The science on indoor mold is just getting off the ground but what's been learned so far could help millions of people. It targets the connection between mold and chronic sinus trouble.

Soon after identical twins Diana and Dawn Meier moved into the same apartment building, they developed breathing problems.

Diana says, "She had been complaining of a lot of sinus problems when she moved to the apartment. She had been there about a year before I did. And so I started getting like, my nose running."

Their symptoms got worse and the antibiotics doctors prescribed didn't help. Then the sisters found out they were sensitive to household mold.

When airborne, microscopic mold spores can wreak havoc in sensitive people. Researchers in one study found fungus in more than 90 percent of chronic sinusitis patients.

"They end up inhaling it into their sinus cavities and then it just breeds," says Dr. Jordan Josephson, a nasal-sinus specialist with Lenox Hill Hospital in New York.

Dr. Josephson says most sinus infections are bacterial and fungal. Antibiotics treat only bacterial infections, so patients may also need anti-fungal drugs.

Dr. Josephson says, "Each person really needs to be evaluated by their ear, nose, and throat physician or their sinus specialist so that they can figure out which is the proper combination of agents to use."

While doctors treat your sinuses, you need to attack your mold problem. You can start by washing off the fungus with bleach and water.

Occupational medicine specialist, Dr. Philip Harber says, "If a person's home has uncontrolled moisture, water leaks, et cetera, that needs to be fixed."

Dr. Harber is a mold expert and he says, "Where there's a very extensive growth, it's sometimes useful to look for advice at the EPA Web site or to call a professional."

You can hire a trained dog to sniff out hidden mold for about $500. The clean-up and repairs are left to you.

Or look in the phone book for a mold remediation expert who will do the entire job for you. It can be costly and your homeowners insurance might not pay for the work.

But as Diana and Dawn Meier found out, their health was at stake.

Homeowners insurance might pay for mold damage due to something like a broken pipe but it's not likely that you'll get financial help if the mold has been allowed to grow and cause major problems.