More on the Interpretation of Mold Air Samples

Are you staring at the results of a mold test and struggling to figure out what it all means?  Let me try to help you.


The most common method used for mold air testing is uses a spore trap cassette. Because there is always a background amount of airborne mold spores, a key step in collecting air samples is to have a “reference” sample collected from the outdoor air at the time of the indoor testing. Since there are no guidelines on acceptable mold levels in the air, an outdoor sample is the best tool for interpreting the results of the indoor samples. Without the outdoor sample, you are limited in what you can gather from the results of the indoor samples.


There are various D.I.Y. air tests you can pick up at your local hardware store requiring you to place out a petri dish for several hours. Most of those tests are not very helpful in giving you any sort of usable data to evaluate the air in your home and as a general suggestion should be avoided.


Interpreting mold levels can be tricky. If you would like feedback on your mold air sampling results, please comment below and I will do my best to give any feedback I can in my free time. The views expressed in the blog post and comments are my own, and not necessarily those of Indoor Science. If you need a more immediate response regarding your results you can book a 30-minute phone consultation for $98 by clicking here.

101 thoughts on “More on the Interpretation of Mold Air Samples”

  1. Hello, I received the following mold reports and was hoping to get some insight into how to interpret the results. I suffer from seasonal allergies and am sensitive to mold and pollen. Should I be concerned about purchasing this house based on the attached results?


    1st sets of numbers = Control exterior
    2nd sets of numbers = basement interior
    raw ct. ; % red; spores/m3
    Ascospores 14 25 750 ; 0 0 0
    Basidiospores 98 25 5,200 ; 3 25 160
    Cladosporium 8 25 430 ; 2 25 110
    Curvularia 0 0 0 ; 1 100 13
    Epicoccum 0 0 0 ;2 100 27
    Ganoderma 2 25 110; 0 0 0
    Nigrospora 1 100 13; 0 0 0
    Other colorless
    Penicillium/Aspergillus types†
    Rusts 0 0 0 ; 4 100 53
    Smuts, Periconia, Myxomycetes
    Background debris (1-4+)†† : 2+ (outdoor) 3+ (indoor)
    Hyphal fragments/m3 : <13(outdoor) 27 (indoor)
    Pollen/m3: 27(outdoor) 27(indoor)
    Skin cells (1-4+): < 1+(outdoor) 3+ (indoor)
    Sample volume (liters): 75(outdoor) 75 (indoor)
    § TOTAL SPORES/m3 6,500 (outdoor) 360 (indoor)

    MoldSCORE™: Spore Trap Report
    Outdoor Sample: Control exterior
    raw count : spores/m3 : mold score
    Generally able to grow indoors*
    Alternaria ND ;< 13
    Bipolaris/Drechslera group ND; < 13
    Chaetomium ND ;< 13
    Cladosporium 8 ; 430
    Curvularia ND ;< 13
    Ganoderma 2 ;110
    Nigrospora 1 ;13
    Penicillium/Aspergillus types† ND; < 13
    Stachybotrys ND ;< 13
    Torula ND ;< 13

    Seldom found growing indoors**
    Ascospores 14; 750
    Basidiospores 98 ;5,200
    Rusts ND ;< 13
    Smuts, Periconia, Myxomycetes ND ;< 13
    Total 6,520

    Location:Basement Interior
    raw count : spores/m3
    Generally able to grow indoors*
    Alternaria ND ;< 13 ; 100
    Bipolaris/Drechslera group ND ;< 13; 100
    Chaetomium ND; < 13; 100
    Cladosporium 2 ;110; 105
    Curvularia 1; 13; 105
    Epicoccum 2; 27; 111
    Nigrospora ND ;< 13; 100
    Penicillium/Aspergillus types† ND ;< 13; 100
    Stachybotrys ND ;< 13; 100
    Torula ND; < 13; 100

    Seldom found growing indoors**
    Ascospores ND; < 13 ; 100
    Basidiospores 3; 160; 100
    Rusts 4 ;53; 121
    Smuts, Periconia, Myxomycetes ND ;< 13; 100
    Total 360(spores/m3);116(mold score)

    1. Stephanie,

      These numbers to me do not indicate elevated mold levels in the air of the basement. There is a small detail which is a little strange, the hyphal fragments in the basement are a little higher than I usually see indoors.

