Question: My question regards mold in the house and air quality. I have a tenant complaining about the air quality in a house I own. It’s a very clean 15 year old home and the basement carpet is 4 years old and in excellent condition. There are no damp conditions and the climate is very dry here. I think this is a frivolous complaint giving him reason to vacate and break our lease agreement. There are no noticeable smells or signs of mold in the house or moisture anywhere in the house. In September clean water entered the basement from a broken sprinkler that was just next to the window. Within 3 hours we had thoroughly shop vaccumed about 3 gallons out of the carpet and pad, sprayed the concrete, pad and carpet with Pinesol. We then separated the layers with 2X2’s and paint cans, set up fans and opened the windows. We relaid the dry pad and carpet on the 4th day. There was no mildew stains and the musty carpet smell was minimal and had dissipated completely within 2 weeks. My tenant’s wife has Asthma and allergies. They had the house inspected and 7,553 Aspergillus/penicillium spores per cubic meter of air were shown in the basement on the report and 2071 on the main floor. Are these spores a health risk? Does this mean there is excessive mold in the house? Is this an uncommon condition for a basement? Do you think this condition was caused by the wet carpet from 4 months ago? Since there is no musty smell would these spores be dormant? Should I replace the carpet? Is the source of these spores likely to be from somewhere else in the house? Should I hire another test from a different company? I appreciate your input.
Answer: Thank you for your question(s). It’s common to have mold in the house. Currently there are no permissible levels for airborne mold spores. The large inter-individual variability in human response to exposure to different mold species and strains makes it difficult to set exposure limits. Therefore, 7,553 aspergillus/penicillium spores per cubic meter of air could be a problem to some people and not to others. Health risks depend on exposure and, for asthma symptoms, on allergic sensitization.
You have mentioned that your tenant’s wife has a history of asthma and allergies. This suggests that she could be at risk. Growth of mold in the house is due to presence of moisture. It’s possible that there were some areas that didn’t get completely dry within 48 hours and hence the growth of species of Aspergillus and/or Penicillium. These molds do not require a lot of moisture for growth. You may consider hiring a qualified professional with experience in mold investigation to come and try to determine the source of those spores and also determine whether there are still some moisture issues that you’re not aware of. They should also be able to advise you whether it’s necessary to replace the carpet or not.
Spores of Aspergillus and Penicillium species could remain dormant for many years. It’s known that even dead spores can cause allergic reactions to those who are sensitive to mold. As for your tenant, I would suggest you let them go. While the tenant’s asthma and allergies may have nothing to do with mold in the house, it’s perhaps better to let them go for their peace of mind and as a show of good will on your part.
I hope you found my comments useful. Please feel free to contact me again if you have any other questions.
Dr. Jackson Kung’u.