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CONTROLLING EXPOSURE

R5.48-1 Controlling Exposure - Exposure Limits
R5.54-1 Controlling Exposure - Exposure Control Plan

Policies Part 5 - Controlling Exposure

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R5.48-1
Controlling Exposure - Exposure Limits

BACKGROUND
1. Explanatory Notes
Section 5.48 provides established limits for a worker's exposure to hazardous chemical substances. Generally, these exposure limits are established according to the Threshold Limit Values ("TLVs") adopted by the American Conference of Governmental Industrial Hygienists ("ACGIH"). However, the Board has authority to make exceptions and adopt exposure limits for specific chemical substances that are not consistent with the TLVs established by the ACGIH. This policy sets out those exceptions.

2. The OHSR
Section 5.48:

Except as otherwise determined by the Board, the employer must ensure that no worker is exposed to a substance that exceeds the ceiling limit, short-term exposure limit, or 8-hour TWA limit prescribed by ACGIH.

Section 5.57:

(1) If a substance identified as any of the following is present in the workplace, the employer must replace it, if practicable, with a material which reduces the risk to workers:

(a) ACGIH A1 or A2, or IARC 1, 2A or 2B carcinogen;

(b) ACGIH reproductive toxin;

(c) ACGIH sensitizer;

(d) ACGIH L endnote.

(2) If it is not practicable to substitute a material which reduces the risk to workers, in accordance with subsection (1), the employer must implement an exposure control plan to maintain workers' exposure as low as reasonably achievable below the exposure limit established under section 5.48.

(3) The exposure control plan must meet the requirements of section 5.54.

3. Preamble to Policy
The following is a preamble to be applied to those exposure limits developed by the Board as an exception to the TLVs established by the ACGIH:

An exposure limit is a maximum allowed airborne concentration and is not intended to represent a fine line between safe and harmful conditions. In determining an exposure limit, it is not possible to take into account all factors that could influence the effect that exposure to the substance may have on an individual worker. Therefore, for all hazardous substances, regardless of any assigned exposure limit, the guiding principle is elimination of exposure or reduction to the lowest level that is reasonably achievable below the exposure limit.

Due to a wide variation in individual susceptibility, some workers may experience discomfort from some substances at concentrations at or below the exposure limit. Others may be affected more seriously by aggravation of a pre-existing condition, or by development of an occupational disease. Furthermore, other workplace contaminants may affect an individual's response. The effects of combined chemical exposures are often unknown or poorly defined.

POLICY
1. Table of Exposure Limits for Excluded Substances

As presented in the table below, the Board has determined exposure limits for the following specific substances that differ from the TLVs established by the ACGIH. For solid and liquid particulate matter, except where the terms inhalable, thoracic, or respirable particulate mass are used, the exposure limits listed in the table below are expressed in terms of "total particulate matter".

(E) = the value is for particulate matter containing no asbestos and less than 1% crystalline silica
(N) = the 8-hour TWA listed in the Table is for the total dust. The substance also has an 8-hour TWA of 3 mg/m³ for the respirable fraction
(L) = exposure by all routes should be carefully controlled to levels as low as possible

2. Dusts
The Board categorizes particulates that are insoluble or poorly soluble in water and do not cause toxic effects other than by inflammation or the mechanism of "lung overload", as "nuisance dusts".

A "nuisance dust" will have an exposure limit or TLV of 10 mg/m³ for total particulate. It is recognized that the respirable fraction of "nuisance dusts" may also be measured. The equivalent exposure limit for respirable particulate is 3 mg/m³. Respirable particulate refers to the fraction of inhaled dust that is capable of passing through the upper respiratory tract to the gas exchange region of the lung. Total particulate refers to a wide range of particle sizes capable of being deposited in the various regions of the respiratory tract.

R5.54-1
Controlling Exposure - Exposure Control Plan

BACKGROUND
1. Explanatory Notes
Section 5.54 sets out the requirement for an exposure control plan in certain circumstances and the necessary elements if an exposure control plan is required. Among those elements is health monitoring under section 5.54(2)(f).

2. The OHSR
Section 5.54:

(1) An exposure control plan must be implemented when

(a) exposure monitoring under section 5.53(3) indicates that a worker is or may be exposed to an air contaminant in excess of 50% of its exposure limit,

(b) measurement is not possible at 50% of the applicable exposure limit, or

(c) otherwise required by this Regulation.

(2) The exposure control plan must incorporate the following elements:

(a) a statement of purpose and responsibilities;

(b) risk identification, assessment and control;

(c) education and training;

(d) written work procedures, when required;

(e) hygiene facilities and decontamination procedures, when required;

(f) health monitoring, when required;

(g) documentation, when required.

(3) The plan must be reviewed at least annually and updated as necessary by the employer, in consultation with the joint committee or the worker health and safety representative, as applicable.

POLICY
At the request of persons outside the Board or Board staff, the Board may arrange for samples to be analyzed as part of a health monitoring program under section 5.54(2)(f). The Board will have the results organized into broad categories of body burden levels and reported to the person who made the request and to Board staff and industry representatives concerned with the particular program.

The actual body burden levels of individuals are confidential and will only be revealed to a worker if the worker inquires, and to anyone else with the worker's written authorization. Questions regarding specific analysis results should be referred to the Board staff concerned with the particular program.