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Course 638 Preparing Workplaces for COVID-19

Safety guides and audits to make your job as a safety professional easier

Exposure Control Strategies

The Hierarchy of Controls

A cranes outrigging supported in muddy conditions.
The strategies at the top are most effective.
Click to enlarge.

Occupational safety and health professionals use a framework called the "hierarchy of controls" to select ways of controlling workplace hazards. In other words, the best way to control a hazard is to systematically remove it from the workplace, rather than relying on workers to reduce their exposure. During a COVID-19 outbreak, when it may not be possible to eliminate the hazard, the most effective protection measures are (listed from most effective to least effective): engineering controls, administrative controls, safe work practices (a type of administrative control), and PPE.

There are several models for the hierarchy of controls by safety professionals and training providers. Our training uses the hierarchy of controls model detailed in ANSI/ASSP Z10, Occupational & Safety Management Systems.

Click on the buttons below to see a short summary and a video of the hierarchy of controls.

  • Elimination or substitution eliminating or substituting a hazard to reduce risk.
  • Engineering controls include isolating the exposure source or using other engineering methods, such as local exhaust ventilation, to minimize exposure.
  • Warnings such as signs, barrier tape, and alarms help employees become aware of hazards.
  • Administrative controls usually involve logistic or workforce actions such as limiting the amount of time a worker performs work involving potential exposure. Good housekeeping practices to prevent surface contamination and hygiene facilities and practice to protect workers from exposure.
  • Personal Protective Equipment is used when exposure to hazards cannot be engineered completely out of normal operations or maintenance work, and when safe work practices and other forms of administrative controls cannot provide sufficient additional protection. PPE includes wearing the proper respiratory protection and clothing.

It's very important to understand that no one control measure may be totally effective against exposure. The most effective strategy to protect employees and the public is to use a combination of the hierarchy of control measures to best protect against exposure to infectious diseases. We will discuss each of the control measures in the next several sections.

1. According to OSHA, which of the following strategies would be the most effective in preventing exposure to COVID-19 during an outbreak?

a. Engineering Controls
b. A combination of strategies
c. Administrative Controls
d. Personal Protective Equipment

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Elimination and Substitution

Elimination and substitution, while most effective at reducing hazards, also tend to be the most difficult to implement in an existing process. If the process is still at the design or development stage, elimination and substitution of hazards may be inexpensive and simple to implement. For an existing process, major changes in equipment and procedures may be required to eliminate or substitute for a hazard.

These strategies are considered first because they have the potential to completely eliminate the hazard, thus greatly reducing the probability of an accident due to the hazard.

Some examples of these two strategies include:

  • Removing the source of excessive temperatures, noise, or pressure - this is "elimination".
  • Substituting a toxic chemical with a less toxic or non-toxic chemical - this is "substitution".

Engineering Controls

Air conditioning.
Local exhaust ventilation is an engineering control.
Click to enlarge.

Engineering controls to reduce exposure to infectious diseases through the design of equipment. The advantage of using engineering controls is that they reduce exposure to hazards without relying on worker behavior and can be the most cost-effective solution to implement. Engineering controls for SARS-CoV-2 and other viruses include:

  • Installing high-efficiency air filters.
  • Increasing ventilation rates in the work environment.
  • Installing physical barriers, such as clear plastic sneeze guards.
  • Installing a drive-through window for customer service.
  • Specialized negative pressure ventilation in some settings, such as for aerosol generating procedures (e.g., airborne infection isolation rooms in healthcare settings and specialized autopsy suites in mortuary settings).

Click on the button to see OSHA's guidelines on the use of ventilation.