  2. I am a teacher who has had many health issues that I believe are related to mold in my portable classroom. Here are the results of the air quality test:
    Sample type: Air-O-Cell

    Analysis: Direct Microscopy; FALI Method IAQ 101; Modified ASTM D7391

    Volume: 75.0 L
    Ascospores – ND S/m3
    Basidiospores – 170 S/m3
    Cladosporium – 420 S/m3
    HYPHAL FRAGMENTS * – 35 S/m3
    Penicillium / Aspergillus – 770 S/m3
    Rusts/smuts/myxomycetes – 13 S/m3

    Inside w/AC on
    Ascospores – ND S/m3
    Basidiospores – ND S/m3
    Cladosporium – 8200 S/m3
    HYPHAL FRAGMENTS * – 490 S/m3
    Penicillium / Aspergillus – 380 S/m3
    Rusts/smuts/myxomycetes – 40 S/m3

    Can you help me interpret this??? I am very concerned as I was very sick for 7 months!!!
    Thank you!!!!

    1. Lu,

      In my opinion, I see that there is an elevated level of Cladosporium inside. This is a common mold type which can grow indoors in spaces with evevated humidity. I have also seen this type growing on A/C coils and drain pans.

  3. Hello,

    In the mold lab report, I saw Pen/ASP Group present on 51-75% of sample area.
    Sample media Type: Tape lift.

    The dry wall of the shower may have a leakage behind. The ceiling of the shower is easily to get mold. The ceilings mold are removed so no sample. This sample is got by opening a small part of the dry wall and taped the area. Is the Pen/ASP mold behind the dry wall the cause of the mold often appearing in the ceiling?
    The Pen/asp are currently only found behind the drywall. Will it penetrate thru the drywall and present in the shower room?

    Thank you

    1. Lisa,

      Microscopically Pen/Asp appears like a field of dandelion seed heads. When they are disturbed the spores release into the air, and Pen/Asp have a lot of spores! If the materials are chronically damp then it is possible to have mold growth on both sides, the extent of the growth is dependent on the extent of the moisture in the material. The only way to see if the mold is affecting the air quality is to have air samples collected.

  4. Thank you Dylan,

    Does this report ” Pen/ASP Group present on 51-75% of sample area” means I have toxin mold which impacts health? Do you know where I can find link on what human impact will Pen/ASP have?
    Another question, not all ASP/Pen are toxic. Which lab can identify the species of the ASP/Pen on my dry wall, and what the cost is? I want to find out if they are toxic.
    Thank you


    1. Lisa,

      I am not a healthcare professional, so I can not comment on possible health effects. All we can take away from that result is that there is Asp/Pen growing on the surface. Most commercial environmental microbiology labs can speciate Asp/Pen, some national labs are EMSL, EMLab P&K.

      The purpose of this blog post is to provide interpretation of air sampling lab reports, so I just ask that comments please stick to this theme.

  5. Thank you Dylan. I don’t know why my inspector didn’t take a air sample of the bathroom, but just taped a sample directly on the mold from the opened bathroom dry wall. I really want to find out if the air is contaminated since the mold is behind the dry wall.
    I called the lab , IMS Laboratory, which tested the sample, to check if they can speciate ASP/PEN. But they just told me to talk with my inspector on it.
    I am calling EMSL and the other labs you recommended to find out who can do it and may do another test again.

  6. Hi Dylan I could really use your help. I live in a relatively new building…its about 7 yrs old. For about 1 year I’ve smelt mold/ must in my son’s bedroom. I initially attributed it to him being a teenager but the smell got stronger and stronger. I investigated and found mold growing on clothes in his closet, mold growing on the side of his bed, his desk, books on shelf, head phones and just randomly throughout his room. I brought it to management’s attention and they dismissed it bc they couldn’t find a source of mold or water. They tried to blame it on me for not opening windows or ventilating my unit (which I do every day). My family started getting sick so I decided to hire a professional to do a spore trap report and I got the following results.

    Control/ outside: Penicillium/ Aspergillus = 75 spores per cubic meter. Raw Count 3

    Bathroom: Pen/ Asp = 18,000 spores per cubic meter. Raw Count 450

    Master Bd Rm: Pen/ Asp = 12,600 spores per cubic meter. Raw Count 315

    Guest Bd Rm: pen/ asp = 73,000 spores per cubic meter. Raw Count 1818

    Living Room: pen/ asp = 9,000 spores per cubic meter. Raw Count 235.

    Living Room: Basidiospores = 2600 spore per cubic meter. Raw 65

    Management believes I am at fault for the elevated mold levels bc they cannot find water intrusion. Is it possible we are doing something to cause mold growth? We open windows every day and also have a double heppa air purifier. I would appreciate your expertise here.

    Also, we live in San Francisco, CA so we don’t have AC and the humidity level in our unit was 68 % and temp 78 degrees when the testing was done( we had a heatwave). On average the humidity is 62% and temp 74 degrees indoors.

