OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 1 Definitions and General Application

Section 1 Definitions

A number of words and terms are used in the Occupational Health and Safety Code (OHS Code) and are defined in this section. Understanding these words and terms is key to being able to use the OHS Code. Only those definitions that appear to require additional explanation are shown below.

"abnormal audiogram"

An audiogram is considered abnormal when a worker experiences significant hearing loss. Three criteria are used to determine if hearing loss is significant:

(1) if the hearing threshold level in either ear is more than 25 dB at 500, 1000 or 2000 Hz;

(2) if the hearing threshold level in either ear is more than 60 dB at the selected frequencies of 3000, 4000, or 6000 Hz. If the audiogram reads 25 dB at 3000 Hz, 50 dB at 4000 Hz and 65 dB at 6000 Hz it is an abnormal audiogram; and

(3) if there is a one-sided hearing loss with the difference between the average of the better ear's threshold values measured at 3000, 4000 and 6000 Hz and the average of the other ear's threshold values measured at 3000, 4000, and 6000 Hz exceeds 30 dB. As shown in the example below, the results of the audiogram for the right ear and left ear are averaged for the frequencies at 3000, 4000 and 6000 Hz. If the difference between the averages for the right ear and left ear is more than 30 dB, the worker is considered to have abnormal hearing.

Example: The following hearing threshold results were measured for a particular worker.

Hearing Threshold (dB)


Left Ear

Right Ear

3000 Hz



4000 Hz



6000 Hz






In this example, the difference in threshold between the better ear (left) and the poorer ear (right) is 35 dB. This is an abnormal audiogram.

"abnormal shift"

An audiogram is considered to be an abnormal threshold shift if there is a change of 15dB or more in either ear at two consecutive test frequencies at 1000, 2000, 3000, 4000 or 6000 Hz when it is compared with the worker's baseline test.


"Act" refers to Alberta's Occupational Health and Safety Act. The OHS Act describes obligations and duties that serve to protect and promote the occupational health and safety of workers throughout Alberta. It describes the rights and responsibilities of employers, workers, and others connected with the work site. The OHS Code derives its authority from the OHS Act and together with the OHS Regulation (AR 62/2003), states the rules applicable to occupational health and safety at Alberta workplaces.

For more information

OHS Act, Regulation and Code
The complete text of the OHS Act, OHS Regulation and OHS Code

"asbestos waste"

Materials considered to be asbestos waste are those having a high probability of releasing airborne asbestos fibres when handled. This includes asbestos-containing materials discarded from asbestos abatement projects and the disposable protective clothing worn by workers during those projects.


An audiometer is an instrument used to test hearing. The American National Standards Institute (ANSI) standard mentioned in the definition covers instruments that are designed primarily for the testing of hearing. The purpose of the standard is to ensure that tests of hearing ability, performed with different instruments complying with the standard, give essentially the same results under comparable conditions. The results must represent a good comparison between the hearing in the ear tested and the reference threshold of hearing. The standard applies to six types of instruments that are classified according to the type of test signal they generate (pure tone, speech or both), their mode of operation, and the complexity or range of auditory functions they test.

"audiometric technician"

The OHS Code requires an audiometric technician to pass an approved audiometric technical course. Audiometric technician courses may only be provided by an agency that has entered into an agreement with the Director of Medical Services. A Director of Medical Services is a member of the staff of Alberta Human Services, appointed by the Minister under section 5 of the OHS Act.

The audiometric technician administers occupational hearing tests, classifies audiometric data and conducts post test counseling of workers who have had an audiogram. Audiometric technicians must pass an approved audiometric technician course and are required to pass a requalification examination every five years.

"biohazardous material"

According to the Laboratory Biosafety Guidelines (3rd Edition, 2004) published by the Public Health Agency of Canada biohazardous materials are classified into the following Risk Groups:

Risk Group 1 (low individual and community risk)
A biological agent that is unlikely to cause disease in healthy workers or animals.

Risk Group 2 ( moderate individual risk, limited community risk)
A pathogen that can cause human or animal disease but, under normal circumstances, is unlikely to be a serious hazard to laboratory workers, the community, livestock or the environment. Laboratory exposures rarely cause infection leading to serious disease; effective treatment and preventive measures are available and the risk of spread is limited. Examples of Risk Group 2 pathogens include the Hepatitis B and C viruses, salmonella, and E. Coli bacteria.