Ensuring adequate ventilation throughout the work environment can help to maintain a safe and healthy workplace. Employers should work with a heating, ventilation, and air conditioning (HVAC) professional to consider steps to optimize building ventilation. An HVAC professional can ensure that the ventilation system is operating as intended. The following tips can help reduce the risk of exposure to the coronavirus:

  • Encourage workers to stay home if they are sick.
  • Ensure all HVAC systems are fully functional, especially those shut down or operating at reduced capacity during the pandemic.
  • Remove or redirect personal fans to prevent blowing air from one worker to another.
  • Use HVAC system filters with a Minimum Efficiency Reporting Value (MERV) rating of 13 or higher, where feasible.
  • Increase the HVAC system’s outdoor air intake. Open windows or other sources of fresh air where possible.
  • Be sure exhaust air is not pulled back into the building from HVAC air intakes or open windows.
  • Consider using portable high-efficiency particulate air (HEPA) fan/filtration systems to increase clean air, especially in higher-risk areas.
  • When changing filters, wear appropriate personal protective equipment. ASHRAE recommends N95 respirators, eye protection (safety glasses, goggles, or face shields), and disposable gloves.
  • Make sure exhaust fans in restrooms are fully functional, operating at maximum capacity, and are set to remain on.
  • Encourage workers to report any safety and health concerns.

2. Installing high-efficiency air filters is an example of _____.

a. elimination
b. mandated controls
c. engineering controls
d. substitution

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Warning tape
Comply with warning signs and tape.
Click to enlarge.


Warnings help raise general awareness about entering biohazard areas, but they do not prevent entry. Warnings work only as long as employees comply with them. Generally, warnings include signs, alarms, and labels.

All signs must be well lit and kept clean so that they are easily visible. Statements that contradict or detract from the signs' meaning are prohibited. Signs required by other statutes, regulations, or ordinances, however, may be posted in addition to, or in combination with, this sign.

3. Biohazard warning signs or tape work only as long as _____.

a. they are seen frequently
b. employees comply with them
c. administrative policies are written
d. EPA and OSHA requirements are known

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Administrative Controls

Telework can be effective to keep workers and kids home.
Click to enlarge.

Administrative controls require action by the worker or employer. Typically, administrative controls are changes in work policies, programs, processes, and procedures to reduce or minimize exposure to a hazard. Examples of administrative controls for COVID-19 and other infectious diseases include:

  • Social distancing policies.
  • Encouraging sick workers to stay at home.
  • Minimizing contact among workers, clients, and customers by replacing face-to-face meetings with virtual communications and implementing telework if feasible.
  • Establishing alternating days or extra shifts that reduce the total number of employees in a facility at a given time, allowing them to maintain distance from one another while maintaining a full onsite work week.
  • Discontinuing nonessential travel to locations with ongoing COVID-19 outbreaks. Regularly check CDC travel warning levels.
  • Developing emergency communications plans, including a forum for answering workers' concerns and internet-based communications, if feasible.
  • Providing workers with up-to-date information on COVID-19 risk factors and protective behaviors.
  • Providing hands-on training practices such as personal hygiene, cough etiquette, and use and care of PPE.

Click on the buttons below to see two short videos with discussions giving examples of administrative controls and social distancing.

4. Which of the following can be an effective administrative control?

a. Install HEPA filters in ventilation
b. A policy minimizing contact among workers
c. Washing hands regularly
d. Wearing a protective mask

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Safe Work Practices

A cranes outrigging supported in muddy conditions.
If you can't wash your hands, use hand cleaners or wipes.
Click to enlarge.

Safe work practices are types of administrative controls that include procedures for safe and proper work used to reduce the duration, frequency, or intensity of exposure to a hazard. Examples of safe work practices for SARS-CoV-2 include:

  • Use electrostatic spraying systems that delivers disinfecting solutions to the front, back, and sides of surfaces in the workplace.
  • Providing resources and a work environment that promotes personal hygiene. For example, provide tissues, no-touch trash cans, hand soap, alcohol-based hand rubs containing at least 60 percent alcohol, disinfectants, and disposable towels for workers to clean their work surfaces.
  • Requiring regular hand washing or use of alcohol-based hand rubs. Workers should always wash hands when they are visibly soiled and after removing any PPE. Post handwashing signs in restrooms.
  • Cover a sneeze or cough with a tissue or sleeve.

Click on the buttons below to see a short video on electrostatic sprayers, effective personal hygiene practices, and an NFPA warning about using hand sanitizers.