    1. Jessa,

      The results in your comment show elevated levels of Asp/Pen. Finding out what is causing the mold to grow is much more difficult than just collecting the air samples. Since the mold was found growing on items in the room, and not just the building materials, that to me is a sign of some sort of humidity issue. Now, this could be hand in hand with water intrusion, I can not determine that. I would recommend hiring a mold inspector that will do more than just air samples to figure out the issue. It would be good to have an infrared and moisture meter scan done either during or directly after heavy rain. I would also suggest monitoring the humidity levels in the rooms, and if the humidity is consistently over 60% it may be worth running dehumidifiers.

  7. Hello,

    I’m selling my house in Northern IL and have been asked by the buyers for a mold remediation credit for high aspergillus in the basement bathroom. There is no visible mold and a different mold inspector I had come out couldn’t find any moisture at all with a handheld detector. The drywall in a storage area behind that bathroom did get wet once 6 years ago. The humidity inside was 48% according to the report.

    Could you give me your interpretation of these lab results? The only indoor sample was taken right by the toilet.

    Location Outside Basement
    Detection Limit (spores/m3) 40 40
    Hyphal Fragments 2 80 3 120
    Pollen 3 120
    Spore Trap Used M5 M5

    raw ct. spores/m3 % raw ct. spores/m3 %

    Alternaria 3 120 <1
    Ascospores 14 560 4 1 40 1
    Basidiospores 33 1320 9 9 360 13
    Cladosporium 273 10900 76 16 640 24
    Epicoccum 2 80 <1
    Penicillium/Aspergillus 5 200 1 40 1600 59
    Rusts 27 1080 8
    Smuts/Periconia/Myxomy 1 40 <1 2 80 3
    Colorless/Other Brown
    Background debris (1-5) 3 3
    Sample Volume(liters) 25 25

    Raw ct Spores/m3 Raw ct Spores/m3
    TOTAL SPORES/M3 358 14300 68 2720

    1. Maria,

      Yes, I would say these results show a slightly elevated level of Aspergillus/Penicillium inside the basement. However I do also notice that these samples were collected for a shorter time than most, the industry standard for the sample volume is 75L and these samples only collected 25L. We can see elevated levels of Asp/Pen in basements with no visible mold or water damage sometimes due to chronic high humidity. It is important to remember that the inspector’s readings only show conditions at that exact moment, so just because they did not find moisture and the humidity was acceptable during the inspection that does not mean that if outside conditions are different that they would get the same results.

  8. Thank you! I understand that it’s only slightly elevated but we will probably let them have the credit.

    What you said about moisture presence being partially dependent upon outside conditions makes sense.

    It’s very generous of you to share your expertise on the internet. Thanks again!

  9. Hi Dylan!

    We’re recovering after Harvey flooding down here in Houston. Thankfully we only had 8″ or so of water in the home we were renovating and were able to get in pretty quickly and tear out all of the sheetrock. We just had our fist post-remediation mold test and we have elevated levels of Chaetomium. We had two indoor readings – this was the higher of the two.

    Particle Identification / Raw Count (Count/m³) / % of Total
    Alternaria – – –
    Ascospores 1 / 200 / 6.1
    Aspergillus/Penicillium 10 / 2200 / 66.7
    Basidiospores 3 / 700 / 21.2
    Bipolaris++ – – –
    Chaetomium 1 / 200 / 6.1

    Our inspector was citing the elevation likely originating from one area behind a built-in cabinet – which we plan to remediate further at his suggestion. We also had two large holes in the slab from where we were doing under slab plumbing and I suspect those were also contributing to the readings. Those are now being filled in with concrete. Otherwise, the home is bare bones so I’m at a loss where the readings are coming from.

    Can you help me understand what an acceptable level of Chaetomium is?

    Any tips to tackle Chaetomium remediation?


    1. Eleanor,

      Chaetomium mold is a type that is considered a water damage indicator, and it is not found in the outdoor air, so therefore any amount of Chaetomium is likely to be considered “elevated” by an inspector. My opinion the numbers on your test is likely just residual spores in the air from the remediation, and if you have the remediation company run the air scrubbers for a few more days it should take care of it. Another possibility is that there might be some settled construction dust which could be holding residual spores. If the home has visible work dust I would have them vacuum them up. I doubt there is missed growth anywhere in the house, because as you say it is bare bones, this is likely just leftover spores in the air from the tear out.

  10. Hi: we are currently in the process of buying a new home. As part of our home inspection, we had an air quality test conducted. During the inspection, there was no visible mold or evidence of moisture/mold found anywhere in the home. However, the AQT came back with positive results for stachybotry. Raw Count: 4, read: 100%, spores m/3: 53. Since this test, the selller had a mold assessor come to the home for a visual mold inspection- he was able to find one small area of mold (which wasn’t swabbed), and a water stain under the kitchen sink. Still not reassured, we (us & seller mutually) brought in another 3rd party remediation company that looked behind walls using a camera. He only looked in areas common for moisture problems: finished basement, attic, near plumbing, etc. they found a couple sources of a potential problem, but when swabbed none were positive for staychbotry.
    His results were:
    Aspergillus: spore estimate = moderate; mycelial estimate: many
    Mycelium: spore estimate = ND; mycelial estimate = many
    Curlvularia: spore estimate = ND; mycelial estimate= rare
    Myxomycetes: spies estimate = ND; mycelial estimate = rare.
    I have a 1yr old baby, and I am pregnant with baby #2. I am very concerned that we are unable to locate the source of the stachybotry. The seller seems to believe that it may have been carried from the outdoors to the indoors on someone’s shoes (or similar). Is this possible? Should I be alarmed?