Risk Group 3 (high individual risk, low community risk)
A pathogen that usually causes serious human or animal disease, or which can result in serious economic consequences but does not ordinarily spread by casual contact from one individual to another; antimicrobial or antiparasitic agents can treat the pathogens. Examples of Risk Group 3 pathogens include hantavirus, tuberculosis, human immunodeficiency virus (HIV), and the virus causing Creutzfeldt-Jakob disease (CJD).

Risk Group 4 (high individual risk, high community risk)
A pathogen that usually produces very serious human or animal disease, often untreatable, and may be readily transmitted from one individual to another, or from animal to human or vice-versa directly or indirectly, or by casual contact. Examples of Risk Group 4 pathogens include the hemorrhagic fevers such as Ebola, Marburg and Lassa.

For more information

Laboratory Biosafety Guidelines

"blasting area"

The blasting area defines the area for which the blaster has been assigned direct control.

"blasting machine"

A typical blasting machine produces electric current as a lever is moved through a magnetic coil. The electric current passes through the detonator, exploding the explosive charge. Capacitor-discharge-type blasting machines are also available. These machines store electrical energy and discharge it on demand.


A bootleg is usually recognizable as the remnant of a drill hole where an explosive was detonated. It is treated as though it may still contain explosive materials in its cracks or fissures. Precautions are taken to prevent drilling in or near a bootleg to avoid possible detonation of any remaining explosives.


CANMET sets standards and provides approvals for testing and blasting equipment used in mines.

"combined ventilation system"

A combined ventilation system in a mining operation has two fans, one forcing air towards one side of the face and the other fan helping the air return. This increases the volume of air as well as its turbulence by injecting fresh air to the headings where dust and methane levels could create hazards for workers.

In large underground mining operations, a combination of forcing fans and exhausting fans is used to supply air throughout the mine at a relatively reduced pressure differential. This offers an economical way of ventilating the mine. Also, the reduction in pressure improves equipment performance and is more comfortable for workers.


Any reference to "worker" in the OHS Code is meant to be interpreted in its broadest sense as including all persons working for an employer e.g. "workers", lead hands, foremen, supervisors, managers, directors, etc. Although a supervisor, for example, may be an employer's representative, the supervisor is also a worker.

Three characteristics are used to describe a worker as "competent"

(1) adequately qualified – the worker has some type of qualification, usually earned through a formal education program, training course, etc., or a combination of education and practical experience. With certain exceptions such as professional designations e.g. professional engineer, nurse, physician, etc. or other legal requirement involving qualifications, the employer is responsible for evaluating and deciding if a worker is adequately qualified. The employer should be able to justify the basis on which a worker is considered to be "adequately qualified";

(2) suitably trained – the worker must have training that is appropriate to the tasks, equipment, etc., that will be performed or used. In addition to this training, the worker must receive safety training, the minimum requirements of which are described in section 15 of the OHS Regulation. The employer is responsible for evaluating and deciding if a worker is suitably trained. The employer should be able to justify the basis on which a worker is considered to be "suitably trained"; and

(3) with sufficient experience to safely perform work without supervision or with only a minimal degree of supervision – determining whether a worker has sufficient experience to safely perform work is the employer's responsibility. A worker's qualifications, training and experience are no guarantee that work will be performed safely. The employer should be able to justify the basis on which a worker is considered to have "sufficient experience".

A journeyman's certificate, or an equivalent credential recognized by Alberta Enterprise and Advanced Education, Apprenticeship and Industry Training, is not required under the OHS Act, Regulation and Code to prove the competency of a worker performing the work of a particular compulsory trade.

The absence of an Alberta trade certificate alone is insufficient to consider a worker not competent. The employer is ultimately responsible for ensuring that workers are adequately qualified, suitably trained and have sufficient experience to perform their work safely. Employers need to be aware of OHS and other legislation that applies to their workers.