5. How much alcohol content should effective hand sanitizers contain?

a. 30 percent
b. 40 percent
c. 50 percent
d. 60 percent

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Personal Protective Equipment (PPE)

A cranes outrigging supported in muddy conditions.
A mask is not considered PPE.
Click to enlarge.

While engineering and administrative controls are considered more effective in minimizing exposure to viruses, PPE may also be needed to prevent certain exposures. While correctly using PPE can help prevent some exposures, it should not take the place of other prevention strategies.

Examples of PPE include: gloves, goggles, face shields, and respiratory facepieces. Don't think of face masks as PPE because they are used to primarily protect others, not the user. During an outbreak of an infectious disease, such as COVID-19, recommendations for PPE specific to occupations or job tasks may change depending on:

  • geographic location, updated risk assessments for workers, and
  • information on PPE effectiveness in preventing the spread of COVID-19. Employers should check the OSHA and CDC websites regularly for updates about recommended PPE.

Employers are obligated to pay for and provide their workers with PPE needed to keep them safe while performing their jobs. The types of PPE required during an outbreak will be based on the risk of being infected while working and job tasks that may lead to exposure.

All types of PPE must be:

  • Selected based upon the hazard to the worker.
  • Properly fitted and periodically refitted, as applicable (e.g., respirators).
  • Consistently and properly worn when required.
  • Regularly inspected, maintained, and replaced, as necessary.
  • Properly removed, cleaned, and stored or disposed of, as applicable, to avoid contamination of self, others, or the environment.

Click on the video below to see information on basic types of PPE.

6. Wearing a face mask is used primarily to _____.

a. primarily protect others from exposure if you are sick
b. keep you from touching your face
c. protect yourself from exposure by others if they are sick
d. give you a sense of being protected from exposure

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Respiratory Protection

A cranes outrigging supported in muddy conditions.
Facemasks and N95 Respirators.
Click to enlarge.


Unlike NIOSH-approved N95s, facemasks are loose-fitting and provide only barrier protection against droplets, including large respiratory particles. No fit testing or seal check is necessary with facemasks. Most facemasks do not effectively filter small particles from the air and do not prevent leakage around the edge of the mask when the user inhales.

The role of facemasks is for patient source control, to prevent contamination of the surrounding area when a person coughs or sneezes. Therefore they do not perform the same function as a N95 filtering facepieces and should not be considered PPE. People with confirmed or suspected COVID-19 should wear a facemask until they are isolated in a hospital or at home. The person does not need to wear a facemask while isolated. See Understanding the Difference info graphic for more information.

The CDC does not recommend that the general public routinely wear N95 respirators to protect themselves from respiratory diseases, including coronavirus (COVID-19). The best way to prevent illness is to avoid being exposed to this virus. However, as a reminder, CDC always recommends everyday preventive actions, such as hand washing, to help prevent the spread of respiratory diseases. More information.

N95 Filtering Facepiece Respirators (FFR)

Filtering facepieces are the primary respirator being used for COVID-19. An N95 FFR is a type of respirator which removes particles from the air that are breathed through it. These respirators filter out at least 95% of very small (0.3 micron) particles. N95 FFRs are capable of filtering out all types of particles, including bacteria and viruses. See approved manufacturers.

OSHA has issued temporary guidance for Using Tight-Fitting Powered Air Purifying Respirators Amid Coronavirus Pandemic. In part, the guidance says that if respiratory protection must be used, employers may consider the use of alternative classes of respirators that provide equal or greater protection compared to a N95 Filtering Facepiece Respirator, such as N99, N100, R95, R99, R100, P95, P99, and P100 respirators and NIOSH-approved, non-disposable elastomeric respirators or powered air-purifying respirators, either loose-fitting or tight-fitting. (OSHA, October 8, 2020)

Click on the button below to see an example of an approved N95 filtering facepiece.

Particulate Filtering Facepiece Respirator

For a list of N95 and other approved respirator models see the NIOSH-Approved Particulate Filtering Facepiece webpage.

