The Hierarchy of Controls
Engineering Controls
Engineering controls include isolating the exposure source and using local exhaust ventilation to minimize exposure to COVID-19. This is the most effective control strategy you can implement.
Increasing ventilation is an example of an engineering control. Consider steps to increase the delivery of clean air and dilute potential contaminants. Not all steps are applicable for all scenarios.
- Increase outdoor air ventilation, using caution when outdoor air quality is low.
- Consider running the HVAC system at maximum outside airflow for 2 hours before and after school.
- Ensure restroom exhaust fans are functional and operating at full capacity when the building is occupied.
- Inspect and maintain local exhaust ventilation in areas such as restrooms, kitchens, cooking areas, etc.
- Consider portable high-efficiency particulate air (HEPA) fan/filtration systems to enhance air cleaning (especially in higher risk areas such as the nurse's office).
- Ventilation considerations are also important on school buses.
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.
Knowledge Check Choose the best answer for the question.
2-2. What is the most effective hazard control strategy to minimize hazards associated with COVID-19?
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