Subject to certain limitations set by Alberta Enterprise and Advanced Education, Apprenticeship and Industry Training, the following 19 trades are compulsory in Alberta as of the date of publication of this guide:

(a) appliance service technician;
(b) auto body technician;
(c) automotive service technician;
(d) boilermaker;
(e) crane and hoisting equipment operator;
(f) electrician;
(g) electronic technician;
(h) elevator constructor;
(i) gasfitter;
(j) hairstylist;
(k) heavy equipment technician;
(l) ironworker;
(m) motorcycle mechanic;
(n) plumber;
(o) recreational vehicle service technician;
(p) refrigeration and air conditioning mechanic;
(q) sheet metal worker;
(r) steamfitter – pipefitter; and
(s) welder.

For more information

Apprenticeship, trades and occupations information provided by Alberta Enterprise and Advanced Education. Includes the most up-to-date information about compulsory trades in Alberta.

"controlled product"

A controlled product consists of any product, material or substances which, by application of criteria described in Part IV of the Controlled Products Regulation, is included in one or more of the following six classes:

(1) Class A: Compressed Gas
(2) Class B: Flammable and Combustible Material
(3) Class C: Oxidizing Material
(4) Class D: Poisonous and Infectious Material
(5) Class E: Corrosive Material
(6) Class F: Dangerously Reactive Material

Controlled products include a wide range of chemical substances, mixtures and products found at the workplace, as well as various biohazardous and infectious materials.


A decibel, abbreviated as "dB", is the unit of measurement of sound intensity. It is a dimensionless unit calculated using the equation:

The A-weighted sound level, abbreviated as "dBA", is used to measure noise exposure and is obtained from a sound level meter that uses an A-weighting network. The A-weighting network or filter derives its characteristics from certain properties of human hearing. The A-weighting curve is used most frequently since various studies have concluded that it provides a better estimate of the threat to human hearing by a given noise compared to other weighting curves.


A detonator is a relatively small explosive contained in a convenient cylindrical cap that is ignited by a flame (fuse type) or electric current. Ignition of the detonator causes the explosive attached to it to detonate. Electric or non-electric type cap detonators are equipped with a delaying device that allows the sequence of blasts.

"flash point"

Flammable and combustible liquids do not burn. Liquid gasoline for example, does not burn. The vapours given off by the liquid form an ignitable mixture with air. A liquid's flash point is the lowest temperature at which the liquid evaporates quickly enough to produce enough vapours to ignite.

The flash point of gasoline for example, is approximately -40°C; the exact flash point varies with the grade of gasoline. This means that at temperatures as cold as -40°C, gasoline can still evaporate quickly enough to have its vapours create an explosive atmosphere under the right circumstances.

Material Safety Data Sheets (MSDSs) provide information such as a particular liquid's flash point. MSDSs also describe any precautions that need to be taken when handling the liquid.


A gob is an area of an underground mine from which the coal and support pillars have been removed, allowing the roof to cave in.

"hazardous waste"

Examples of hazardous waste include solid and liquid materials such as waste insulation in asbestos removal projects, contents of tailing ponds or sewage systems and products for recycling such as engine oil. A by-product of a production process which is recycled or otherwise used on-site is not a hazardous waste e.g. black liquor in the pulping process. A by-product supplied to a party off-site for use as is (is not subjected to a conversion process such as recycling or recovery) is also not a hazardous waste. The definition of hazardous waste implies an intent to manage or handle the product.

"heavy duty scaffold"

A heavy duty scaffold is capable of supporting both workers and stored materials. The phrase "evenly distributed load" means that all similar parts of the scaffold are "loaded" equally. A concentrated load, depending on its location on the scaffold, may unevenly load one or more parts of the scaffold with resulting structural failure.

A heavy duty scaffold is designed to support loads ranging from 122 kilograms/square metre (25 pounds/square foot) to 367 kilograms/square metre (75 pounds/square foot). Scaffolds intended to exceed the design load of 367 kilograms/square metre must be certified by a professional engineer.

"light duty scaffold"

A light duty scaffold is intended for workers only. Materials other than tools should not be stored on this type of scaffold. The phrase "evenly distributed" means that all similar parts of the scaffold are "loaded" equally up to the maximum limit of 122 kilograms/square metre (25 pounds/square foot). A concentrated load, depending on its location on the scaffold, may unevenly load one or more parts of the scaffold with resulting structural failure.


