Course 161 Industrial Hygiene: Basic

Biological and Physical Health Hazards

Biological Hazards

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Biological hazards are common in laboratories and clinics.

Biological hazards include bacteria, viruses, fungi, and other living organisms that can cause acute and chronic infections by entering the body either directly or through breaks in the skin. Occupations that deal with plants or animals or their products or with food and food processing may expose workers to biological hazards. Laboratory and medical personnel also can be exposed to biological hazards. Any occupations that result in contact with bodily fluids pose a risk to workers from biological hazards.

In occupations where animals are involved, biological hazards are dealt with by preventing and controlling diseases in the animal population as well as properly caring for and handling infected animals. Also, effective personal hygiene, particularly proper attention to minor cuts and scratches especially on the hands and forearms, helps keep worker risks to a minimum.

In occupations where there is potential exposure to biological hazards, workers should practice proper personal hygiene, particularly hand washing. Hospitals should provide proper ventilation, proper personal protective equipment such as gloves and respirators, adequate infectious waste disposal systems, and appropriate controls including isolation in instances of particularly contagious diseases such as tuberculosis.

1. In occupations where there is potential exposure to biological hazards, workers should practice proper personal hygiene, particularly _____.

a. hand washing
b. air blowing clothes
c. nasal sprays
d. masks

Biological Agents

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Deer ticks cause disease.

Biological agents include bacteria, viruses, fungi, other microorganisms, and their associated toxins. They have the ability to adversely affect human health in a variety of ways, ranging from relatively mild allergic reactions to serious medical conditions, even death. These organisms are widespread in the natural environment; they are found in water, soil, plants, and animals. Because many microbes reproduce rapidly and require minimal resources for survival, they are a potential danger in a wide variety of occupational settings.

This page provides a starting point for technical and regulatory information about some of the most virulent and prevalent biological agents.

Anthrax: Anthrax is an acute infectious disease caused by a spore-forming bacterium called Bacillus anthracis. It is generally acquired following contact with anthrax-infected animals or anthrax-contaminated animal products.

Avian Flu: Avian influenza is a highly contagious disease of birds which is currently epidemic amongst poultry in Asia. Despite the uncertainties, poultry experts agree that immediate culling of infected and exposed birds is the first line of defense for both the protection of human health and the reduction of further losses in the agricultural sector.

Bloodborne Pathogens and Needlestick Prevention: OSHA estimates that 5.6 million workers in the health care industry and related occupations are at risk of occupational exposure to bloodborne pathogens, including human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), and others.

Botulism: Cases of botulism are usually associated with consumption of preserved foods. However, botulinum toxins are currently among the most common compounds explored by terrorists for use as biological weapons.

Coronavirus Influenza: Infection with the novel coronavirus, officially named SARS-CoV-2, which causes the Coronavirus Disease 2019 (COVID-19) can cause illness ranging from mild to severe and, in some cases, can be fatal. Most people experience symptoms such as fever (the most common symptom), dry cough, shortness of breath, and general aches and pains.

Foodborne Disease: Foodborne illnesses are caused by viruses, bacteria, parasites, toxins, metals, and prions (microscopic protein particles). Symptoms range from mild gastroenteritis to life-threatening neurologic, hepatic, and renal syndromes.

Hantavirus: Hantaviruses are transmitted to humans from the dried droppings, urine, or saliva of mice and rats. Animal laboratory workers and persons working in infested buildings are at increased risk to this disease.

2. Which of the following biological agents is usually associated with consumption of preserved foods?

a. Anthrax
b. Botulism
c. Hantavirus
d. Avian flu

Biological Agents (Continued)

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Mosquitos cause West Nile Virus.

Legionnaires' Disease: Legionnaires' disease is a bacterial disease commonly associated with water-based aerosols. It is often the result of poorly maintained air conditioning cooling towers and potable water systems.

Mold: Molds produce and release millions of spores small enough to be air-, water-, or insect-borne which may have negative effects on human health including allergic reactions, asthma, and other respiratory problems.

Plague: The World Health Organization reports 1,000 to 3,000 cases of plague every year. A bioterrorist release of plague could result in a rapid spread of the pneumonic form of the disease, which could have devastating consequences.

Ricin: Ricin is one of the most toxic and easily produced plant toxins. It has been used in the past as a bioterrorist weapon and remains a serious threat.

