Without proper air circulation, indoor humidity creates the perfect environment for mold spores to take hold and grow on walls and other ceilings. Credit: Courtesy of Lara Clark

It can’t be seen, but humidity sure can be felt when it reaches high levels like those Maine has been experiencing the past several weeks. But it’s not just uncomfortable — it could also be causing danger in your home.

Humidity is the amount of water vapor in the air. The higher the humidity the hotter and wetter it feels. Inside, humidity should ideally be kept to between 30- and 50-percent, according to the U.S. Environmental Protection Agency’s guidelines. But with recent outdoor conditions including a lot of rain, it might be higher than that in your home.

Prolonged high humidity in the house can cause the perfect conditions for mold to breed.

Mold is a growth fungal spores that grows best in damp conditions. At best, it’s unsightly. But at worst, mold can cause structural damage and make people sick.

The most common molds in Maine need both darkness and moisture to be really happy, said Mike Haughton co-owner and chief of operations at SERVPRO in Bangor, a business that works in home mold meditation and removal. So areas like attics, basements and seldom-used closets are prime spots for mold to grow.

Coupled with homes that are well-sealed, and it can become a real problem.

“Many years ago we never really heard a lot about mold, but it makes sense when you think about it,” Haughton said. “Homes used to be drafty and in the 70s we were instructed to tighten up our homes to stop those drafts so we could heat our homes better.”

Mold can also grow on furniture, clothing, carpets, bedding, towels or any fabric surface in the home.

“Typically molds and dampness have a musty odor,” said Lara Clark, marketing director at Bouchard’s Cleaning and Restoration in Bangor. “That’s a good sign you have mold or a build up of moisture.”

To prevent mold from growing, you need to stop mold spores from taking up residence and reproducing.

“Mold spores are microscopic and very light and when you have good airflow, they can’t land,” Haughton said. “They are outside floating around all over the place but you don’t see [mold] growing all over, but when you put them in a box like a house, they land and reproduce.”

Running fans or opening windows to get the air moving inside can help a house breath, no matter how high the humidity outside is, Haughton said. That will help prevent growth.

Setting up a dehumidifier to collect the moisture from the air can also help. Just be sure to check it on a regular basis and empty the collected water out.

If the mold has already set in though, serious steps will need to be taken. While you can wash away mold with soap and water or bleach, it’s only a temporary fix.

There is no silver bullet that will kill mold once it has taken hold, Haughton said. If it’s bad enough, whatever it’s on may need to be removed and replaced.

“You need to get rid of that moisture,” Haughton said. “Mold has a root and when you wipe it off whatever it’s on, that root is still there and it will grow back if there is moisture for it.”

Despite the humidity, there has been some good news though.

While Clark has had a slight increase in calls from people asking about mold removal, there hasn’t been as many as she would have thought.

“I really think it’s because so many people have things like heat pumps now that help keep the indoor humidity lower,” Clark said. “Otherwise I think mold problems would have been much higher in a summer like this.”

Julia Bayly is a reporter at the Bangor Daily News with a regular bi-weekly column. Julia has been a freelance travel writer/photographer since 2000.