By Evan Hill, Healthy Air USA

As a professional certified mold remediator, I have been remediating buildings and performing mold inspections for seven years. I live in a neighborhood about eight years old. One Saturday, a neighbor was out walking her dog while I was working in the yard and stopped to chit chat a few minutes. She was familiar with the work I do and began to tell me she believed her home was making her sick – something I often hear in my line of work. She spoke of chronic fatigue, chronic sinus infections, headaches and that she no longer had the energy for her daily jogs around the neighborhood. She also claimed she felt much better while away from home on a recent vacation in Florida. I offered to do a mold inspection to see if I could find any problems that might be causing her illness.

The first thing I did was walk the perimeter of the house to check for drainage problems. The house was located on a hill with the yard sloping away from the house on all sides. The gutter system was in good condition with underground drains carrying the water away from the house. When I entered the house a faint musty smell hit me, an almost certain indication of mold growth. I proceeded with my mold inspection on the home’s main level. The floors were finished with hardwood and terra cotta tile and the moisture in the hardwood was 12% – a level too low to support mold growth. Checking moisture in hardwood is a good barometer for determining if conditions exist to sustain mold growth. Humidity can change dramatically just by opening and closing doors, but hardwood flooring absorbs moisture slowly and gives up moisture slowly – so it is a good indication if humidity levels are often elevated. I finished my mold inspection on the main floor by checking inside cabinets around plumbing connections and a closet on a perimeter wall. There was no visible sign of mold so I proceeded to the finished basement.

The basement floors were also finished with hardwoods. There was no visible mold on any of the walls but I could still smell mold and proceeded to try and sniff it out like one of the mold dogs we hear about might do. I checked above the dropped ceiling and the wood looked new and had no visible mold. Finally, in one small storage room, I found a small amount of mold on a base plate. But after finding the moisture level in the wood was less than ten percent, I knew the mold had to dormant. The real problem must be somewhere else.

I proceeded next to the mechanical room in the unfinished portion of the basement. Immediately I spotted the source sustaining the mold growth. The return and supply air plenums (or mixing boxes) connecting the air ducts to the furnace and air conditioner were made of fiberglass duct board sheeting. Duct board is a coarse, porous material. As air circulates through the air ducts, particles or dust collect on the fiberglass. When the air conditioner is running, moisture condenses on the evaporator or cooling coil and then migrates into the plenums. The combination of dust particles and moisture becomes a food source for mold.

I used my pocket knife to cut a twelve inch square inspection hole. The inside of the supply plenum was covered with a thick, black, furry layer of mold. With a flashlight I showed her the sample piece I cut from the sheeting and the inside of the plenums.

I recommended that she replace all of the duct board with sheet metal and insulate the plenums with metallic bubble wrap insulation on the outside – not fiberglass insulation. I often find fiberglass in air sample tests. Additionally, I recommend she have the remaining air ducts cleaned and sanitized by a company that uses a truck mounted vacuum system because of the tremendous amount of air it moves.

Just before writing this, my neighbor told me that it has been fourteen months since her last occurrence of a sinus infection and she is no longer plagued by chronic fatigue. The Mayo Clinic claims almost all chronic sinus infections are caused by mold. Surely mold must have been the reason for her recurring sinus infections.

It really makes me fell good when I see her jogging on our neighborhood streets – kind of like a doctor must feel when he or she has helped someone recover from a hard to diagnose illness.