Severe Acute Respiratory Syndrome (SARS): Severe acute respiratory syndrome (SARS) is an emerging, sometimes fatal, respiratory illness. According to the Centers for Disease Control and Prevention (CDC), the most recent human cases of SARS were reported in China in April 2004 and there is currently no known transmission anywhere in the world.

Smallpox: Smallpox is a highly contagious disease unique to humans. It is estimated that no more than 20 percent of the population has any immunity from previous vaccination.

Tularemia: Tularemia is also known as "rabbit fever" or "deer fly fever" and is extremely infectious. Relatively few bacteria are required to cause the disease, which is why it is an attractive weapon for use in bioterrorism.

Viral Hemorrhagic Fevers (VHFs): Along with smallpox, anthrax, plague, botulism, and tularemia, hemorrhagic fever viruses are among the six agents identified by the Centers for Disease Control and Prevention (CDC) as the most likely to be used as biological weapons. Many VHFs can cause severe, life-threatening disease with high fatality rates.

3. Which of the following is a highly contagious disease unique to humans?

a. Plague
b. Ricin
c. Tularemia
d. Smallpox

Physical Health Hazards

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Vibration, hazardous atmospheres, and noise are three common physical hazards.

Physical health hazards that employees face include excessive levels of ionizing and nonionizing electromagnetic radiation, noise, vibration, illumination, and temperature and humidity extremes. Throughout the rest of this module, we'll briefly look at each of the following common types of physical hazards encountered by employees in the workplace. Industrial hygienists routinely analyze workplaces for these hazards and exposures.

Radiation: In occupations where there is exposure to ionizing radiation, time, distance, and shielding are important tools in ensuring worker safety. Danger from radiation increases with the amount of time one is exposed to it; hence, the shorter the time of exposure the smaller the radiation danger.

Noise: Noise, another significant physical health hazard, can be controlled by various measures. Noise can be reduced by controlling the noise at the source and by controlling exposure to the noise.

Temperature and humidity: Another physical hazard, radiant heat exposure in factories such as steel mills, can be controlled by installing reflective shields and by providing protective clothing.

Illumination: Illumination in the workplace is an important consideration. Inadequate or too much illumination in the work area can cause eye strain. Work environments that are too dark can possibly cause injuries from tripping and falling.

Ergonomics: Most workplace injuries and physical disorders are caused by the hazards associated with poor ergonomics. Strains, sprains, repetitive motion injuries, and musculoskeletal disorders are common in the workplace. Unfortunately, OSHA does not have specific mandatory standards that address proper ergonomics.

4. Most workplace injuries and physical disorders are caused by the hazards associated with _____.

a. noise
b. ergonomics
c. machine guarding
d. radiation


Ionizing & Non-Ionizing Radiation

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Ionizing and Non-Ionizing Radiation Chart
(Click to enlarge)

Radiation includes a wide range of energies forming the electromagnetic spectrum, which is illustrated to the right. The energy of the radiation shown on the spectrum to the right increases from left to right as the frequency rises. The spectrum has two major divisions:

  • Non-ionizing radiation: Radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as "non-ionizing radiation." Examples of this kind of radiation are sound waves, visible light, and microwaves.
  • Ionizing radiation: Radiation that falls within the ionizing radiation range has enough energy to remove tightly bound electrons from atoms, thus creating ions. This is the type of radiation that people usually think of as 'radiation.' We take advantage of its properties to generate electric (nuclear) power, to kill cancer cells, and in many manufacturing processes.

Time, Distance, and Shielding

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Exposure to gamma rays and free neutrons require the most shielding.

Time, distance, and shielding actions minimize your exposure to radiation in much the same way as they would to protect you against overexposure to the sun:

  • Time: For people who are exposed to radiation in addition to natural background radiation, limiting or minimizing the exposure time reduces the dose from the radiation source.
  • Distance: Just as the heat from a fire reduces as you move further away, the dose of radiation decreases dramatically as you increase your distance from the source.
  • Shielding: Barriers of lead, concrete, or water provide protection from penetrating gamma rays and x-rays. This is why certain radioactive materials are stored under water or in concrete or lead-lined rooms, and why dentists place a lead blanket on patients receiving x-rays of their teeth. Therefore, inserting the proper shield between you and a radiation source will greatly reduce or eliminate the dose you receive.​

5. Lead shielding is used by dentists to protect against _____.

a. free neutrons
b. beta rays
c. X-rays
d. alpha particles


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Repeated high-impact noise can cause permanent hearing loss.

