Course 161 Industrial Hygiene: Basic

Industrial Hygienists, Air Quality, and Hazardous Chemicals

The Industrial Hygienist

What is Industrial Hygiene - AIHA

Under the OSHA Act of 1970, OSHA develops and sets mandatory occupational safety and health requirements applicable to the more than 6 million workplaces in the U.S. OSHA relies on, among many others, industrial hygienists, or "IHs," to evaluate jobs for potential health hazards. More than 40% of OSHA's compliance officers are IHs.

Developing and setting mandatory occupational safety and health standards involves determining the extent of employee exposure to hazards and deciding what is needed to control these hazards, thereby protecting the workers.

Industrial hygienists are trained to anticipate, recognize, evaluate, and recommend controls for environmental and physical hazards that can affect the health and well-being of workers. Important IH responsibilities include:

  • Identifying, measuring and analyzing workplace health hazards and exposures (chemical, physical, biological, ergonomic) that can cause sickness, impaired health, or significant discomfort.
  • Recommending hazard control strategies to eliminate/reduce hazards and employee exposure to hazards.

The primary organization concerned with industrial hygiene is the American Industrial Hygiene Association (AIHA). AIHA is a nonprofit organization devoted to achieving and maintaining the highest professional standards for its members. More than half of the 10,000 members are certified industrial hygienists (CIHs), and many hold other professional designations. AIHA administers comprehensive education programs that keep occupational and environmental health and safety (OEHS) professionals current in the field of industrial hygiene. For more information open the AIHA Fact Sheet.

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1. Who is trained to anticipate, recognize, evaluate, and recommend controls for environmental and physical hazards that can affect the health and well-being of workers?

a. Industrial safety technicians
b. OSHA enforcement officers
c. Health compliance officers
d. Industrial hygienists

Protecting People

123rf photo
It's all about protecting workers, families, and the community.

The goal of an IH is to keep workers, their families, and the community healthy and safe. They play a vital part in ensuring that federal, state, and local laws and regulations are followed in the work environment. According to the AIHA, typical roles of an industrial hygienist include:

  • Investigating and examining the workplace for hazards and potential dangers
  • Making recommendations on improving the safety of workers and the surrounding community
  • Conducting scientific research to provide data on possible harmful conditions in the workplace
  • Developing techniques to anticipate and control potentially dangerous situations in the workplace and the community
  • Training and educating the community about job-related risks
  • Advising government officials and participating in the development of regulations to ensure the health and safety of workers and their families
  • Ensuring that workers are properly following health and safety procedures

Industrial Hygiene Focus Areas

The AIHA describes the various areas of interest that IHs place a focus. Industrial Hygienists work with issues including:

  • Indoor air quality (sick building syndrome, second-hand tobacco smoke)
  • Evaluating and controlling environmental lead exposure
  • Emergency response planning and community right-to-know
  • Occupational disease (AIDS in the workplace, tuberculosis, silicosis)
  • Potentially hazardous agents such as asbestos, pesticides, and radon gas
  • Cumulative Trauma Disorders (repetitive stress injuries, carpal tunnel syndrome)
  • Radiation (electromagnetic fields, microwaves)
  • Reproductive health hazards in the workplace
  • Setting limits on exposure to chemical and physical agents
  • Detection and control of potential occupational hazards such as noise, radiation, and illumination
  • Hazardous waste management

We'll cover some of these focus areas throughout the rest of this course.

2. Areas of interest for industrial hygienists include _____.

a. housekeeping, work schedules, and traffic awareness
b. lockout/tagout and electrical safety
c. noise, radiation, and illumination
d. fall protection, good hygiene, and diet

Worksite Analysis

gsg image worksite analysis
Analyze the workplace for air quality, chemical exposure, ergonomic issues.
(Click to enlarge)

To be effective in recognizing and evaluating on-the-job hazards and recommending controls, industrial hygienists must be familiar with the characteristics of all hazards. Major job risks can include air contaminants and chemical, biological, physical, and ergonomic hazards.

A worksite analysis is an essential first step that helps an industrial hygienist determine what jobs and work stations are the sources of these potential and existing hazards.