Explosive magazines are designed and constructed to safely store explosives, detonators and blasting agents. The size, structure and construction details of a magazine are based on the amount and type of explosives stored. Various classes of magazines are designed to address different concerns as indicated in Storage Standards for Industrial Explosives (M81-7/2001E), published by Natural Resources Canada.

"material safety data sheet"

A material safety data sheet (MSDS) is a technical document that provides detailed information about a controlled product that includes

(a) health effects resulting from overexposure to the product,
(b) an evaluation of hazards related to the product's handling, storage or use,
(c) measures to be taken to protect workers at risk of overexposure, and
(d) emergency procedures.

The MSDS may be written, printed or otherwise expressed and must meet the availability, design and content requirements of the Hazardous Products Act and Controlled Products Regulations (CPR). A minimum number of categories of information must be completed and all hazardous ingredients meeting certain criteria must be listed (subject to exemptions granted under the Hazardous Materials Information Review Act). The content categories that must be present are:

(1) Product Information – product identifiers, manufacturer and supplier names, addresses and emergency telephone numbers;

(2) Hazardous Ingredients – a list of ingredients as required under Section 13(a)(i) to (iv) of the Hazardous Products Act;

(3) Physical Data – a variety of parameters, such as physical state, odour, boiling point, etc. that physically characterize the product;

(4) Fire and Explosion Hazard – characteristics of the product that determine the likelihood of its ignition under various conditions and information about how to put out a fire involving the product;

(5) Reactivity Data – information regarding the stability of the chemical and substances with which it may dangerously react;

(6) Toxicological Properties – information about how the product is likely to enter the body and its short-term and long-term health effects due to exposure (information on the ingredients may be provided if there is no testing that has been done for the product);

(7) Preventative Measures – personal protective equipment, handling procedures and engineering controls to be used during product shipping, storage, use and disposal as well as in emergencies such as leaks, spills or other releases;

(8) First Aid Measures – specific first aid measures related to acute effects of overexposure to the product; and

(9) Preparation Information – identification of those responsible for preparing the MSDS and its date of preparation.

The MSDS must include at least nine categories of information with titles similar or the same as those listed above. MSDSs using the International Labour Office (ILO), International Organization for Standardization (ISO), European Economic Community or American National Standards Institute (ANSI) headings are also acceptable, as long as all of the information required by the Controlled Product Regulations (CPR) is present.

For more information

International Format for Material Safety Data Sheets
Bulletin LI011

"mine level"

This definition of level applies to all drivages (tunnels) having a slope within 5 degrees of horizontal. In coal mines, the level is driven generally along the strike, which is perpendicular to the dip of the coal formation. A moderate slope is usually incorporated in the level to help drain any water or other liquid from the level to a sump.

"mine shaft"

In mining operations, any opening in the ground made at an angle of 45 degrees or more from the horizontal is called a shaft. Shafts are generally used for transporting workers and materials. They also accommodate various services such as ventilation, power cables, water lines, communication cables and other utilities.


For a misfire to occur, either the detonation energy was too weak, a cut-off occurred, or the explosion did not propagate through the entire explosive column. A minimum amount of detonation energy is needed for most explosives to explode, and some degree of insensitivity is designed into the explosive as a safety measure to permit its handling.

Misfires must be treated as explosives not yet detonated. The following options may be considered when disposing of a misfire:

(a) a fresh charge with appropriate detonation can be exploded close enough to the misfire to detonate it;

(b) water can be used to wash it out; or

(c) other alternatives prescribed by the explosive's manufacturer.

The area must be controlled to keep people and equipment away until the misfire has been appropriately disposed of.

"occupational exposure limit"

An occupational exposure limit (OEL) is the airborne concentration of substance for which it is believed that nearly all workers may be repeatedly exposed on a day-to-day basis without suffering adverse health effects. The OEL refers to the concentration of the substance to which the worker is exposed, not the concentration of the substance in the workplace.

OELs are based on review of data from experimental animal and human studies and from industrial experience from clinical and epidemiological (comprehensive statistical studies of disease patterns among known groups of people) studies of workers.