Exposure to high levels of noise can cause permanent hearing loss. Neither surgery nor a hearing aid can help correct this type of hearing loss.

  • Short term exposure to loud noise can also cause a temporary change in hearing (your ears may feel stuffed up) or a ringing in your ears (tinnitus).
  • Repeated exposures to loud noise can lead to permanent tinnitus and/or hearing loss.

Noise-induced hearing loss limits your ability to hear high frequency sounds, understand speech, and seriously impairs your ability to communicate. Noise may be a problem in your workplace if:

  • You hear ringing or humming in your ears when you leave work.
  • You have to shout to be heard by a coworker an arm's length away.
  • You experience temporary hearing loss when leaving work.
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How loud is the workplace?
(Click to enlarge)

OSHA Requirements

OSHA sets legal limits on noise exposure in the workplace. These limits are based on a worker's time weighted average over an 8-hour day (called a 8-Hour TWA). With noise, OSHA's permissible exposure limit (PEL) is an average of 90 decibels (dBA) for all workers for an 8-hour day.

The OSHA standard uses a 5 dBA exchange rate. This means that when the noise level is increased by 5 dBA, the amount of time a person can be exposed to a certain noise level to receive the same dose is cut in half.

OSHA's requirement to protect all workers in general industry calls for employers to implement a Hearing Conservation Program where workers are exposed to a time weighted average noise level (called the "action level") of 8-Hour TWA of 85 dBA or higher.

Hearing Conservation Programs require employers to measure noise levels, provide free annual hearing exams, free hearing protection, and training.

6. A hearing conservation program is required if exposure to the "action level" of _____ is experienced by employees.

a. 90 dBA or more
b. at least 80 dBA
c. 80 dBA or more
d. 85 dBA or higher

Noise (Continued)

Reducing Noise Hazards

Noise controls are the first line of defense against excessive noise exposure. The use of these controls should aim to reduce the hazardous exposure to the point where the risk to hearing is eliminated or minimized. With the reduction of even a few decibels, the hazard to hearing is reduced, communication is improved, and noise-related annoyance is reduced. There are several ways to control and reduce worker exposure to noise in a workplace.

Engineering Controls: Engineering controls involve modifying or replacing equipment, or making related physical changes at the noise source or along the transmission path to reduce the noise level at the worker's ear. Examples of inexpensive, effective engineering controls include some of the following:

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Examples of Engineering Controls
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  • Choose low-noise tools and machinery.
  • Maintain and lubricate machinery and equipment.
  • Place a barrier between the noise source and employee.
  • Enclose or isolate the noise source.

Administrative Controls: These are changes in the workplace that reduce or eliminate worker exposure to noise. Examples include:

  • Operating noisy machines during shifts when fewer people are exposed.
  • Limiting the amount of time a person spends at a noise source.
  • Providing quiet areas where workers can gain relief from hazardous noise sources.
  • Restricting worker presence to a suitable distance away from noisy equipment.

Hearing protection devices (HPDs): Hearing personal protection equipment (PPE) such as earmuffs and plugs, are considered an acceptable but less desirable option to control exposures to noise. HPDs are generally used during the time necessary to implement engineering or administrative controls, when such controls are not feasible, or when worker's hearing tests indicate significant hearing damage.

7. Which of the following is an example of an engineering control to reduce the noise level of a machine?

a. Operate machines when workers are not present
b. Limit the amount of exposure time
c. Enclose the machine with sound-absorbing material
d. Provide a quiet area for workers

Excessive Heat and Humidity

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When it's too hot, health, attitudes, and productivity suffer.

As a general rule, office temperature and humidity are matters of human comfort. OSHA has no regulations specifically addressing temperature and humidity in an office setting. However, OSHA recommends removing air contaminants and/or controlling room temperature and humidity. OSHA recommends temperature control in the range of 68-76 degrees Fahrenheit and humidity control in the range of 20%-60%.

Operations involving high air temperatures, radiant heat sources, high humidity, direct physical contact with hot objects, or strenuous physical activities have a high potential for inducing heat stress in employees. These workplaces include: iron and steel foundries, brick-firing and ceramic plants, glass products facilities, electrical utilities (particularly boiler rooms), bakeries, commercial kitchens, laundries, food canneries, chemical plants, mining sites, and smelters.