During the worksite analysis, the industrial hygienist measures and identifies exposures, problem tasks, and risks. The most effective worksite analyses include all jobs, operations, and work activities.

The industrial hygienist inspects, researches, or analyzes how the particular chemicals or physical hazards at that worksite affect worker health. If a situation hazardous to health is discovered, the industrial hygienist recommends the appropriate corrective actions.

3. What is the first step industrial hygienists take to determine what jobs and workstations are sources of hazards?

a. Conduct enforcement inspections
b. Perform worksite analysis
c. Conduct a records review
d. Historical search of past citations

Recognizing and Controlling Hazards

gsg image Hierarchy of Controls
Click to enlarge.

Industrial hygienists recognize several primary control strategies to eliminate or reduce health hazards and employee exposure to those hazards. These basic control strategies are further organized into a "Hierarchy of Controls." ANSI/ASSP Z10-2012, Occupational Health and Safety Management Systems, encourages employers to use the following hierarchy of hazard controls:

Hazard Control Strategies

Elimination removes the source of the hazard. This strategy totally eliminates the hazard from the workplace. This should be the top priority for all safety professionals including industrial hygienists. An example of this strategy includes replacing a hazardous chemical with a totally non-toxic, safe, "green" chemical.

Substitution reduces the hazard. This strategy should be used if it is not feasible to eliminate the hazard. The idea is to replace the hazard with a less hazardous substitute. An example would be to replace a hazardous chemical with a less hazardous one. There would still be a need for protection like personal protective equipment, but the hazards of exposure would be less serious.

Engineering controls remove/reduce the hazard through design. This strategy involves the design or redesign of tools, equipment, machinery and facilities so that hazardous chemicals are not needed or that exposure to those hazardous chemicals are not possible. Examples include using equipment that does not require the use of hazardous chemicals in a process or for cleaning. Enclosing work processes or installing general and local ventilation systems might also be used.

4. Which of the following "Hierarchy of Controls" strategies focuses on removing the source of that hazard?

a. Substitution
b. Engineering
c. Elimination
d. Administration

Exposure Control Strategies

If you have time, watch Napo in...Danger: chemicals! (10:52)

These strategies attempt to control employee behaviors to eliminate or reduce exposure to existing health hazards when hazard controls are not adequate. Naturally it's more difficult to control behaviors than hazards because we're dealing with human behavior. Exposure controls work only as long as we behave (comply).

Warnings to raise awareness of exposure to hazards. Warnings include signs, alarms, signals, labels, placards, cones, and other methods to help employees to be aware of the hazards.

Administrative controls eliminate/reduce exposure to hazards. This strategy helps to reduce exposure by developing and implementing effective training, policies, processes, procedures, practices and safety rules. Examples include scheduling production and worker tasks in ways that minimize exposure levels. The employer might schedule operations with the highest exposure potential during periods when the fewest employees are present.

Administrative controls also eliminate/reduce exposure through safe work practices. Following safe procedures while operating production and control equipment, good housekeeping, and safe practices like not eating, drinking, or smoking in regulated areas are all good examples of work practice controls.

Personal Protective Equipment (PPE) eliminates/reduces exposure through personal barriers. This strategy is generally used in conjunction with the other strategies to reduce exposure. When effective elimination, substitution and engineering controls are not feasible, appropriate PPE such as gloves, safety goggles, helmets, safety shoes, and protective clothing may be required. To be effective PPE must be individually selected, properly fitted and periodically refitted, conscientiously and properly worn, regularly maintained, and replaced as necessary.

It's important to note that administrative/work practices controls and personal protective equipment are the primary control strategies used by IHs to control exposure to health hazards in the workplace.

5. Why are exposure control strategies less effective in preventing injuries than hazard control strategies?

a. They work only as long as people behave
b. They are much more expensive to implement
c. They are not permanent in nature
d. They focus on changing the hazard, not the exposure

Indoor Air Quality

Indoor Air Quality - This Old House

Indoor air quality (IAQ) refers to the presence or absence of air pollutants in buildings. There are many sources of indoor air pollutants. Indications of potential health effects due to poor indoor air quality include:

  • the presence of sources of indoor air pollutants such as tobacco smoke and radon, or
  • conditions that promote poor indoor air quality, such as inadequate ventilation or moisture intrusion, that can lead to mold growth.

