Occupational Illness

General Resources:

Exposure Categories

Exposure to hazards in the workplace can result from many sources including: 

An icon showing several plumes (clouds) of smoke

Wildfire Smoke

Icon depicting the concept of sound / noise waves


Icon depicting the concept of diesel exhaust

Diesel Exhaust

Icon depicting the concept of asbestos with fine particles sandwiched between layers of material


Icon depicting the concept of silica dust using a diamond-like structure


Icon depicting the concept of temperature using a thermometer


Icon depicting some fume/gas waves floating up through the air from a single source

Vapours / Gases

Icon depicting the concept of allergens and irritants

Allergens / Irritants

Icon depicting mould (mold) spores

Mould (Mold)

Icon of a chemical drum overlayed with two smaller chemical containers


Icon showing dust particles

Metal, Dust & Fumes

These hazards are outlined in greater detail below and resources are provided where available.


Smoke from wildfires is a definite concern for both indoor and outdoors workers.
The biggest health concern from smoke is from fine particles (PM2.5) that can irritate or harm eyes and your respiratory system.
There are several things you can do to minimize your risk while at work.
Your employer also has responsibility to do everything "reasonable" to protect you.


We are working on developing more resources related to the topic of wildfire Smoke.
Bookmark this page so you can check back here often or follow us on social media to stay up-to-date.


Wildfire Smoke – A Definite Concern for All [Ontario] Workers

A 4-page infographic covering the signs and symptoms of wildfire smoke exposure as well as tips for prevention when working indoors and outdoors.

A snapshot of the OHCOW Wildfire Smoke infographic


Noise causes noise-induced hearing loss (NIHL). NIHL is the most common work-related illness in Ontario. A workplace can be too loud if people have to raise their voices to be heard, if they have a ringing in their ear at the end of the day, or even if you notice the car radio is louder the next morning. But quiet workplaces can be a problem if there are infrequent but very loud impact noises, too.

Go to NOISE page



Noise-induced Hearing Loss (NIHL) Audiogram Calculation Tool

Updated August 2021 • Use this fillable PDF to find out if your NIHL meets the minimum requirement for establishing a NIHL claim with the Ontario Workplace Safety and Insurance Board (WSIB).



Noise – Its Effects and Methods to Reduce Exposure

A slide presentation by James Miuccio, MSc, CIH
Occupational Hygienist.



Doing Something About Workplace Noise

A PDF infographic with exciting visuals displaying and describing the types and effects of noise, control measures and goals, as well as the benefits of noise control. 11 x 27 inches.



CCOHS: Noise – Basic Information

Fact Sheets on Noise: Easy-to-read, question-and-answer fact sheets covering a wide range of workplace health and safety topics, from hazards to diseases to ergonomics to workplace promotion.



Workers can be exposed to diesel exhaust when working near or around diesel engines. Even very low Diesel exhaust is produced by the combustion of diesel fuel. The amount of exhaust will vary widely, depending on the engine, the speed or load, the emission control systems, and for indoor exposures, the ventilation effectiveness. Diesel exhaust is a complex mixture that is confirmed to be carcinogenic (cancer-causing) to humans (IARC Group 1).

Go to Diesel Exhaust Page


Snapshot of the OHCOW Diesel Exhaust Lung Cancer Risk Calculator

Web Version of Diesel Exhaust Lung Cancer Relative Risk Calculator Now Available!

The following resources are also related to diesel exhaust:


Asbestos is a natural occurring fibrous mineral. It was used as a building material and in some fabric materials such as blankets for its fire resistance, chemical resistance, insulating properties. Asbestos use really increased in the late 1800s, and peaked in the 1960s-1970s. It began to be strictly regulated in the mid-1980s. It was not banned in Canada until 2018, though there are many existing building materials that contain it. All forms of asbestos can cause cancer when inhaled (IARC Group 1 carcinogen).

Go to Asbestos Page



Celebrating the Asbestos Ban in Canada: and Where to Go From Here

An overview of how the Canadian ban on asbestos was achieved, and identifies the challenges faced, the strategies developed and a look towards the future. Presented by Alec Farquhar, Coordinator, Asbestos Free Canada.



Investigating the Need for Asbestos Management Standards

A presentation with literature reviews, an environmental scan, interviews with key informants as well as a gap analysis and recommendations. Presented by Anya Keefe, Paul Demers, Manisha Pahwa, Soham Paraelkar at the 2020 Occ-tober Symposium.



Exposure Assessment for Newfoundland Asbestos Miners and Millers

An Abstract of an article from the Annals of Work Exposures and Health, full title: "A Quantitative Retrospective Exposure
Assessment for Former Chrysotile Asbestos Miners and Millers from Baie Verte, NL, Canada." Written by Tina Giles Murphy, Stephen Bornstein, John Oudyk and Paul Demers.