While animal and human experimental data are the most useful when determining how the body responds when exposed to single substances or specific mixtures of substances, the studies do not usually represent workplace conditions of exposure. Personal habits such as smoking, drinking alcoholic beverages and using drugs or medications may also affect a worker's health profile. The substances involved in these personal habits may have an additive or synergistic action on exposures at the workplace. Well designed epidemiologic studies can help distinguish between the effects of work-related and non work-related variables.

Exposure limits have been developed by a number of organizations. The OELs are, for the most part, based on Threshold Limit Values (TLVs) developed by the American Conference of Governmental Industrial Hygienists (ACGIH). The basis on which the values are established differs from substance to substance. Protection against health impairment may be a factor for some, reasonable freedom from irritation, narcosis, nuisance or other forms of stress may form the basis for others. Health impairments that are considered include those that reduce life expectancy, compromise physical function of the body, impair the capability for resisting other toxic substances or diseases or adversely affect reproductive capability or the developmental process.

In some cases, Alberta's OELs differ from the ACGIH values. Data associated with exposure to the substances in question was extensively reviewed in these cases. The primary criterion for deviating from the ACGIH values was the health and safety of workers based on available documentation and scientific rationale. The applicability of the rationale to circumstances in Alberta was considered as well i.e. conditions of exposure or special exposure for Alberta workers, safety margin of the ACGIH values, social expectations and technical feasibility of meeting the standards.

Substances for which the OELs differ from the TLVs recommended by ACGIH are listed below:

  • Acetic anhydride, ceiling limit used instead of an 8-hour exposure limit
  • Formaldehyde
  • Hydrogen sulphide, ceiling limit used instead of a 15-minute short term exposure
  • Particulate Not Otherwise Regulated (no ACGIH TLV)
  • Polymethylene polyphenyl isocyanate (no ACGIH TLV)
  • Sulphur (no ACGIH TLV)
  • Sulphuric acid
  • Ozone
  • 1,1,1-Trifluoro-2,2-dichloroethane (no ACGIH TLV)

Inhalable limits for which the numerical value in the 2006 TLV is the same as the current OEL will remain the same, i.e. the total value will be used. This applies to the following substances:

  • Calcium sulphate
  • Captan
  • Diquat
  • EPN
  • Glass fibres
  • Molybdenum
  • Nickel
  • Silicon carbide, nonfibrous

In some cases, inhalable limits were recommended by ACGIH but the TLV documentation supported total limits (which may or may not be the same as the inhalable limits). In these cases, total limits were adopted consistent with the documentation. This applies to the following substances:

  • Flour dust (numerically the same)
  • Natural rubber latex (numerically the same)
  • Borates (half the inhalable limit)

For seven substances, agreement could not be reached on whether or not the ACGIH TLVs should be adopted. These substances will be reviewed further at a later date to determine the most appropriate value to be adopted as the OEL. This applies to the following substances:

  • Asphalt
  • 2,2-dichloropropionic acid
  • Magnesium oxide
  • Methane
  • p,p-oxybis
  • Trichlorophon
  • Wood dust

The OELs presented in Table 2 of Schedule 1 are given in units of ppm (parts per million) and mg/m3 (milligrams per cubic metre). Where the OEL has the units of mg/m3, unless otherwise specified e.g. "respirable", the OEL is the total amount of substance measured in air at the workplace.

"permitted explosive"

This means an explosive was put through a very strict review and laboratory testing schedule by the Chief Inspector of Explosives, Natural Resources Canada. The explosive must meet certain criteria that allow it to be used in hazardous conditions such as gassy coal mines. One of the most important characteristics is the length of time the explosive "flames" during explosion. This duration must be very short for explosives used in coal mines because of the mine's potentially explosive atmosphere.


According to the Pipeline Act, "pipeline" means a pipe used to convey a substance or combination of substances, including installations associated with the pipe, but does not include

(i) a pipe used to convey water other than water used in connection with a facility, scheme or other matter authorized under the Oil and Gas Conservation Act or the Oil Sands Conservation Act,

(ii) a pipe used to convey gas, if the pipe is operated at a maximum pressure of 700 kilopascals or less, and is not used to convey gas in connection with a facility, scheme or other matter authorized under the Oil and Gas Conservation Act or the Oil Sands Conservation Act,

(iii) a pipe used to convey sewage.

