Mold Allergy – FAQ

Originally Published 2006

Q. What are mold allergies?

A. Just like pollens, mold spores can cause allergies in sensitive individuals.

Q. Are there different types of mold allergens to which we are allergic?

A. Yes. There are a large number of different molds that occur, both indoors (water damaged areas) and outdoors that can cause allergies. Virtually any mold can cause an allergic reaction in sensitive individuals.


Q. Where do mold allergens grow indoors?

A. Molds grow on living (pathogens of plants or animals) and especially on dead plants and animals where they are involved in the natural decay process.
TopQ. What are outdoor mold allergens?
A. These are the ones that are mostly involved in the decay process or sometimes in plant diseases.

Q. If I want to avoid outdoor mold allergens, what are likely to be the places I should avoid most?

A. Fields and moist habitats with many plants.

Q. How can I reduce mold allergens in my home?

A. The best methods are to eliminate or limit carpeting as much as possible as they can be reservoirs for spores. HEPA filters and vacuums are your best line of defense in eliminating mold spores. Non-HEPA filtered air cleaners and vacuums are the culprits- they keep the spores around by aerosolizing them and not removing them. Also, prevent mold growth in homes by eliminating sources of water – water incursions, adequate ventilation in bathrooms and general good hygiene. It is advisable to turn off the water to a home when leaving for more than 24 to 48 hours to prevent water incursions (water heaters or broken pipes).

Q. What are the most difficult indoor mold allergens to remove?

A. They are all the same in difficulty except that some species such as Penicillium and Aspergillus are more easily aerosolized and therefore more difficult to reduce to normal levels in the air.

Q. How would I go about testing if I had toxic molds in my home? Are there home tests I can run?

A. There are no home tests available. Potentially Toxic molds MUST be identified by a qualified laboratory, preferably an EMPAT (Environmental Microbiology Proficiency Analytical Testing) administered by AIHA which is currently revising this to an accreditation. Air testing should be done by a well qualified knowledgeable consultant, preferably with a good microbial background who uses an EMPAT laboratory for analysis.

Q. What are the best ways to get rid of mold in my home?

A. Bathrooms, window ledges, basements, kitchen all seem to be problematical. Water sources should be eliminated if possible – repair or improve ventilation and use dehumidifiers (eg. bathrooms and basements). Biocides are usually not necessary if moisture levels are adequately controlled. A Clorox type cleaner can effectively kill the mold on surfaces and can be used in bathrooms and other surfaces with the proper precautions (ventilation, gloves, etc.) and with an understanding that the mold will grow back if there is moisture in the future.

Q. Is an ozone machine an effective method of mold allergen removal?

A. No. Ozone levels cannot be obtained in indoor environments at sufficient levels to kill the spores. For one thing, those ozone levels would be very irritating to any inhabitants and secondly, the areas are too large and there is too much air exchange for the levels to reach fungitoxic levels. Also, the mold spores do not have to be alive to cause allergies or for mycotoxins to remain active. Thus ozone is not an effective method of control.

Q. I have heard about UV lights for air handlers or added to hepa filters, are they effective?

A. Not really. UV lights can kill the mold in the air handlers but as indicated before the spores don’t have to be alive to cause health effects. Also studies have indicated that indoor spore levels don’t change even though the levels of live spores in the air handler are reduced. Where UV lights do appear to have a use is in infectious situations (eg. hospital rooms) where the best method is referred to as an ‘upper room’. This basically involves placing UV lights in a shielded situation to prevent exposure to people but passively exposing air to the germicidal activity. The lights must be placed appropriately based on ventilation and air currents to ensure efficacious germicidal activity.