What is Asbestos?  

"Burden of Occupational Cancer Fact Sheet" from CAREX Canada and the Occupational Cancer Research Centre.



Crystalline silica (formula: silicon dioxide) is a naturally occurring mineral found in sand and stone. It is also found in human-made products such as bricks, gravel, concrete, blocks, mortar, glass, and artificial stone. Crystalline silica is often referred to as silica. Most silica is in the form quartz. Silica is hazardous when it is inhaled in the air. It is made airborne through activities such as blasting, crushing, cutting, drilling, grinding, sawing, and similar. Silica exposure can cause silicosis (a pulmonary fibrosis), lung cancer (IARCH Group 1 carcinogen), as well as chronic kidney disease, rheumatoid arthritis, and scleroderma.



Silica Control Tool logo

120,000 constructors in Ontario now have automatic access to the Silica Control Tool

Beginning in early November 2023, workers and employers in the Ontario Construction Industry will have full access to the Silica Control Tool™, its associated data, and outputs. The Tool’s user interface has undergone a facelift for Ontario and has been fully customized to meet Ontario’s health and safety regulation and standards.

More about the Silica Control Tool

Gain access the Silica Control Tool using one of these two methods:

Already have a WSIB number...

DON'T have a WSIB number...

Silica Resources:


Workers are often employed in environments, both inside and outside, that may involve exposure to both cold and heat. Understanding the health risks involved with worker in temperature extremes can help employers prepare and protect their workers. From heat stress (including heat cramps, heat exhaustion, and heat stroke) to cold stress (including frost bite, trench foot, chillbains, and hypothermia), it doesn’t have to be as “extreme” a temperature as many expect to have adverse health consequences.

Go to Temperature Page



An irritant is a chemical that causes reversible inflammation or irritation, such as itching, discomfort, sneezing, or coughing. An allergen is a usually harmless substance that triggers an immune system response, ranging from mild (itching, discomfort, sneeze) to severe (anaphylaxis, inducing asthma attacks). Some things can be both an irritant and an allergen, such as mould (mold).

Go to Allergens/Irritants Page



Respiratory Hazards

Healthy Workers in Healthy Workplaces Initiative



ODAP: Allergens and Irritants Update

A presentation by D Linn Holness



Occupational Health Issues in Agriculture

A presentation by Dr. Michael Pysklywec



WorkSafe NB: Occupational Dermatitis

Outlines causes and preventive measures that workplaces can use to minimize the risk of this disease.


Chemicals can include those are used in the workplace (including cleaning chemicals) and chemicals created in the workplace (including carbon monoxide created by sources of combustion). Chemicals can be managed by WHMIS (Workplace Hazards Materials Information System), but the CCPSA (Canada Consumer Product Safety Act) may also apply for smaller quantities of some chemicals. Chemicals can enter your body by:

  • Inhalation: breathing vapours, gases, dusts, fumes;
  • Injection, such as through anything that cuts the skin;
  • Ingestion: eating food with dirty hands may be the most common way for ingestion to occur;
  • Absorption: typically through skin, sometimes through eye contact.

Every chemical has different hazardous effects and different safe levels. Always refer to the Safety Data Sheet (SDS) for more information on the chemical’s properties, and refer to OHCOW’s OEL Adjustment Tool for OELs.

VGDF (Vapours, Gases, Dusts, Fumes)

VGDF (vapours, gases, dusts & fumes) is a broad term for inhalation hazards that have been established to increase the risk of some respiratory diseases, including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). VGDF does not have an occupational exposure limit or other maximum exposure, and will not represent a uniform exposure. Instead, VGDF represents the overall exposure to inhaled respiratory hazards. VGDF may be identified in self-reported questionnaires, job exposure matrices, or other qualitative or semi-quantitative measures of inhalational hazards.

Go to Vapours, etc Page


Chronic Obstructive Pulmonary Disease (COPD)


Chronic Obstructive Pulmonary Disease (COPD): Occurrence and Associations with Occupational Exposures and Smoking


Occupational Lung Disease: Overview, Risk Assessment, Diagnosis


OCTOBER 30, 2020

L. Christine Oliver, MD, MPH, MS



Lung Month (Work-Related Lung Disease)


OCC-TOBER 2020: Leading into November


Position Statement


The Occupational Burden of Nonmalignant Respiratory Diseases:
An Official American Thoracic Society and European Respiratory Society Statement

MOULD (Mold)

Mould (also spelled as mold) and fungal spores are ubiquitous (everywhere). Fungal spores are typically present indoors by travelling in the air from outdoors. However, mould growth should not be able to establish itself indoors. Mould needs 3 conditions to grow: a growth medium (such as drywall, wood, even dirt), temperature ideally between 20-30oC but can grow from 5-40oC, and moisture. Mould is an irritant and can be an allergen. Mould exposure can occur when there is mould growth indoors, as well as when a mould remediation is occurring.

