Written by Abimbola Badejo, Staff Writer

At the recent Partners in Prevention 2019 Health and Safety Conference, Ontario, Canada; organized by Workplace Safety and Prevention Services (WSPS) Ontario, Canada, Dave Gardner of Pinchin Ltd. delivered a presentation on Demystifying Occupational Hygiene. Mr. Gardner is Senior Occupational Hygiene and Safety Consultant with Pinchin Ltd. Below is a summary of his presentation.


Occupational hygiene has been defined by the United States Department of Labour Occupational Safety and Health Administration as “that science and art devoted to the anticipation, recognition, evaluation, and control of those environmental factors or stresses arising in or from the workplace, which may cause sickness, impaired health and well-being, or significant discomfort among workers or among the citizens of the community.1. Simply put, the goal of Occupational hygiene is to ensure the safety and protection of a worker at his or her workplace provided the worker follows a set of guidelines that have been put in place to safeguard his/her health and safety. While we’re on the topic of health within the workplace, it then comes as no surprise to find that companies are deciding to get in touch with a cleaning company who provide commercial cleaning services, contractor London, for example, in the hopes of getting their workplace clean and up to a good standard that won’t harm the health of the staff. This is important for any company to think about, especially as health should be a priority.

Occupational hygiene concerns fall under the remit of human resources departments, who can use HR Software to ensure that appropriate monitoring, reporting, and training opportunities are put into place.

Typical occupational hygiene principles include written standards, procedures and practices; workers training as part of a knowledge management program; logical thinking on the part of the creator; a combination of actions with words learned from the written standards; and total compliance with associated regulations.


An Occupational Hygiene program is of great importance as its negligence leads to occupational injuries and diseases. Occupational diseases are considered more significant due to factors associated with it; which include

  • Diseases caused by exposure to either chemical, physical or biological agents at the workplace
  • Sources such as exposure to airborne asbestos particles, confined spaces, noise, construction projects, etc.
  • Categories namely Long Latency Illness, Noise Induced Hearing Loss (NIHL), Chronic Exposure and effects and Acute Exposure and effects
  • Observable effects which are not seen until after a long duration of exposure
  • 75% of fatalities in diseases, attributed to occupational origins

The Ontario Workplace Safety and Insurance Board (WSIB) reported that approximately 130 thousand claims were filed, and about $940 million benefit costs were released, between 2008 and 2017. Occupational diseases with long latency are mostly serious and these account for only three percent of the occupational diseases with benefits.

Based on these factors (and those not mentioned), reviews have been made by the Human Resources and Skills Development Canada (HRSDC) and Labour Canada. These reviews include updates made to the Occupational Exposure Limits (OEL) of chemicals, training workers on the safe usage of materials and the equipment at the workplace, thorough knowledge of the materials and substances used at the workplace, compulsory and proper use of Personal Protective Equipment (PPE), alertness of workers to the state of their own health and compulsory medical check-ups in relation to workplace risk assessment.


A survey made by the Center for Construction Research and Training regarding occupational diseases in the construction industry reported that the workers in this industry are:

  • twice as likely to have chronic obstructive lung diseases, five times more likely to have lung cancer, thirty-three times more likely to have asbestosis
  • inclined to suffer a 50% increase in Lung Cancer related deaths
  • predisposed to noise induced hearing loss (NIHL) (50% of workers)
  • susceptible to elevated levels of lead in their blood (17% of workers)
  • exposed to the allowable 8-hour exposure limit for Manganese during welding processes. This was observed with workers involved in boiler making (75%), iron-working (15%) and pipe-fitting (7%). All welders much wear appropriate clothing and helmets when welding to keep them safe. There are suitable welding helmets on Helmethunt.com if current helmets need replacing. If you work in the construction industry and are looking to reduce the health risks associated with welding, then it is in your best interest to invest in the latest welding equipment. For more information, check out this guide to an ideal welder for starters.

In addition, a nationwide report has disclosed that 40% of WSIB costs are for construction occupational diseases, more construction workers die from a combination of occupational diseases and traumatic injuries and that 2 to 6 construction workers are more likely to develop occupational lung disease and NIHL.

As observed, most of the occupationally related diseases can be prevented by simple tasks such as hand-washing, proper use of PPE and correct compliance to defined regulations.


To ensure the protection of workers in various Canadian industries, regulations and guidelines have been put in place; some of which require compliance by either the employee or the employer. The legislations and related codes/standards guiding occupational hygiene in workplaces include:

Some of the provided regulations and guidelines are specific while others are general in application. The key to correct interpretation is to apply the correct regulation to the right workplace situation.

An example of a proper legislation application: Silica is an inert substance and an irreplaceable material in most products and buildings in the world today. As the second most abundant mineral on the planet, silica is used in numerous ways. Getting the substance to the usable state requires processing, which exposes the worker to the respirable crystalline form. The regulation (O. Reg 490/09), listing silica as a designated substance, does not apply to the silica infused products but to the respirable fractions which the processing worker is exposed to. The regulation specifies an occupational exposure limit (OEL) for respirable crystalline silica as 0.05 mg/m3 of air (cristobalite silica) and 0.1 mg/m3 of air (quartz and tripoli silica) for an 8-hour/day or 40-hour weekly exposure. This regulation, however, does not apply to the employer or some other workers on a construction project; but the employer’s responsibility will be to protect the worker’s health in compliance to section 25 (2)(h) of the OHSA, requiring employers to take every reasonable precaution in the circumstances to protect a worker.


