This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply the law based on the facts in the workplace.


To assist employers, workers, and other workplace parties in developing and implementing an airborne hazard management program (AHMP) as required by Section 182 of Regulation 854 – Mines and Mining Plants made under the Occupational Health and Safety Act (OHSA).


The objectives of this guide are to:

  • provide guidance and information about developing an airborne hazard management program in mines and mining plants
  • raise awareness of recognizing, assessing, and controlling airborne hazards and their associated risks to health
  • prevent occupational diseases caused by airborne related hazards

Legal requirements

Regulation 854 sets out the following requirements for controlling airborne hazards in mines and mining plants:

  • Section 182 (airborne hazard management program)
  • Section 183 (diesel-powered equipment used in underground mines)
  • Section 183.1(airflow where diesel-powered equipment is operated in underground mines)
  • Section 183.2 (worker exposure to elemental carbon from diesel emissions in underground mines)
  • Sections 183.3 and 183.4 (testing of diesel-powered equipment in underground mines)
  • Section 184 (exhaust from engines installed in buildings on surface)
  • Section 252 (ventilation systems in mines and mining plants)
  • Section 254 (heat stress and cold stress procedures)
  • Section 255 (unventilated areas of underground mines)
  • Section 261 (ventilation of battery-charging stations)
  • Section 266 (removing dust and other airborne hazards)
  • Section 267 (surveys of potentially hazardous minor elements from feed streams and concentrations in mining plants)
  • Section 268 (records of potentially hazardous chemical reagents used in mining plants)
  • Section 269 (equipment to detect physical and chemical agents in mining plants)

Sections 5.1 to 5.3 of Regulation 854 requires employers to conduct an overall risk assessment of the workplace. Employers must develop and maintain measures to eliminate, where practicable, or control, where elimination is impracticable, the hazards and potential hazards identified in the risk assessment.

Regulation 833 - Control of Exposure to Biological or Chemical Agents sets out the prescribed limits for worker exposure to airborne contaminants.

Regulation 490 - Designated Substances sets out the prescribed requirements for persons working with the following designates substances:

  • acrylonitrile
  • arsenic
  • asbestos
  • benzene
  • coke oven emissions
  • ethylene oxide
  • isocyanates
  • lead
  • mercury
  • silica
  • vinyl chloride

Regulation 632- Confined Spaces sets out the requirements for managing airborne hazards when working in confined spaces.

Regulation 860- Workplace Hazardous Materials Information System (WHMIS) sets out the requirements for managing hazardous products in the workplace.


An airborne hazard is a chemical, biological, or radiological agent that can occur in either a gaseous form (as a gas or vapour) or as an aerosol (dust, mist, or fume) and has the potential to cause harm through occupational exposure.

Short-term exposure may cause acute health effects or long-term exposure may cause chronic health effects or occupational illness. There are occupational exposure limits (OELs) set out in the OHSA regulations that restrict the amount of airborne concentration and the length of time a worker can be exposed to hazardous biological or chemical agents. While workplaces must comply with the current OELs, workplaces should also strive to eliminate or reduce worker exposures to hazardous airborne substances to as low as reasonably achievable.

Airborne hazards can be generated through a variety of underground and surface activities, including but not limited to:

  • crushing
  • grinding
  • blasting
  • welding
  • spraying
  • atomizing
  • mixing
  • combusting
  • transporting

Common airborne hazards in Ontario mines and their associated surface plants include, but are not limited to:

  • diesel emissions, including particulate matter and nitrogen dioxide (for example diesel- powered equipment)
  • silica and dust (for example sources include roadways, mucking, blasting and shotcrete, crushing and conveying)
  • blast gases
  • strata (for example inherent gases), including methane and hydrogen sulfide
  • radon
  • carbon monoxide and carbon dioxide (for example from mine heating plants and diesel equipment)
  • ammonia (for example blasting and back fill)
  • inhalable copper and nickel dust (for example mines, mills, and smelters)
  • isocyanates (for example from spray on liners, sealing foam, and ground support resin)
  • asbestos (for example particularly in ore or insulation materials on site)
  • cyanide (for example from some types of gold refining processes)
  • refrigerants (for example ammonia or sulfur dioxide from cooling plants)
  • chromium (for example in cement, welding, and custom feeds at smelters)
  • arsenic, lead, cadmium (for example impurity in metal ores, lead in fire assay flux)
  • hydrogen sulfide, sodium sulphate (for example milling process and the production of sulfur and sulfuric acid)
  • hydrochloric acid, sulfur dioxide, dioxins, furans, heavy metals, and possibly cyanide from fires involving batteries in electric vehicles

Workers in mines and mining plants can potentially be exposed to airborne contaminants that can cause occupational diseases including lung diseases (for example silicosis) or various forms of cancer. Workplaces need to be aware of the serious nature of airborne contaminants and put programs in place to protect worker health and safety.