The quality of air inside offices, schools, and other workplaces is important not only for workers' comfort but also for their health. Poor IAQ has been tied to symptoms like headaches, fatigue, trouble concentrating, and irritation of the eyes, nose, throat and lungs.

Specific diseases have been linked to specific air contaminants or indoor environments, like asthma with damp indoor environments. Some exposures, such as asbestos and radon, do not cause immediate symptoms but can lead to cancer after many years.

Many factors affect IAQ. These factors include:

  • poor ventilation (lack of outside air),
  • problems controlling temperature,
  • high or low humidity,
  • recent remodeling, and
  • other activities in or near a building that can affect the fresh air coming into the building.

Sometimes, specific contaminants like dust from construction or renovation, mold, cleaning supplies, pesticides, or other airborne chemicals (including small amounts of chemicals released as a gas over time) may cause poor IAQ.

The right ventilation and building care can prevent and fix IAQ problems.

6. Which of the following air contaminants can lead to cancer after many years of exposure?

a. Asbestos and radon
b. Mold and cleaning supplies
c. Pollens and dust
d. High humidity and ultraviolet light

Outdoor Air Quality

Air Quality 101 - DEQ Louisiana (12:05)

The Clean Air Act requires the Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards for six common air pollutants. These commonly found air pollutants (also known as "criteria pollutants") are found all over the United States. They are:

  1. particle pollution (often referred to as particulate matter),
  2. ground-level ozone,
  3. carbon monoxide,
  4. sulfur oxides,
  5. nitrogen oxides, and
  6. lead.

These pollutants can harm your health and the environment, and cause property damage. Of the six pollutants, particle pollution and ground-level ozone are the most widespread health threats. EPA calls these pollutants "criteria" air pollutants because it regulates them by developing human health-based and/or environmentally-based criteria (science-based guidelines) for setting permissible levels. The set of limits based on human health is called primary standards. Another set of limits intended to prevent environmental and property damage is called secondary standards.

7. Of the six pollutants identified by the EPA as "criteria pollutants," which two are the most widespread health threats?

a. ozone and nitrogen oxides
b. carbon monoxide and lead
c. particle pollution and ground-level ozone
d. ground-level ozone and sulfur oxides

Air Contaminants


Air contaminants are commonly classified as either particulate or gas and vapor contaminants. The most common particulate contaminants include dusts, fumes, mists, aerosols, and fibers.

Gases are formless fluids that expand to occupy the space or enclosure in which they are confined. Examples are welding gases such as acetylene, nitrogen, helium, and argon; and carbon monoxide generated from the operation of internal combustion engines or by its use as a reducing gas in a heat treating operation. Another example is hydrogen sulfide which is formed wherever there is decomposition of materials containing sulfur under reducing conditions.


Fumes are formed when material from a volatilized solid condenses in cool air. In most cases, the solid particles resulting from the condensation react with air to form an oxide.

Liquids change into vapors and mix with the surrounding atmosphere through evaporation.

Mists are finely divided liquid suspended in the atmosphere. They are generated by liquids condensing from a vapor back to a liquid or by breaking up a liquid into a dispersed state such as by splashing, foaming or atomizing. Aerosols are also a form of a mist characterized by highly respirable, minute liquid particles.


Vapors are the gaseous form of substances that are normally in a solid or liquid state at room temperature and pressure. Vapors are formed by evaporation from a liquid or solid and can be found where a worker would clean and/or paint as well as where solvents are used.

Dusts are solid particles that are formed or generated from solid organic or inorganic materials by reducing their size through mechanical processes such as crushing, grinding, drilling, abrading or blasting.

Fibers are solid particles whose length is several times greater than their diameter.

8. Which of the following are formed when material from a volatilized solid condenses in cool air?

a. Fumes
b. Gases
c. Vapors
d. Mists

Toxic and Hazardous Chemicals

gsg image monitoring
Monitoring for hazardous atmospheres.

What Makes a Chemical Toxic?