"restricted area"

A work area is considered "restricted" if it is likely that its airborne concentration of asbestos, silica, coal dust or lead will exceed the occupational exposure limit (OEL) for that substance.

"restricted space"

For the sake of simplicity, a restricted space can be thought of as a work area in which the only hazard is the difficulty of getting into and out of the space – all other hazards are either non-existent or have been eliminated or controlled as required by Part 2. Restricted spaces are therefore not subject to the permitting, atmospheric testing and tending worker requirements of a confined space. Workers and employers sometimes refer to restricted spaces as non-permitted confined spaces.

Examples of restricted spaces may include building attics, below-ground vaults used for electrical and telecommunications cables, some ventilation system passages and crawlspaces in buildings and the interior inspection spaces of wind turbine blades. Trenches can also often be considered to be restricted spaces if all hazards have been eliminated or controlled prior to workers entering the trench.

Despite being classified as a restricted space, the following requirements of Part 5 Confined Spaces, continue to apply to workers entering a restricted space:

  • a hazard assessment must be performed prior to entry – section 45; 
  • workers assigned duties related to the entry must be trained to recognize hazards and how to perform their duties in a safe and healthy manner – section 46; 
  • general safety requirements involving the use and availability of safety, personal protective, and emergency equipment, as well as a communication system – section 48; 
  • prevention of unauthorized persons entering a restricted space – section 50; 
  • protection of workers from hazards created by traffic in the area of the restricted space – section 51; 
  • workers cannot enter or remain in a restricted space unless an effective rescue can be carried out – section 55; 
  • a competent worker, designated by the employer, must be in communication with the worker(s) inside a restricted space – section 56; and 
  • a safe means of entry and exit must be available to all workers required to work in the restricted space – section 57.

Employers and workers must be mindful that a restricted space can become a confined space if conditions or work practices change.


In a split ventilation circuit, a portion of fresh air from a main intake airway is split away to provide clean, uncontaminated air to a working place. The remainder of the main intake air continues on into the mining operation to meet additional needs. The contaminated air coming from this "split" is then directed back into the main return airway and out of the mine.

"supplier label"

A supplier label is intended for use with a controlled product that is distributed to workplaces in Canada. This label is provided as a condition of sale by the supplier (manufacturer, processor, packager or importer) of a controlled product. The supplier label must meet requirements in the Controlled Product Regulations (CPR) regarding hazard symbols, information categories and label design, format and language.

The supplier is responsible for applying the label to the controlled product unless, under permitted circumstances, the purchaser assumes that responsibility. Content categories required on supplier labels are product identifier, supplier identifier, a statement that an MSDS is available, hazard symbols, risk phrases, precautionary measures and first aid measures. Some products from laboratory supply houses, products that are laboratory samples, and other products sold in very small containers may be allowed to display labels with fewer categories. The information must be displayed in both English and French and must be within a border of the exact design as shown in Schedule III of the CPR. The border requirement does not apply to controlled products from laboratory supply houses packaged in quantities of less than 10 kilograms and intended for use in a laboratory.

"ventilation stopping"

A stopping is used to direct and control ventilation air in a mine. Built to be sturdy and leakproof, stoppings prevent unnecessary leakage of ventilation air. In a gassy mine, stoppings are coated with fire-resistant chemicals to prevent the spread of fire and are made leakproof to prevent recirculation of contaminated air. When a stopping is used to regulate ventilation, the quantity of air flow is controlled by the size of the opening in the stopping. As a barrier, a stopping does not require any openings except where holes are needed to monitor the atmosphere behind the stoppings. Figures 1.1 and 1.2 illustrate a permanent stopping and a stopping used to regulate ventilation.

Figure 1.1 Permanent stopping

Figure 1.2 Stopping for ventilation regulation

"work area"

Subsection 1(n) of the OHS Act defines a work site as a location where a worker is, or is likely to be engaged in any occupation. For workers who work out of their vehicle, any vehicle or mobile equipment used by the worker as part of the job is also considered a work site. The OHS Act clearly indicates that a work site is any location where there is, or is likely to be, a worker doing work as part of their occupation.