The appropriate form of respirator will depend on the type of exposure and on the transmission pattern of COVID-19. See the NIOSH "Respirator Selection Logic" or the OSHA "Respiratory Protection eTool."

Click on the button below to see videos on how put on and take off face masks and N95 filtering facepieces.

7. Routine use of filtering facepiece respirators outside of workplace settings (in the community) is _____.

a. not recommend by the CDC
b. required for certain groups
c. the best way to avoid exposure
d. recommended by OSHA and EPA

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Fit Testing

Respirator fit test
Fit tests are required to ensure proper respirator fit.
Click to enlarge.

Fit testing is a procedure used to determine how well a respirator "fits"—that is, whether the respirator forms a seal on the user's face. Before any employee first starts wearing a respirator in the work environment, the employer must perform a respirator fit test. For all employees wearing negative or positive pressure tight-fitting facepiece respirators, the employer must perform either qualitative or quantitative fit tests using an OSHA-accepted fit testing protocol. In addition, employees must be fit tested whenever a different respirator facepiece is used, and at least annually thereafter.

If an employee has difficulty breathing during a fit test or while using a respirator, the employer must make a medical examination available to that employee to determine whether he or she can wear a respirator safely.

Click on the button below to see a DOL-OSHA video about respirator fit testing.

8. What action must an employer take if an employee has difficulty breathing during a respirator fit test?

a. Reassign the employee to another job
b. Do not require the use of a respirator
c. Terminate the employee's job
d. Make a medical exam available

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Respirator Inspection Requirements

Helmet, gloves, and safety glasses
Inspect respirators before each use.
Click to enlarge.

Respiratory protection is no better than the respirator in use, even though it is worn correctly. Frequent random inspections must be conducted by a qualified individual to make sure respirators are properly selected, used, cleaned, and maintained.

All respirators: For all respirators, inspections must include a check of respirator function, tightness of connections, and the condition of the various parts including, but not limited to the:

  • facepiece,
  • head straps,
  • valves,
  • connecting tube, and
  • cartridges, canisters, or filters.

It's especially important to evaluate elastic parts for pliability and signs of deterioration.

9. It is especially important for workers inspecting respirators to evaluate elastic parts for _____.

a. cracked facepiece
b. manufacturer's stamp and date
c. pliability and deterioration
d. reusability and color

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Respiratory Protection Training

Warning signs in a traffic zone.
Education includes instruction, training, and evaluation.
Click to enlarge.

Respirator training is an important part of the respiratory protection program. As you learned earlier, initial and annual respirator education should include three components: instruction, training, and evaluation to ensure employees have the necessary knowledge, skills, and abilities (KSAs) required to use respirators on the job.

Retraining must be done annually and under some conditions, additional retraining might be required. Circumstances which would require retraining include situations where:

  • changes in the type of respirator assigned to the employee render previous training obsolete;
  • when the employee has not retained the requisite understanding or skill to use the respirator properly; or
  • any other situation in which retraining appears necessary to ensure safe respirator use.

Note: If an employee has adequate KSAs, but is intentionally violating safety rules covering respiratory protection program, policies, and rules, retraining may not be the most appropriate response. More appropriately, the intentional violation of an OSHA or employer safety rule may require progressive disciplinary action, if justified


Respiratory protection training should address selection, use (including donning and doffing), proper disposal or disinfection, inspection for damage, maintenance, and the limitations of respiratory protection equipment. Learn more at OSHA's Respiratory Protection Overview.

Click on the button below to see an OSHA video on respirator program training requirements.

For more information on OSHA training requirements see OSHA Pub 2254, Training Requirements in OSHA Standards, and OSHAcademy Course 703, Introduction to OSHA Training. For more information on Respiratory Protection, see OSHAcademy Course 756.

10. When evaluating a possible retraining situation, when may progressive discipline be a more effective solution to the problem?

a. when there is a change in assigned respirator type
b. if an employee is intentionally misusing a respirator
c. when it is difficult for the employee to properly use the respirator
d. if an employee forgets how to use the respirator

Check your Work

Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.

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