Go to Mould Page


Web Pages

“Ontario Ministry of Labour, Immigration, Training and Skills Development: Alert: Mould in Workplace Buildings”: https://www.ontario.ca/page/alert-mould-workplace-buildings),

“Health Canada: Mould” (https://www.ontario.ca/page/alert-mould-workplace-buildings)

OHCOW Resources


Moulds – Workplace Guidelines for Recognition, Assessment, and Control

March 2001

Covering what moulds are, as well as their location, concerns, prevention, health effects, identification and safe removal of mould in the workplace

An infographic displaying mould remediation information

Mould Remediation

March 2001



Metal (& metalloid) dusts and fumes are a broad category. Each metal has different properties, and the size of the dust or fume will alter where it deposits in the respiratory tract. In many occupational settings, exposure is to multiple metals at the same time. For instance, nickel mining involves exposures more than just nickel, including: copper, cobalt, gold, silver, among others. Another example is welding, which will always result in a complex mixture of metal fumes that may include beryllium, cadmium, chromium, lead, manganese, zinc oxide, among others.

Go to Metal, Dust and Fumes Page



Mining Exposures and Health


A page with information and links to videos.



Bladder Cancer and Exposure in Ontario Mines


July 19, 2019 • Occupational exposures relating to mining as risk factors for bladder cancer


Welding Fumes


A two-page factsheet that provides an overview of the dangers of welding fumes along with the health effects, exposure sources, and prevention tips.


Kidney Cancer and Exposures in Ontario Mines


January 24, 2020 • Examing the association between kidney cancer and occupational exposure to ionizing radiation in mining.


Respiratory Hazards


November 29 2019 •  Looking at adult onset asthma that may be related to the workplace. Exposure to asbestos, diesel engine exhaust, crystalline silica and welding fumes is linked to cancer.



Background and Development of the WSIB Lung Cancer-Gold Miners Policy


December 19, 2019 • the guidelines that are considered in the adjudication of lung cancer claims from Ontario gold miners.


Sarcoidosis: Epidemiology, Pathogenesis, Diagnosis, and Causal Associations with Occupational and Environmental Exposures


March 26, 2019 • An assessment of causation in cases of sarcoidosis among workers in the mining sector of Northern Ontario.

Occupational Exposure Limit (OEL) Adjustment Tool

Updated August 2021

Based on the model and guide developed by the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST)

Brought to you by OHCOW, and the Occupational Disease Action Plan Contributors, this tool* allows the calculation of the adjusted workplace exposure limit for an unusual or extended work shift which has been adapted using the methodology set out in the Guide for the Adjustment of Permissible Exposure Values for Unusual Work Schedules (March 2015), published by Quebec's Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST).

This method, used in the Province of Quebec and referenced by the ACGIH and other health and safety organizations, considers toxicological information such as sensitization, irritation, organ toxicity, reproductive system toxicity  and teratogenicity, in addition to exposure and recovery times.

Irregular work shifts are now commonplace in many industries and the standard eight-hour work day/40 hour work week (which has been the basis for the time-weighted average (TWA) occupational exposure limits) is often not the reality. To address this change, exposure standard adjustments have increasingly become an essential component in workplace exposure assessment.

[*XCL document*]

*The file works ONLY if the macro security level of Excel is set to “enable all.”
Detailed instructions are provided at the bottom of the Tool’s Intro page by clicking on the Important arrow.

If you have questions regarding the OEL Tool, or would like to speak to an Occupational Hygienist for more information regarding exposure assessments or occupational disease prevention, please contact ask@ohcow.on.ca using OEL Adjust Tool in the subject line.


OHCOW’s mission includes a goal to protect workers and their communities from occupational diseases, injuries, and illnesses.
As part of this mission, OHCOW encourages health-based and evidence-based occupational exposure limits
(OELs) for chemicals, and equivalent sound exposure level criteria for noise exposure.

Logo of the Ontario Ministry of Labour, Training and Skills Development (MLTSD)

OHCOW has produced submissions for Ontario’s Ministry of Labour, Immigration, Training and Skills Development (MLITSD), and its predecessor ministries (MLTSD, MOL), to address evidence-based limits for Ontario regulations.

Logo of the American Conference of Governmental Industrial Hygienists

OHCOW has also produced commentary that have been submitted to the American Conference of Governmental Industrial Hygienists (ACGIH) addressing new / adjusting existing Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) for chemical and other occupational exposures.