Outdoor operations conducted in hot weather, such as construction, refining, asbestos removal, and hazardous waste site activities, especially those that require workers to wear semipermeable or impermeable protective clothing, are also likely to cause heat stress among exposed workers.

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Protective clothing is important in hot work environments.


There are five primary engineering and administrative control methods to control exposure to excessive heat in the workplace:

  1. Ventilation,
  2. air cooling,
  3. fans,
  4. shielding, and
  5. insulation

Heat reduction can also be achieved by using power assists and tools that reduce the physical demands placed on a worker.

8. OSHA recommends temperature control in the range of _____ Fahrenheit and humidity control in the range of _____.

a. 45-66 degrees; 65%-70%
b. 51-69 degrees; 10%-15%
c. 68-76 degrees; 20%-60%
d. 75-82 degrees; 40%-70%



Inadequate or poor-quality lighting systems can lead to slips, trips, and falls, shocks and burns, and inability to quickly exit a space.

Temporary lights should have guards or be recessed to prevent accidental contact with the bulb. They should be equipped with heavy duty electric cords, not be suspended by electric cords, and they should be equipped with overcurrent protection such as fuses or circuit breakers. In dark areas without temporary lighting available, provide flashlights or light sticks. Make sure workers do not enter dark spaces without suitable portable light.


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Poor ergonomic practices account for most injuries in the workplace.

The science of ergonomics studies and evaluates a full range of tasks and how they impact the health of the worker. Tasks evaluated include lifting, lowering, pushing, pulling, holding, and twisting. Back injuries are more likely to occur when an employee does any of these tasks while twisting.

Many ergonomic problems result from technological changes such as increased assembly line speeds, adding specialized tasks, and increased repetition; some problems arise from poorly designed job tasks. Any of these conditions can cause ergonomic hazards such as excessive vibration and noise, eye strain, repetitive motion, and heavy lifting problems. Improperly designed tools or work areas also can be ergonomic hazards.

Repetitive Motion

Repetitive motions or repeated shocks over prolonged periods of time as in jobs involving sorting, assembling, and data entry can often cause irritation and inflammation of the tendon sheath of the hands and arms, a condition known as carpal tunnel syndrome.

Repetitiveness is influenced by machine or line pacing, piece work, and unrealistic deadlines. For instance, an experienced worker packing apples (piece work) may complete many more similar exertions or movements than a new worker. Unfortunately, he or she may be performing at such a rapid rate that they may injure themselves over time. However, repetition alone is not an accurate predictor of injury. Other factors like force, posture, duration, and recovery time must also be considered.

9. Back injuries are more likely when an employee _____ while pushing, pulling, lifting, or lowering objects.

a. moves
b. twists
c. reaches
d. holds

Ergonomics (Continued)


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Vibration can lead to hand-arm syndrome (HAVS).

Various kinds of tools may cause vibration that could lead to "white finger" or hand-arm vibration syndrome (HAVS). This is especially dangerous when proper damping techniques are not applied, if machines are not maintained, if tools are not alternated, or if a worker uses a vibrating tool for consecutive hours during a workday. Workers need to be trained on the hazards of working with vibrating tools, and should always allow the tool or machine to do the work.

Controls to help reduce vibration hazards include vibration isolators or damping techniques on equipment, isolating machine vibrations from the work surface, and use of dampening material. Also, make sure rotating shafts are balanced, restrict the duration of exposure, and train workers on the hazards of vibrating parts.

Avoiding Hazards

Ergonomic hazards are avoided primarily by the effective design of a job or jobsite and better designed tools or equipment that meet workers' needs in terms of physical environment and job tasks. Through thorough worksite analyses, employers can set up procedures to correct or control ergonomic hazards by:

  • using the appropriate engineering controls (e.g., designing or re-designing work stations, lighting, tools, and equipment);
  • teaching correct work practices (e.g., proper lifting methods);
  • employing proper administrative controls (e.g., shifting workers among several different tasks, reducing production demand, and increasing rest breaks); and,
  • if necessary, providing and mandating personal protective equipment. Evaluating working conditions from an ergonomics standpoint involves looking at the total physiological and psychological demands of the job on the worker.

Overall, industrial hygienists point out that the benefits of a well-designed, ergonomic work environment can include increased efficiency, fewer accidents, lower operating costs, and more effective use of personnel.

10. Which of the following is NOT effective in reducing vibration hazards?

a. Use dampening material
b. Balancing rotating shafts
c. Increasing the frequency by half
d. Restrict the duration of exposure

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