Airborne hazard management program (AHMP)

The requirement to have an AHMP applies to employers at all mines and mining plants that fall under Regulation 854. It is important for employers to consider that airborne hazards can occur during both planned and unplanned work as well as under upset conditions (e.g., equipment failures, unexpected events or fires). The airborne hazard management program must be developed and maintained in consultation with the joint health and safety committee (JHSC) or health and safety representative (HSR), if any, and is intended to apply to all routine and non- routine work.

Mine contractors at a mine or mining plant can either develop their own AHMP to protect their workers or they may work with the employer of the mine or mining plant to use some or all the operation’s existing program. To ensure all workers are protected, good practice dictates that if the contractor’s program is different, then it should be reviewed prior to work beginning.

The AHMP must set out the airborne hazards and potential airborne hazards that have been identified and assessed as part the workplace risk assessment. An airborne hazard management program must also include the following elements:

  • measures and procedures required to effectively eliminate or control airborne hazards and potential airborne hazards
  • identified persons responsible for implementing the program
  • identified training required for the responsible persons
  • sampling and testing frequencies, locations, strategies and methodologies for assessing worker exposure and identifying air contaminant sources
  • measures and procedures to maintain, monitor and measure the effectiveness and performance of control systems

Some of these program elements may be addressed in other existing programs or systems that are related to airborne hazards that are required under OHSA and the regulations, such as control programs for designated substances and respiratory protection programs. If so, workplaces can cross-reference, mention, or incorporate those existing programs or systems in their AHMP to avoid duplication and utilize internal resources more efficiently.

Measures to control airborne hazards

An employer should consider the hierarchy of controls (HOC) to protect workers from exposure. When controlling airborne hazards, it can be useful to apply the HOC using the source, pathway, and receptor model.

  1. source: creation of contaminants
  2. pathway: contaminants in the work environment
  3. receptor: worker exposure to contaminants

Controlling airborne hazards at the source provides the greatest mitigation factor because it helps to reduce or eliminate the contaminants from entering the work environment. Controlling airborne hazards along the pathway helps to reduce the concentration, duration, and likelihood of worker exposure to contaminants. Lastly, controlling exposure at the receptor is ensuring that workers have the appropriate personal protective equipment available and are trained in its use.

For example, to reduce a worker’s exposure to diesel exhaust, emissions should be:

  1. Controlled before the source (such as, alternative powered engines or higher tier diesel engines).
  2. Ventilation should be increased along the pathway to dilute the concentration of engine exhaust.
  3. As a last resort, workers must be provided respiratory personal protective equipment where exposure levels may exceed occupational exposure limits (OEL).

When using the HOC, use higher order, more effective, controls for hazards with higher risks (for example, carcinogens). Consider the use of proactive controls which look to prevent the hazard from occurring versus reactive controls which look to manage the consequences of a hazard that are present in the workplace.

The following are explanations and examples on how to use the HOC in order of effectiveness.


Elimination of airborne hazards is the best way to protect the health of workers. Any proposed elimination strategy should be carefully examined to avoid the potential of creating other hazards or negative effects in the workplace. An example of elimination is utilizing new technology to fundamentally alter the operational process, such as using battery electric vehicles instead of diesel-powered equipment underground or not using custom mill feed sources that contain hazardous chemicals like beryllium.

Substitution or reduction

Substitution or reduction may be appropriate where equipment or work processes associated with high-risk hazards can be replaced with alternative equipment or processes that reduce the hazards. An example of a substitution control could include switching the type of explosives used in a blast from ammonium-nitrate and fuel oil (ANFO) to emulsion to reduce the amount of blasting contaminants produced.