A work area is considered to be the place at a work site where a worker actually is or may be during work, or during a work break. At a large warehouse operation for example, the office in which a worker performs work is the worker's work area. The warehouse operation is considered to be the work site.

Situations may arise in which work is performed at two or more locations within a large work site. In such situations, an employer may wish to partition or divide the large work site into two or more smaller work sites. The reasons for doing so may include better access control of persons and vehicles, restricting certain activities to a specific area, and optimizing the type and quantity of first aid supplies, equipment and services required.

Ideally, the areas will be physically separated. For example,

(a) smaller work sites would function independently of one another i.e. there is no work-related interaction between the workers of the smaller work sites;

(b) the perimeter of each of the smaller work sites would be defined by an effective physical barrier such as a fence, wall, etc. This controls vehicular and foot traffic between work sites; and

(c) if two or more employers work at a smaller work site at the same time, then the smaller work site requires its own prime contractor.

For example, a fenced-off construction site within the land occupied by a refinery can be treated as a separate "work site within a work site". A fenced-off construction site within a retail complex can also be treated as a "work site within a work site". By meeting the three conditions listed above, each work site within a work site can be treated as a separate work site for the purposes of complying with the OHS Act, OHS Regulation and OHS Code.

There may also be instances in which work sites can be partitioned administratively e.g. a work area with office functions may be separated by distance or time-of-day activities by a production or packaging work area. When this approach is used, care must be taken to ensure that the "work sites" function independently of one another, that workers understand and respect the administrative limits that separate the sites, and that the potential need for a prime contractor in the partitioned work site is acknowledged.

"work site label"

A work site label is used at the workplace in some circumstances during the storage, handling and use or a controlled product. The employer must provide the work site label for the production and use of a controlled product at the workplace or the transfer of a controlled product received from a supplier to another container at the workplace. The employer may also apply a work site label when an existing supplier label becomes illegible or is accidentally removed and a replacement supplier label is not available. While the definition specifies the type of information that must be present on the label, there is considerable flexibility in the label wording and format. The key considerations are that the label be legible, firmly affixed to the product or container and the wording/format be understood by workers at that workplace.

The product identifier on the work site label must be identical to that found on the MSDS of the corresponding controlled product. Information for safe handling means precautions that the worker must observe to minimize risk of adverse health effects or injury. If an MSDS is available for the controlled product, the work site label must include a statement to that effect. For some products, such as consumer products, an MSDS may not be available, in which case the statement regarding the MSDS is not required on the work site label.

The label must be legible and prominently displayed on the part of the container that is visible under normal conditions of storage and use. If the employer wishes to provide hazard symbols on the work site labels that differ from those required on the WHMIS supplier label, then the symbols used must not result in worker confusion regarding the hazards represented by the product. For example, the colour and number symbols of the National Fire Protection Association (NFPA) apply to hazards created by short term exposure in fire or other emergency situations. They are not meant to apply to hazards associated with long-term exposures that are often found at the workplace. If NFPA symbols were used on a work site label, workers would then need to be instructed in the differences between the NFPA and WHMIS systems.

Work site labels may be revised when new information becomes available. The information must be kept consistent with that provided on the MSDS.


Although the term is not defined in the OHS Code, the term is used throughout the OHS Code and should be understood. Subsection 1(bb) of the OHS Act defines a worker as a person engaged in an occupation. The broad definition is intended to ensure that all persons engaged in hazardous work activities are protected under the OHS Act. It is not necessary for the worker to be paid and therefore volunteers and other unpaid persons are considered to be workers.

The term "occupation" is then defined in the OHS Act as:

every occupation, employment, business, calling or pursuit over which the Legislature has jurisdiction, except

(i) farming and ranching operations specified in the regulations, and

(ii) work in, to or around a private dwelling or any land used in connection with the dwelling that is performed by an occupant or owner who lives in the private dwelling or a household servant of the occupant or owner.

