge of a contaminant with an annual standard. For more information please see the Technical bulletin: Using assessment values for contaminants with annual air standards.

Connections between air contaminants benchmarks list and Ontario Regulation 419/05

Some of the values set out in the ACB List are air standards that are set out in O. Reg. 419/05. Any discrepancy between the ACB list and O. Reg. 419/05 will be resolved in favour of the regulation.

Previous versions (v.1 and v.2) of the ACB List contained both air standards used by facilities to which section 19 of O. Reg. 419/05 was applied (Schedule 2 air standards with half-hour averaging time period), and air standards with variable averaging periods used by facilities subject to section 20 of O. Reg. 419/05 (Schedule 3 air standards). As specified in O. Reg. 419/05, as of February 1, 2020, all facilities in Ontario are required to comply with section 20 of O. Reg. 419/05 (Schedule 3 standards and the newer models set out in section 6 the regulation). Schedule 2 standards were phased out and therefore, removed from the ACB List.

Although the ACB List sets out concentrations for contaminants that are standards in O. Reg. 419/05, there are certain circumstances where a facility may have another compliance approach such as complying with a site-specific standard or a technical standard. A facility that has approval for a site-specific standard would assess compliance for that contaminant against its site-specific standard. A facility that is registered to a technical standard with respect to a contaminant, does not have to comply with the concentration-based air standard for the contaminant if all of the sources of the contaminant at that facility are addressed in one or more technical standards and the facility is registered for all of these technical standards. In these cases, facilities are not required to have an ESDM report for these contaminants.

The ACB List also identifies which contaminants have an upper risk threshold (URT) listed in Schedule 6 of O. Reg. 419/05. URTs are neither standards nor screening levels. URTs are concentrations, which if exceeded at a point of impingement, require timely actions (i.e. immediate notification to the ministry in writing, and submission of an ESDM report for the contaminant that was exceeded within 3 months). For more information, please refer to section 30 of O. Reg. 419/05 and the Guideline A-12: Guideline for the implementation of Air Standards in Ontario document.