Engineering controls

Engineering controls can also be effective in controlling airborne hazards. Examples that can be part of an airborne hazard management program include dust suppression systems, such as:

  • water sprays
  • general ventilation systems
  • local exhaust ventilation systems (LEV)

An LEV has four components:

  • a collecting hood
  • ducting
  • an air mover (fan)
  • an air cleaner

Some industry examples may include:

  • smoke eaters for welding
  • down draft tables in machines shops
  • bag houses in mining plants

Isolation of workers

Isolation of workers from the hazard can be an effective control if the workers are safely isolated from the airborne hazards. Examples of isolation include:

  • operator booths (rock breaker and crusher)
  • central control rooms
  • remote or automatic equipment control (removing the worker from the hazard)
  • central blast systems

Administrative controls

Administrative controls are those that rely on the skills, knowledge, experience and actions of people. Examples of work practices and administrative controls may include:

  • diesel control boards
  • blast clearing procedures
  • housekeeping and cleaning programs, such as industrial vacuuming
  • shift lengths/shift rotations
  • safety data sheet reviews
  • type of equipment or materials purchased

Other administrative controls that workers and employers can use to control airborne hazards include:

  • standard operating procedures and maintenance practices
  • engineering reports
  • guidelines for installation
  • original equipment manufacturer (OEM) instructions

Personal protective equipment (PPE)

Personal protective equipment (PPE), as a last resort, can be used to protect workers from airborne hazards. PPE must be appropriate and suitable for the intended purpose and the concentration of contaminants that are likely to be encountered. Respiratory protection and other PPE can help protect workers’ health when they are exposed to certain hazards.

Sampling, testing and monitoring

Industrial hygiene exposure assessments can identify airborne hazards in the workplace and can help in the selection of appropriate control measure(s) to effectively control the hazards. Industrial hygiene exposure assessments include sampling, testing and monitoring.


Sampling is the process of:

  1. Collecting the constituents within a quantity of air over a period of time.
  2. Analyzing the sample to determine the quantity of the different materials, including contaminants within.
  3. Using the measurement to calculate the quantity of contaminants in the volume of air, otherwise known as the concentration.

A sample, for the purpose of this guideline, can be simply interpreted as a measurement of the concentration of a certain agent (contaminant). Some operations use the word “testing” interchangeable with “sampling.” However, for the purpose of this guideline “sampling” will be utilized to represent the process to determine an airborne concentration of a specific agent.


A test method applies to analysis and describes the precision attributable to measurements for a single filter. Multiple air samples are usually necessary to characterize airborne concentrations across time and space. The number of samples necessary for this purpose is proportional to the variation in measurement across samples, which may be greater than the variation in a measurement for a single sample. Typically, this would be a calibration process conducted within a laboratory’s quality assurance process.


Monitoring is like sampling, but it is typically done on a continuous fashion in real time. These processes rely on electronic measuring devices that must be calibrated and maintained according to the OEM specifications.

Sampling processes

Samples should be taken as consistently as possible throughout the calendar year on a schedule developed by a competent person trained in occupational hygiene and in consultation with the JHSC or HSR, if any. This schedule should account for:

  • seasonal variability
  • changes in temperature
  • changes to processes and ventilation

If there is considerable variation in these conditions, sampling plans should be conducted on different days to reflect the varying exposure conditions. If a minimum number of samples are to be collected or if the sampling process is used to evaluate a specific problem area, then sampling should address measuring exposures during peak activities or upset conditions to identify the worst case. This would include, for example, sampling crushing plant operators while the crushing plant is operating.

When problem areas are identified, the sampling strategy and existing controls must be reevaluated and prioritized. Industrial hygiene testing and sampling can identify airborne hazards in the workplace and can help in the selection of appropriate control measure(s) to eliminate or effectively control the hazards. Monitoring systems can be installed and utilized to determine the effectiveness of existing controls, and whether additional controls are needed to effectively manage airborne hazards.

In general, personal sampling is preferred over area sampling, and should be utilized wherever possible to assess worker exposure. Employers can use a strategy that is a balance of both personal and area sampling to obtain accurate data representative of worker exposure and workplace conditions. The use of personal exposure monitoring is preferential when evaluating OELs, however there could be situations where only area sampling is available.

A combination of full shift sampling and task-based personal sampling can be used to accurately assess worker exposure and the effectiveness of controls to assist workplace parties in determining the occupational exposure.

Sampling strategies

Effective sampling strategies help ensure there is adequate data collected that can be used to determine and understand the risk of exposure that workers encounter. These strategies should be based on the known airborne hazards in the workplace and their sources to ensure effective control measures are in place.

