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Dr. Fix-It
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what are acceptable levels of Aspergillus/Penicillium spores

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what are acceptable levels of Aspergillus/Penicillium spores in a room?
Hi thanks for your question, I will evaluate it and respond with some logical and quite practical solutions for you in a timely manner. . .

Currently there is no government or industry standard as to what is deemed acceptable indoor levels of airborne fungal spores. However, it’s generally agreed that mould in indoor environments is a health hazard.

Please see the CDC site and below for more info -

Penicillium -

Penicillium is green bread mold but also grows in other places of the house, such as in an AC system, at leak areas, and flood areas where humidity has been elevated for an extended time, on shoes and furniture in a damp basement, etc.
Some people are allergic to Penicillium. Symptoms from mold exposure can be similar to those of Aspergillus. Under the microscope, spores from Penicillium are also spherical. You need to see the growth structure that produces the spores to distinguish them from the spores of Aspergillus. Penicillium growth structures appear brush-like, with strings of beads coming off the ends of the brushes.

Aspergillus -
Aspergillus is a very a common indoor mold that can be found on basement ceilings, at air conditioning coils, at leak areas, on the lower parts of foundation walls, on and under basement steps, on crawlspace ceiling joists and subflooring, at leaky roofs, in flooded areas where humidity has been elevated for an extended time, etc.
Under the general heading of the genus, Aspergillus, there are a couple of hundred species, such as Aspergillus fumigatus, Aspergillus niger, and Aspergillus versicolor. Some species give off mycotoxins, volatile organic compounds (VOC gases), and other byproducts that can be troublesome to susceptible individuals.
Mold symptoms can include headaches, trouble sleeping, itching, rashes, fatigue and other neurological complaints, and respiratory and asthmatic symptoms. One of the worst features of Aspergillus is that it can grow in human tissue. For people with weakened immune systems, this growth can eventually be fatal.
Under a microscope, Aspergillus looks like a flower that gives off strings of beads that are the spores. Spores are spherical, seen either individually under the microscope or present as a string of spores.
An interesting feature about Aspergillus is that it likes OSB (oriented strand board), which is a wood product used in new house construction. Many new homeowners who think they have a dry basement actually have a lot of Aspergillus growth on the basement ceilings and on the stairs to the basement.

See this link to find your local government agency contact -
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Customer: replied 6 years ago.
I already had the info you provided. I need to know if the levels of Aspergillus/Penicillium in my house are serious or not. A lab test showed a count 800 in one room and 1060 in another. Can't you tell me if these are worrisome or not?
The results of samples taken in your unique situation cannot be interpreted without physical inspection of the contaminated area or without considering the building’s characteristics and the factors that led to the present condition.

Also depends on how allergic the occupants are to the spores... So the lab that conducted to test should give risk analysis of the exposure level, if low or typical range for the area then may not be a concern but if is higher then what is expected then may have excessive moisture issue that needs to be address to control the spread of the mold. I have a ole place that is fine in summer but in winter when the heat is running will build moisture along the single pain glass and mold will grow and to control keep whole house fan running to have air circulation that keeps the glass dry and mold from growing.

Mold growth inside a home is never a good thing and if experiencing some of the symptoms listed for the type of mold identified above, then definitively should take steps to reduce the growth of further mold and reduce amount of exposed spores.