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High spore count but few sign of mold

MikeBlake | Posted in General Questions on

Hi, I have a 70 yr old farmhouse located in SW Coastal British Columbia.  The house was tested for mold 2 yrs ago in November.  I was renting it out with the tenants fully aware of the test results, however, they have just moved out and I am now hoping to solve the ‘problem’.  There were 3 air samples taken from the living areas and they each came back showing between 12000 and 18000 Aspergillus/Penicillium ct/m3.  Despite such a high spore count there is very little visible signs of mold and there is no musty odour in the house, except a slight smell in the laundry room, which is in an uninsulated cold room at the back of the house.  The bedroom nearest the laundry had the lowest reading at just over 12k.  I have opened up small sections of the walls in several areas and have not found any mold.  Before I start ripping out walls, is it likely that a count this high could be hidden? Shouldn’t I be able to at least smell it? Or could there be a problem with the accuracy of the air sampling or lab reading?  One issue that I have with the testing is that there was no outdoor sample taken due to high winds.  The house is surrounded by rainforest on three sides, is across the road from a hayfield and has compost piles, and chickens on the property.  Is it possible that these sources could produce test results this high in the house?  

Any thoughts are appreciated

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  1. Expert Member
    NICK KEENAN | | #1

    I'd get outdoor readings. I have a relative who is highly allergic to mold and she often feels it outdoors. She says the north side of a hill is worse than the south side.

  2. Expert Member


    I agree with DC. I'd bet the ambient levels in the rain forests here is very high, and your surroundings sound like a spore factory.

  3. MikeBlake | | #3

    I'd have the house retested tomorrow except I'd have to hire a company from Vancouver to do it which requires ferry travel to get here making it quite expensive. The last testing cost us $800 for four air samples ($100/sample) plus travel time and the inspection. So, I'd like to be confident that the house isn't the source of the problem. One possible flaw in my theory about the outdoors being the source, is that the crawlspace was also tested and its results differed from the living areas. The crawlspace showed 12000 Basidiospores ct./m3 with only 4000 Asperigillus. The interior rooms, in addition to the Aperigillus, tested between 2000 - 6000 Basidiospores. This difference between the two areas makes me question whether the outdoors could be the source. I also suspect that the spores aren't migrating up from the crawlspace. There isn't much info out there on spore count numbers and what they mean, Ive only found one source that said 2500 would be an acceptable count.
    The report I got back stated that the house has a 'major' mold problem and that I should not enter the house without a respirator.
    I have a lot more info on the condition of the house, but at this point I'm just wondering how likely it is that the house can be this contaminated and not show any signs.

  4. Debra_Ann | | #4

    I lived in several houses without any visible mold issues, but was made extremely ill from mold that was hidden inside the walls. We eventually identified some of the leaks - a plumbing vent that was leaking rain inside a wall for over 30 years, poor flashing between a chimney and house wall that cause a massive mold outbreak inside a wall, and a lack of kickout roof flashing that caused massive rot inside a wall 2 stories high.

    Most of this could not be smelled at all, except under certain circumstances (often after a major warmup in early spring). I take mold issues extremely seriously! It's incredibly frustrating that so much of it is invisible. Good luck.

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