A thorough characterization and understanding of the workplace, workforce and environmental agents are needed before exposures can be assessed. At a minimum, the following should be evaluated:

  • the chemical, physical and biological agents in the workplace
  • the potential health effects associated with excessive exposure to these agents
  • established occupational exposure limits (OELs)
  • how the workforce is organized and staffed, including routine and non-routine assignments, schedules, and tasks
  • the potential significant sources of exposure(s) to the agent(s)
  • processes and operations
  • work practices and tasks
  • controls that are in place, how they are used, and their perceived effectiveness

Following a review of the information gathered in the basic characterization stage, workers can be assigned to groups by looking for employees who:

  • work in similar processes
  • perform similar jobs or tasks
  • work with similar materials
  • perform work in a similar manner, including the use of control measures

The groupings are referred to as similar exposure groups (SEGs) and serve as the basis for exposure assessments.

When developing a strategy for exposure sampling, when similar levels of worker exposure are encountered, consider these factors:

  • number of workers exposed
  • frequency and duration of exposure
  • the health effects of the agent

Best practice documents in industrial hygiene exposure assessment are a good source of information to determine the number of samples required and the frequency of sampling periods.

Sampling programs should ensure that enough samples are taken to account for the potential sample failure. Sampling programs should also have a process to resample failed samples as may be required.

Workplaces should ensure that records of occupational hygiene monitoring are maintained in accordance with legislated requirements. Current and historical monitoring records can be used to:

  • establishing baseline exposure profiles
  • conducting statistical analysis
  • performing periodic sampling

Sampling requirements should be prioritized based on risk of exposure. Examples of best practice resources include:

  • American Industrial Hygiene Association (AIHA) A Strategy for Assessing and Managing Occupational Exposures
  • National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods

All affected workplace parties and the JHSC or HSR, if any, must be informed of:

  • the findings from any monitoring and assessment conducted in the workplace
  • additional controls that are implemented because of exposures to workers

In workplace areas with stable exposure results, reduced sample frequency can be considered.

Industrial hygiene sampling programs should be developed and implemented in consultation with an industrial hygiene professional (Certified Industrial Hygienist or Registered Occupational Hygienist) and must include the JHSC or HSR, if any.

Program implementation and responsibilities

Workplace parties responsible for implementing, overseeing, and coordinating the program must have the appropriate competencies to ensure the effectiveness of the program. The person overseeing the program may be an employee of the workplace or a third party contracted by the employer.

The responsible workplace parties should have qualifications, such as a certificate, diploma, or degree in occupational or industrial hygiene from a post-secondary institution, career college or similar entity and have specific training in:

  • introduction to physiology and toxicology
  • industrial hygiene standards
  • air sampling theory and practice
  • sampling methodologies and interpretation of results

The AHMP may require the additional support of subject matter experts who have the skill sets and experience needed to help determine:

  • the locations of the samples
  • the frequency of testing
  • the number of samples to be taken

These subject-matter experts may be either employees at the workplace or external consultants that have experience and knowledge of workplace airborne hazards, for example:

  • occupational/industrial hygienists
  • ventilation engineers or technicians
  • safety specialists

Laboratories carrying out analysis of samples should be able to demonstrate technical proficiency and quality assurance in the required testing, for example by laboratory accreditation such as:

  • Industrial Hygiene Laboratory Accreditation Program (IHLAP) operated by the American Industrial Hygiene Association Laboratory Accreditation Programs (AIHA-LAP)
  • Occupational Hygiene Laboratory Accreditation program operated by the Canadian Association for Laboratory Accreditation Inc.(CALA)
  • the ISO/IEC 17025 standard for testing and calibration laboratories


In general, everyone, including contractors, who may be exposed to airborne contaminants in the workplace, needs to be provided with information and training about the properties and health effects of the contaminants to which they could be exposed.

Workers and supervisors also need to be aware of:

  • the controls that are in place to prevent harm
  • their responsibilities for implementing and maintaining the controls
  • their role in the airborne hazard management program

The Joint Health and Safety Committee (JHSC) and health and safety representatives (HSR) must also understand their roles in the program and where information can be obtained.