Before initiating an occupational hygiene program, a clearer understanding of basic terms is ideal.

Industrial Hygiene: this is an exercise devoted to the anticipation, recognition, evaluation, and control of those environmental stresses arising from the workplace, which may cause the impairment of a worker’s health.

Toxicology: the study of how chemical, physical and biological agents adversely affect biological systems. The adverse effects include irritation, sensitization, organ failure, diseases or cancer.

Disease, dose and exposure: Disease / response is caused by an agent dosage. Dosage is measured in relation to the exposure of the worker to an agent. Mathematically, exposure is calculated as the agent concentration multiplied by duration of exposure (concentration x time). Therefore, sampling surveys are simply estimating the exposure of the worker to a specific concentration of the agent. Exposure routes may be through inhalation, ingestion, contact or skin absorption.

Threshold Limit Values (TLV): TLVs are general concentration limit values for specific chemicals, to which a healthy adult worker can be exposed. However, TLVs does not adequately protect all workers as their susceptibility levels to various chemicals are unique to them. TLVs are used by regulators as guidelines or recommendations to assist in the control of potential workplace hazards.

Time-Weighted Average (TLV-TWA): TWA concentration for a conventional 8-hour/day or 40-hour/week , to which a worker may be repeatedly exposed.

Short-Term Exposure Limit (TLV-STEL): This is a 15-minute TWA exposure that should not be exceeded.

Ceiling (TLV-C): This is a concentration that must not be exceeded during any part of working exposure

Air Monitoring: This is a process of sampling the air in the workplace, on a regular basis. The monitoring may be qualitative (risk assessments, hygiene walkthroughs and training) or quantitative (air, noise and wipe sampling) in perspective.


The first focus of an occupational hygiene program is to conduct a risk assessment of the workplace processes. A risk assessment shows that 20% of the activities or tasks carried out, leads to 80% of risks. Carrying out a risk assessment, focuses on the adverse effects of a hazardous agent and the associated level of risk if a worker is exposed to it. Approaches to risk assessment include Critical Tasks Analysis (where stepwise task and risk inventories are made with the focus on worker’s safety), Process Safety (where the focus is on the process, controlling the risk to keep the worker safe) or a combination of both approaches. Risk assessment, therefore, is done as thus:

  1. Making a list of the agents the worker is exposed to,
  2. Identifying the routes of entry,
  3. Identifying a relative risk level (low, medium or high),
  4. Documenting the control in place and its effectiveness.

Table 1. Requirements of a Hazard Reviewer. Scores are used to dictate the skill level required to assess and develop control strategies.

Minimum Requirements
<10 Low to Medium low Any trained employee
>10 to <20 Medium Health and Safety Department or a contracted Health and Safety Consultant
20 & above High Certified Health and Safety Professional or Industrial Hygienist (CRSP, CSP, CIH, ROH)


A preliminary survey is initially conducted using simple and common tools such as human senses (sight, taste, hear, smell, taste and gut-feelings), video camera, photo camera, tape measure and a notebook. Optional tools include velometer and smoke tubes.

Next, all knowledge and processes related to the hazardous agents are sought out using the central dogma of risk assessment (Recognition, Evaluation and Control).

The sampling itself should be done using standardized and validated methods (NIOSH, EPA, ASTM, etc.).

The extent of sampling should be determined, whether personal (breathing zone) samples or area samples.

Next, the duration of sampling should be determined, which could be a whole day, full-shift, partial shift, single samples, sequential samples, grab or composite samples.

The worker to be sampled should be with the worker with the highest exposure potential or a group of workers with similar exposure due to the similarity of their tasks at the workplace.

The amount of samples taken should also be determined.

The time of sampling should be determined (day or night shift, winter or summer season, etc.)

Documentation should be made at every sampling point; and this should include start and stop times, environmental conditions, chronological log of work tasks, quantified conditions during production, duration of shifts and break periods, use of PPE, engineering controls, housekeeping habits and the state of workplace ventilation.


Occupational hygiene programs are made with several guidelines governing it. According to the province of Ontario, all control programs must provide engineering controls, work practices and hygiene facilities to control a workers exposure to a designated substance; methods and procedure should be put in place to monitor airborne concentrations of designated substances and measure workers exposure to the same; training programs should be organized for supervisors and workers on the health effects of the designated substance and the respective controls required. A typical Occupational Hygiene program, therefore, should include the following:

  • Version history
  • Purpose / objectives
  • Scope and application
  • Distribution
  • Definitions and abbreviations
  • Roles, responsibilities and accountabilities
  • Program management (Resources, commitment and program coordinator)
  • Risk assessments
  • Exposure monitoring plans
  • Occupational hygiene surveys (sampling strategy development, analytical services, documentation and reporting )
  • Occupational hygiene controls
  • Training
  • Related document / appendices
  • Quality assurance
  • Maintenance of standard operating practices (SOPs)
  • Annual summary report.


An occupational hygiene program is an important component of workplace management. This ensures the protection of workers’ health, which leads to better and greater productivity at the workplace. The foundation of occupational hygiene programs is to understand the principles that govern the program and knowing how to apply the principles to various situations at the workplace. Proper application and effective controls will assist in achieving the goal of establishing a safe environment for workers to operate.


  1. https://www.osha.gov/dte/library/industrial_hygiene/industrial_hygiene.pdf