Got mold?

Photo: Ralf Geithe/iStockphoto

Mold is virtually everywhere. It’s on every continent, in the foods we eat (say “cheese”) and in lifesaving medicine. It plays a key role in nature, breaking down dead organic matter and keeping it from piling up around us.

Mold has been around “as long as humans have lived in buildings,” said Donald Weekes, a member of the American Conference of Governmental Industrial Hygienists’ board of directors. “It’s not going to go away anytime soon.”

For some people, mold can lead to health problems. Employers should take steps to avoid mold-related health issues in the workplace – typically respiratory symptoms – by staying up to date on facility inspections and maintenance. Those inspections are especially important for employers reopening buildings or facilities that have sat vacant during the COVID-19 pandemic.

The basics for life

Mold needs only a few elements to grow and thrive: oxygen, moisture and a food source. In buildings, it’s commonly found on materials such as the paper backing on drywall, cellulose ceiling tiles or wood framing.

The most effective control methods focus on the presence of moisture or water, which can enter buildings in various ways.

“Dampness can occur from water intrusion such as leaks in roofs, windows or pipes, and from high indoor humidity or condensation,” said NIOSH medical officer Rachel Bailey and research industrial hygienist Ju-Hyeong Park, both of whom are from the agency’s Respiratory Health Division. “Water intrusion can also occur through concrete slabs or flooding incidents.”

Brendan Moriarty, vice president of risk engineering and executive field specialist for Chubb North America Risk Engineering, and Matt Johnson, a certified industrial hygienist and certified safety professional as well as regional manager with Chubb Global Risk Advisors, highlighted some other causes of moisture issues. One is a building’s heating, ventilation and air conditioning system.

For example, improper operation of an air conditioner “can result in elevated humidity inside a facility,” Moriarty and Johnson said. “Ideally, a building’s humidity should remain below 60%, and ideally between 30% and 50%.”

Another consideration to take into account is whether the building or facility was constructed in the 1970s. Many structures built during that decade were “sealed tightly” for energy efficiency, the pair noted, which in some cases “resulted in diminished ventilation, contributing to moisture vapor buildup.”

Inspect and react quickly

The process for curbing mold growth should begin with a formal mold management strategy, Moriarty and Johnson said. This can address situations such as elevated humidity levels, roof leaks or any other sources of water intrusion such as flooding.

The strategy should include regularly scheduled facility inspections, Weekes added.

The Environmental Protection Agency, in its guidance document “Mold Remediation in Schools and Commercial Buildings,” says indoor mold growth “may not be obvious” and that it can grow on “hidden surfaces” such as the back sides of drywall, wallpaper or paneling; the top of ceiling tiles; and the underside of carpets or pads.

Hidden mold locations also may include pipe chases, utility tunnels, walls behind furniture, condensate drain pans inside air-handling units, porous thermal or acoustic liners inside ductwork, or roof materials above ceiling tiles (as a result of roof leaks or insufficient insulation).

Moisture meters are one tool that can help determine the moisture content or dampness in building materials. The meters usually feature a probe(s) that is inserted into the materials or pressed against the surface.

Any sign of water intrusion should be addressed as soon as possible, and the drying of those materials or areas should begin within 24 to 48 hours.

“The best things are prevention and immediate reaction,” Weekes said. “If you can address the water intrusion right away, that’s going to prevent or reduce the potential for most mold growth.”

NIOSH has materials to help assess signs of water damage or dampness in buildings, accessible at However, your eyes and nose can be just as useful.

If you detect a musty, earthy smell in the air, it’s a good sign you might have a mold and/or water intrusion issue, said Jack Springston, vice chair of the ACGIH Bioaerosols Committee and industrial hygiene services manager at ATC Group Services LLC.

Likewise, “if you have wet surfaces and you’ve got what looks like mold growing there, it probably is,” he added.

On the other hand, what you’re seeing might not actually be mold. In some cases, Springston said, it could be efflorescence – deposits of salts on surfaces that may appear powdery or crystalline. It can indicate that your building has a chronic moisture issue that needs to be addressed.

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