Improving Air Cleanliness

What to know

  • Two primary methods for improving air cleanliness in the workplace include filtration and the use of germicidal ultraviolet (GUV) air treatment.
  • Filtration is delivered through central HVAC systems or through the use of portable or built-in room air cleaners.
  • GUV systems use ultraviolet lamps installed inside the HVAC system or in special fixtures near the ceiling in occupied rooms.
  • Emerging technologies should be treated with caution and require special considerations.
  • For interventions listed below that are marked with "**," please consult with professionals experienced in the proper selection, implementation, and commissioning of HVAC improvements.
HEPA filters

Prevention steps and strategies

Upgrade filter efficiency

Upgrade central HVAC filter efficiency to a Minimum Efficiency Reporting Value (MERV)-13 or better. When compatible with your HVAC system, increased filtration efficiency is especially helpful when enhanced outdoor air delivery options are limited.

Inspect HVAC system

  • Ensure ventilation systems operate properly and are up to date on maintenance.
  • Make sure air filters are properly sized and within their recommended service life.
  • Inspect filter housing and racks to ensure appropriate filter fit and minimize air that flows around, instead of through, the filter.

Use HEPA systems

Use portable or built-in high-efficiency particulate air (HEPA) fan/filtration systems (also called air cleaners or air purifiers).

  • Use HEPA systems to enhance air cleaning (especially in higher risk areas such as a medical office or areas frequently inhabited by people with a higher likelihood of having a respiratory disease and/or an increased risk of getting a respiratory disease. See FAQ #9 on HEPA filters and in-room HEPA air cleaners.
  • In-room air cleaners that use filters less efficient than HEPA filters also exist and can contribute to room air cleaning. However, they should be clearly labeled as non-HEPA units.
  • Some air cleaners/air purifiers use technologies other than filtration. See FAQ #12 for a detailed discussion of factors to consider before using these other technologies.

Use Germicidal Ultraviolet (GUV)

Germicidal ultraviolet (GUV), otherwise known as ultraviolet germicidal irradiation (UVGI), is a supplemental treatment to inactivate airborne viruses, such as SARS-CoV-2. GUV can be effective in many spaces, but it is especially useful as an additional layer of protection to reduce particles in indoor spaces that host large gatherings or where the risk of disease transmission is high. It is also helpful when options for increasing room ventilation and filtration beyond code requirements are limited.**

  • Upper-room GUV systems can be used to provide air treatment within occupied spaces.
  • In-duct GUV systems can help enhance air cleaning inside central ventilation systems.

See detailed discussion in FAQs #10 and #11.

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Content Source:
National Institute for Occupational Safety and Health