You can run but you can't hide
Courtesy of ThisOldHouse.com
With more than 100,000 species worldwide, roughly a thousand of which are native to the United States, molds are literally everywhere on the planet, including Antarctica. In nature, these fungi serve as a catalyst—speeding decomposition and ridding the planet of megatons of dead plant matter. And some varieties even have a time-honored place within our homes. After all, you owe the penicillin in your medicine cabinet to a mold called Penicillium chrysogenum, part of the same genus as Penicillium roqueforti, the mold you can thank for that delightful Roquefort cheese stinking up your fridge.
But no good can come from uninvited mold (aka mildew) indoors, since these microscopic organisms make their living by consuming the surface they're growing upon. It's bad enough when their food source is a little soap scum in your shower, but when it's the cellulose in wallboards or ceiling tiles, or worse yet, in the wooden studs that support them, the resulting property damage can be significant. Even more serious are the potential health effects for your home's occupants.
Photo: This Old House/Danielle Boyce Batten
When it rains...
In 2005, it was an all-too-familiar sight in the media: homes deluged by the flood waters of Hurricane Katrina. Less ubiquitous, however, were images of the secondary setback suffered by New Orleans homeowners: an onslaught of aggressive mold left behind by the receding waters, an example of which can be seen in this photo taken less than a month after the storm hit, showing the scarred walls of Danielle Boyce Batten's home in Lakeview, where the 17th Street Canal levee was breached.
Photo: This Old House/Danielle Boyce Batten
"The first time I went back, I wore a mask and only stayed ten or fifteen minutes," Danielle recalls. "There was a moldy smell, and it just affected your whole sinuses. You really could feel it. It burned your throat, it burned your eyesI mean, it was that strong." Danielle's family members have suffered with health problems that she attributes to their mold exposure. "My sister Dionne was the first person to get into the house," Danielle says, "and she developed some sort of upper-respiratory condition that the doctors in Baton Rouge thought was caused by the mold." Last September, Danielle and her husband had the home demolished. "The mold," she says, "was one of many factors in our decision."
Public health crisis
"We have studies that show we have volumes of mold in New Orleans that have never been seen in any other city in this country before," says Dr. Kevin Stephens, Director of the City of New Orleans Health Department. "The long-term health effects are only theoretical, because we don't have any comparable case in history, but in the short-term we do know that mold is one of the known triggers of bronchial constriction."
Molds reproduce by releasing spores that can provoke allergic reactions ranging from the mild (itchy eyes, runny nose, head congestion, coughing) to the more severe (skin rashes and worsened asthma). "We have a prevalence of asthma, specifically in children, of about 15%. That's a very high rate," Dr. Stephens says. "Anything that can trigger airway obstruction and an asthma attack is problematic."
Photo: This Old House/Betsy Andrews
"Mold should not be the determining factor in the demolition of a house," says Dr. Stephens, "but it can be a criterion in deciding to gut a housebecause if you have mold behind your walls, it's very difficult to get rid of." Simply waiting for flood waters to evaporate is not a viable option, as that could take months or even years, during which mold constantly works its mischief. "If you have a significant amount of mold, as in 60% of your walls being covered with it, we recommend that you actually remove the sheetrock and dry your house out," he says. "It's like a fruit bowl: If you have mold on just one orange, you can throw that one away and keep the rest. But if most of the fruit is covered with mold, it's best to throw it all out."
A different black plague
Though many mold species can grow indoors, the list of usual suspects is much shorterand one variety gets the lion's share of attention. Columbia University's Dr. Ginger Chew studies asthmas and allergies related to mold. "When people think of mold, they usually mention toxic black mold, or Stachybotrys chartarum," she notes. This home invader defends itself from rival microorganisms by releasing poisons called mycotoxins, which can cause serious illness in humans. "Mycotoxins tend to inhibit protein synthesis, which your body needs to survive," says Dr. Chew. "They can cause hemorrhaging in various body tissues."
Regardless of the variety, "mold growth should always be taken care of, whether you have the chartarum or not," says Dr. Chew, "as all molds have the potential to pose health risks." Don't waste your time trying to determine what kind of mold you have. For one thing, it's probably a futile effort. "There's a lot of cross-reactivity between species," she says, "so it's hard to figure out which mold is which." And even if you're not allergic now, don't count on staying that way; as Dr. Chew points out, "People can develop allergies throughout their lives."
Besides, even people who aren't allergic can be adversely affected. "That musty, moldy odor comes from volatile organic compounds, which are mainly alcohols and ketones," says Dr. Chew. "Inhaling alcohol for a long time, in sufficient quantity, can result in headaches, watery eyes, mucous membrane irritationand that can affect anyone."