Audit, Compliance and Risk Blog

Do you check for mold when reopening after COVID lockouts?

Posted by Jon Elliott on Wed, Apr 14, 2021


As vaccinations begin to bring the COVID-19 pandemic under control, more employers are moving to reoccupy and reopen workplace areas, many of which have been closed for months. During those times, residual moisture from reduced space conditioning or under-maintained facilities may have increased the possibility of mold infestations, which might endanger people returning to your workplace. This risk makes it a good time to review basic approaches to mold remediation. The remainder of this note reviews guidance from the US Centers for Disease Control and Prevention (CDC), Occupational Safety and Health Administration (OSHA), and Environmental Protection Agency (EPA).

Mold basics

Molds can grow on just about any surface, as long as moisture and oxygen are available. These opportunities are ubiquitous enough that molds and fungi are estimated to make up a quarter of all the biomass on the planet. Many types are potentially harmful to humans, including people working in inadequately ventilated “tighter” buildings constructed since the energy crisis of the 1970s. Infestations range from annoying fuzzy spots under sinks, to larger infestations in heating, ventilation and air conditioning (HVAC) systems, all the way to massive infestations in walls. Large and/or especially toxic outbreaks can lead to allergic reactions, respiratory problems and hyper-sensitivity – extreme examples are often called “sick building syndrome.” Mold infestations in buildings can also cause structural damage to the buildings and their finishings and furnishings.

Preventive measures generally consist of maintaining dry surfaces with adequate air circulation. Unfortunately, that can be easier said than done, especially in areas that are intermittently occupied or have been left vacant for extended periods.

Basic precautions where mold is a concern 

CDC recommends basic precautions when working on a moldy site, and recommends that people employ these precautions during initial reconnaissance in case they do find mold:

  • Screen people before entry. People with breathing problems such as asthma or with weakened immune systems should stay away from moldy sites. Children should not take part in disaster cleanup work. 

  • Protect breathing: wear at least an N-95 respirator to avoid inhaling mold. If mold is found and people will spend extended time removing moldy belongings or ripping out moldy carpets or drywall, they should wear a half-face or full-face respirator. CDC references OSHA’s general respiratory protection guidance for details.

  • Protect skin. Wear protective gloves (non-latex, vinyl, nitrile, or rubber). Do not touch mold or moldy items with bare hands.

  • Protect eyes. Wear goggles that provide complete eye protection. Choose goggles designed to keep out dust and small particles; safety glasses or goggles with vent holes do not protect against dust and small particles.

  • Check for other hazards. Make sure the electricity and gas are turned off and check for loose power lines or gas leaks. Look for sagging ceilings or floors or other structural problems. Watch out for wet, muddy, or slippery floors.

Basic steps for cleaning up moldy locations

If general staff members will clean up mold, CDC recommends the following steps:

  • Put on the personal protective equipment (PPE) described above to protect eyes, nose, mouth, and skin.

  • Remove standing water and wet materials. Use a wet vacuum to remove water from floors, carpets, and hard surfaces. Dry everything as quickly as possible so mold won’t start/continue growing – within 24 to 48 hours if you can.

  • Open all doors and windows while working and leave as many open as is safe when people leave.

  • Open inside doors, especially closets and interior rooms, to let air flow to all areas. Take doors off their hinges if necessary.

  • Open cabinets and bathroom vanity doors; remove drawers, wipe them clean, and stack them to dry.

  • Open the attic access to let air flow to the attic. Before you open the attic door, make sure nothing will fall on you.

  • When electricity is safe to use, use fans and dehumidifiers to remove moisture. Do not use fans if mold is already present, because fans may spread the mold.

  • Clean with water and a detergent. Remove all visible mold. Dry right away.

  • If personnel use cleaning products, do not mix cleaning products together. For example, mixing bleach and ammonia can create toxic vapors.

  • Fix the water problem completely before painting or caulking, since painting or caulking over mold will not prevent mold growth.

  • Throw away items that can’t be cleaned and dried. Throw away anything that was wet with water from outside leaks or floods that can’t be cleaned and dried completely within 24 to 48 hours. 

These recommendations are consistent with those published by OSHA (which I discussed HERE). Readers should note that OSHA distinguishes four basic levels/extents of mold contamination, which imply different levels of response:

  • Level I (small isolated areas) --no more than 10 square feet

  • Level II (mid-sized isolated areas) --10 to 30 square feet

  • Level III (large isolated areas) --30 to 100 square feet

  • Level IV (extensive contamination) --more than 100 square feet of contiguous contamination

When should experts be called?

CDC notes that non-professionals may or may not reliably remediate mold-infested areas. As practical tips:

  • “If you still see or smell mold, you have more work to do. After a remediation, there should be no signs of water damage or mold growth.

  • You may need to ask a mold remediation professional to know whether your mold problem is completely fixed. As noted in the “Should I do this myself?” section, sampling for mold is not usually recommended; instead, a careful inspection of the work area for completion of the cleanup and absence of mold-related odors is usually appropriate.

  • If you have health problems that get worse when you return home [or to the office, for purposes of this note], like asthma or allergy attacks or skin or eye irritation, you may still have some mold.”

What’s next?

As organizations reoccupy spaces that have been less- or non-utilized during COVID-19 shutdowns, they should assess their structures and workspaces for possible contamination, including mold that may have grown in damp or poorly ventilated areas. The CDC guidelines described above provide systematic guidance for doing so.

Self-Assessment Checklist

Do the organization’s operations and maintenance (O&M) programs at its facilities including:

  • Inspection and O&M activities designed to minimize the accumulation of moisture at locations within facilities?

  • Programs to identify, evaluate and remediate mold infestations?

Does the organization own or operate any facility in areas prone to flooding from precipitation runoff including from hurricanes?

  • If so, has the organization established hurricane preparedness and response plans for each such facility?

Has the organization maintained these preventive maintenance activities during any COVID-related slowdowns or shutdowns?

  • If not, has the organization established procedures for site inspections and remediation upon reopening?

Where Can I Go For More Information?

CDC’s Mold portal 

OSHA’s Molds safety and health topic portal

EPA’s Mold portal

Smithsonian Museum Conservation Institute’s Mold and Mildew portal

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About the Author

Jon Elliott is President of Touchstone Environmental and has been a major contributor to STP’s product range for over 30 years. 

Mr. Elliott has a diverse educational background. In addition to his Juris Doctor (University of California, Boalt Hall School of Law, 1981), he holds a Master of Public Policy (Goldman School of Public Policy [GSPP], UC Berkeley, 1980), and a Bachelor of Science in Mechanical Engineering (Princeton University, 1977).

Mr. Elliott is active in professional and community organizations. In addition, he is a past chairman of the Board of Directors of the GSPP Alumni Association, and past member of the Executive Committee of the State Bar of California's Environmental Law Section (including past chair of its Legislative Committee).

You may contact Mr. Elliott directly at:

Tags: EPA, mold, Coronavirus, CDC, Covid-19