Exempted workers

As a consequence of this definition, the OHS Regulation and OHS Code do not apply to farmers and ranchers, workers working in their private dwellings and domestic workers such as nannies and housekeepers. The OHS Act, OHS Regulation and OHS Code do not apply to students receiving training in an educational setting, regardless of the activities being performed e.g. woodworking class at a grade school, automotive repair course at a technical school, chemistry laboratory course at a university, etc.

Further, the OHS Act, OHS Regulation and OHS Code do not apply to federal government workers, or workers in federally-regulated industries such as banking, telecommunications, television and radio broadcasting, and interprovincial transportation. As an example, construction falls under provincial jurisdiction. Grain elevators are deemed to be for "the general advantage of Canada" and fall under federal jurisdiction. What happens when the grain elevator company hires a construction firm to build a new grain elevator? During the construction phase, construction workers are under provincial jurisdiction because construction falls under provincial jurisdiction.

Once the building is erected and grain personnel move in, the grain elevator is a federally regulated site and the employer must comply with the Canada Labour Code, Part II.

Provided by Human Resources Development Canada (HRDC), Table 1.1 is designed to help employers, workers and regulators determine jurisdiction for the purpose of compliance with occupational health and safety regulations.

For more information

Are Students and Volunteers Workers?
Bulletin LI022

Table 1.1 Summary of industry sectors under federal and provincial jurisdiction

Federal Jurisdiction Provincial Jurisdiction
Passenger/cargo airlines, aircraft maintenance companies, most airside operations such as baggage handlers and refuelers, security services for pre-board screening e.g. Hudson General, PLH Aviation Services and Field Aviation

Airside operations

Air Traffic Control e.g. NavCan
Aircraft component manufacturers, retailers and restaurants at the airport
Sky Chef, Canadian Turbine and United Technologies etc., food kiosks
Oil and Gas Pipelines
Only pipelines that cross provincial or international boundaries are under federal jurisdiction (administered by the National Energy Board)
Pipeline Head Offices and Pipeline Employees and Compressor Stations

Off shore drilling/production

Falls within an aspect of shipping in Canadian waters (National Energy Board)
Pipeline Construction & Maintenance
Construction workers constructing the pipeline
All grain elevators and most feed mills, flour mills, feed warehouses and seed cleaning mills are for the general advantage of Canada. Martin Pet Foods, Landmark Feeds, Masterfeeds, etc.
  • Cargill–feed mill

  • Agricore elevators etc.

Retail service is separated from the elevator operations.
  • Cargill meat processing

  • Agricore fertilizer operations, etc.

Federal Public Service and Government of Canada Crown Corporations
i.e. HRDC, Labour, Canada Post or CMHC etc.
Provincial Public Service
A railway, canal, telegraph or other work or undertaking connecting any province with any other province, or extending beyond the limits of a province  
CN, CP Rail, etc.
ProCar, PDS Railcar Service, Central Western Railway, Stettler Short Line, etc.
Road Transport
Interprovincial trucking companies (common carriers) and their facilities (warehouse, maintenance garages). This includes bus/courier/moving companies and oilfield haulers that are common carriers or interprovincial trucking.
Canadian Freightways, Tri-Line, SLH Transport, Jo-Ann Trucking (oilfield hauler), etc.
Safeway – (Safeway and The Brick haul exclusively their own product unlike Tri-Line) etc.
Buses, Couriers
Greyhound, Brewster, UPS, Purolator, etc.
Buses, Couriers
School buses and city buses, local couriers, bicycle couriers, etc.
All chartered banks – Bank of Canada, HSBC, Bank of Montreal, etc.
Trust and Credit Union operations
All trust companies and credit unions – Canada Trust, Alberta Treasury Branch, Calgary First, etc.
Telephone companies and most national paging companies – Telus, AT&T, etc.
Companies selling cellular devices e.g. TAC Mobility, etc.
Broadcasting – jurisdiction determined respecting hertzian waves
All radio, television and cable operations – Shaw, City Cable, WIC Communications, etc.
First Nations
Band employees and industries which benefit the band. When in doubt, call HRDC
First Nations
Industries which do not benefit the band itself
All materials other than uranium

Consult the Federal Government Office,
Human Resources and Social Development Canada
To verify correct jurisdiction