A basic workforce education and training program should include:

  • requirement for an AHMP and the purpose of the program
  • general information related to the exposure to airborne hazards
  • potential health effects of those airborne hazards present within the workplace (site specific)
  • sources of exposure, factors that influence exposure levels, and high exposure situations
  • occupational exposure limits specific to the hazards in the workplace
  • how exposure levels will be measured at the mine or mining plant
  • the controls that are in place to minimize exposure, how they function and what must be done if problems are encountered
  • detail of procedures and expectations of the airborne hazard controls
  • training in WHMIS and Safety Data Sheets
  • review of existing designated substance control programs
  • review historic occupational hygiene air sampling results

The AHMP program should recognize that job-specific training may be needed depending on a worker’s role in the workplace and their risk of exposure. Some workers based on their job tasks may have higher risk of exposure than others and may need additional awareness about airborne hazards that pertain to their specific work, such as mine production workers or mill operators.

As changes to the program are made through the annual review or the introduction of new controls, workers may require additional training, information and instruction. Documentation and records of all training must be retained and be available for review.

Joint health and safety committee consultation

Subsection 182(1) of Regulation 854 requires employers to develop and maintain a written airborne hazard management program in consultation with the joint health and safety committee or health and safety representative.

Where the OHSA or its regulations require that an action be taken in consultation with another party — including but not limited to the joint health and safety committee or health or safety representative — the Ministry of Labour, Immigration, Training and Skills Development expects that the employer will engage in a meaningful interaction with the committee or representative, including, but not limited to dialogue, discussion and providing all relevant information.

Consultation is not simply informing the joint health and safety committee or health and safety representative that the employer intends to act. There should be a genuine opportunity for the committee or representative to comment, and those comments should be received and considered in good faith. This includes considering any feedback and responses from the committee or representative before acting (for example, implementing a plan or program) and responding to any recommendation arising out of the consultation.

In addition to consulting with the joint health and safety committee or health and safety representative, if any, an employer must provide them with a written copy of the program and keep a copy readily available at the mine or mining plant.

It is important that the JHSC or HSR, if any, is aware of the entire process involved in developing and maintaining an effective airborne hazard management program and understands that other workplace parties can also have roles within this process.

Program review

Section 182 requires that the airborne hazard management program must be reviewed as often as necessary and at least annually. This review is necessary to ensure that new airborne hazards, or existing hazards that may have changed during the intervening period, are addressed, and that the program and its controls continue to remain effective. The review should be conducted by a person or persons competent in the practice of occupational or industrial hygiene and in consultation with the joint health and safety committee or health and safety representative, if any.

The AHMP must be reviewed as soon as possible if there has been a change to a mining process, work or method or ventilation system that results in new airborne hazards or a change to existing airborne hazards; or the biological or chemical substances in the workplace that affect airborne hazards.

The types of changes likely to impact the AHMP could include:

Mining processes and work methods

Changes to:

  • mining method (for example, blasthole, longhole, cut and fill, etc.)
  • back fill methods and products
  • motive power (diesel, electric, battery)
  • process or product in a mine or mining plant (for example, crushing, grinding, separation), and/or during smelting or refining

Material changes

Composition of ore, waste rock or feed stream (for example, presence of asbestos or silica).

Ventilation systems

  • Reversing direction or the result from a breakthrough in mine ventilation system (new raise, major new development)
  • volume changes
  • adding or removing hoods on local exhaust systems
  • altering flow volume in local exhaust or general dilution ventilation
  • addition or removal of cooling towers, refrigeration plants, etc.

New or changed chemical substances

Changes to:

  • blasting methods/agents
  • ground support resins
  • shotcrete
  • fill material or additive
  • fuels
  • ore supplies
  • milling reagents
  • smelting or refining reagents
  • custom feeds for smelters or refineries

Reported injuries or illnesses

Employers should also consider a review of their AHMP in the event of WSIB claims or other reports by a current or retired worker concerning an occupational illness or poisoning that may be related to exposure to airborne hazards from the workplace.

Legislative changes

Changes in legislation or regulation would require a review if occupational exposure limits for airborne hazards in a workplace change or if other amendments affect parts of the airborne hazard management program.

Not all changes may require a review

Minor changes such as one that does not alter or affect a substance’s Workplace Hazardous Materials Information System’s (WHMIS) classification or a product’s hazardous ingredients, such as switching suppliers or where only the product name changes, may not generally prompt the need for a review of the program. Another example may include seasonal ventilation changes where shop doors and windows are left open in the summer if these conditions are considered as part of the AHMP.

Changes to industry standards

Revisions to the AHMP may be necessary as a result of changes to industry standards published by the Canadian Standards Association and other national or international organizations. Standards are periodically reviewed, and any resulting revisions could affect a mine or mining plant’s airborne hazard management program.