The toxicity of a substance is its ability to cause harmful effects. These effects can strike a single cell, a group of cells, an organ system, or the entire body. A toxic effect may be visible damage, or a decrease in performance or function measurable only by a test. All chemicals can cause harm. When only a very large amount of the chemical can cause damage, the chemical is considered to be practically non-toxic. When a tiny amount is harmful, the chemical is considered to be highly toxic.

The toxicity of a substance depends on three factors: its chemical structure, the extent to which the substance is absorbed by the body, and the body's ability to detoxify the substance (change it into less toxic substances) and eliminate it from the body.

Are "Toxic" and "Hazardous" the Same?

No. The toxicity of a substance is the potential of that substance to cause harm, and is only one factor in determining whether a hazard exists. The hazard of a chemical is the practical likelihood that the chemical will cause harm. A chemical is determined to be a hazard depending on the following factors:

  • Toxicity: how much of the substance is required to cause harm,
  • Route of exposure: how the substance enters your body,
  • Dose: how much enters your body,
  • Duration: the length of time you are exposed,
  • Reaction and interaction: other substances you are exposed to at the same time, and,
  • Sensitivity: how your body reacts to the substance compared to other people.

Some chemicals are hazardous because of the risk of fire or explosion. These are important dangers, but are considered to be safety rather than toxic hazards. The factors of a toxic hazard are more fully explained below.

Why Are Some Chemicals More Harmful Than Others?

The most important factor in toxicity is the chemical structure of a substance (i.e., what it is made of), what atoms and molecules it contains and how they are arranged. Substances with similar structures often cause similar health problems. However, slight differences in chemical structure can lead to large differences in the type of health effect produced. For example, silica in one form (amorphous) has little effect on health, and is allowed to be present in the workplace at relatively high levels. After it is heated, however, it turns into another form of silica (crystalline) that causes serious lung damage at levels 200 times lower than amorphous silica.

9. The potential of a substance to cause harm is called its _____.

a. dose
b. toxicity
c. duration
d. selectivity

Routes of Exposure

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Skin contact with chemicals can cause severe reactions.

How Can Chemicals Enter the Body?

Exposure normally occurs through inhalation, skin or eye contact, and ingestion.

Inhalation: The most common type of exposure occurs when you breathe a substance into the lungs. The lungs consist of branching airways (called bronchi) with clusters of tiny air sacs (called alveoli) at the ends of the airways. The alveoli absorb oxygen and other chemicals into the bloodstream.

Some chemicals are irritants and cause nose or throat irritation. They may also cause discomfort, coughing, or chest pain when they are inhaled and come into contact with the bronchi (chemical bronchitis). Other chemicals may be inhaled without causing such warning symptoms, but they still can be dangerous.

Sometimes a chemical is present in the air as small particles (dust or mist). Some of these particles, depending on their size, may be deposited in the bronchi and/or alveoli. Many of them may be coughed out, but others may stay in the lungs and may cause lung damage. Some particles may dissolve and be absorbed into the blood stream, and have effects elsewhere in the body.

Skin Contact: The skin is a protective barrier that helps keep foreign chemicals out of the body. However, some chemicals can easily pass through the skin and enter the bloodstream. If the skin is cut or cracked, chemicals can penetrate through the skin more easily. Also, some caustic substances, like strong acids and alkalis, can chemically burn the skin. Others can irritate the skin. Many chemicals, particularly organic solvents, dissolve the oils in the skin, leaving it dry, cracked, and susceptible to infection and absorption of other chemicals.

Eye Contact: Some chemicals may burn or irritate the eye. Occasionally they may be absorbed through the eye and enter the bloodstream. The eyes are easily harmed by chemicals, so any eye contact with chemicals should be taken as a serious incident.

Ingestion: The least common source of exposure in the workplace is swallowing chemicals. Chemicals can be ingested if they are left on hands, clothing or beard, or accidentally contaminate food, drinks or cigarettes. Chemicals present in the workplace as dust, for example, metal dusts such as lead or cadmium, are easily ingested.

10. Which of the following is the most common route of exposure?

a. Injection
b. Skin contact
c. Inhalation
d. Ingestion

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