    Any advise or information you could provide would be greatly appreciated- thank you in advance!

    Thank you,
    Nervous mommy

    1. Whenever we see Stachybotrys in air samples that is a warning to us. Stachybotrys is not found in outdoor air samples very often and is an indicator of water damage inside the home. You could have another air sample collected to see if that Stachybotrys level was just an anomaly. If Stachy shows up on that air sample I would say that strongly supports some sort of indoor growth.

      1. Thank you very much! One other question, if you don’t mind. Based on the stachybotry results, are you able to determine if the stachybotry problem seems wide spread or more of an isolated problem? Is that a high reading? And do you believe stachybotry to be dangerous to human health?

        Thanks so much again!

  11. Hi there. We had a water leak in our guest bedroom (interior wall). The home builder removed/replaced wall and part of flooring but we didn’t use mold remediation company, so I am little concerned. Our recent mold test indicated penicillium/Aspergillus in a higher level than all the other types of mold but lower than outdoor levels. Would something like an air scrubber resolve this? Also, should I re-test after a certain period of time, to ensure levels are dropping? If so, what time frame do you recommend?

    Thank you – Alicia

    Sample Type/Volume: Z5 -25L (Spore Trap)

    Particle Identification / Raw Count (Count/m³) / % of Total

    Cladosporium: 4/ 160 / 9
    Other Ascospores: 1/ 40 / 2
    Other Basidiospores: 5/ 200 / 11
    Penicillium/Aspergillus: 24/ 960 / 53
    Smuts, myxomycetes: 11/ 440/ 24
    Total Spores: Count = 45/ 1800 / 100

    Guest Room:
    Cladosporium: 3 / 120 / 13
    Other Ascospores: – – –
    Other Basidiospores: 2/ 80/ 8
    Penicillium/Aspergillus: 18/ 720 / 75
    Smuts, myxomycetes: 1/ 40 / 4
    Total Spores: Count = 24/ 960/ 100

    1. Unless you still see visible mold growth around, I would say these air samples are acceptable. If you were still concerned with the numbers you could run an air scrubber to clear the airborne mold from the air. You could retest after running the air scrubber for a few days, just make sure the scrubber is turned off before testing. I would also suggest running the sample for at least 75L, as opposed to the 25L that was done for the above testing.

  12. I have recently been affected by Harvey but the rental I was living in with my kids showed signs of mold 2 weeks prior from substantial wind driven rain… I have a copy of the air quality report and would like your opinion…. I have been to the doctor recently and three is concern about the effects on my lungs and body in general… would you be able to help read these air report?

  13. I have recently put a contract on a lake house but these were the mold results and I don’t understand them. Do these levels seem like an issue to you? Please help.
    AB Identification Number: EH092717-14-1 EH092717-14-2
    Sample Identification Number: 2157808 2157843
    Date Collected: Sep/26/2017 Sep/26/2017
    Description: Basement Outside Air
    Sample Type: Spore Trap Spore Trap
    Sample Condition: Intact Intact
    Volume/Area Sampled: 25 L 25 L
    Reporting Limit: 40 40
    Spore Identifications Raw Count Spores/m3 Raw Count Spores/m3
    Acremonium-like ND BDL ND BDL
    Alternaria 1 40 ND BDL
    Arthrinium ND BDL ND BDL
    Aspergillus ND BDL ND BDL
    Aureobasidium ND BDL ND BDL
    Botrytis ND BDL ND BDL
    Cercospora-like ND BDL ND BDL
    Chaetomium ND BDL ND BDL
    Cladosporium 116 4640 1596 63840
    Coprinus ND BDL ND BDL
    Curvularia 1 40 2 80
    Drechslera/Bipolaris Helminthosporium/Exserohilum ND BDL ND BDL
    Epicoccum ND BDL ND BDL
    Fusarium ND BDL ND BDL
    Ganoderma ND BDL ND BDL
    Memnoniella ND BDL ND BDL
    Nigrospora ND BDL ND BDL
    Penicillium ND BDL ND BDL
    Penicillium / Aspergillus – like 3052 122080 43 1720
    Pithomyces 1 40 ND BDL
    Scopulariopsis-like ND BDL ND BDL
    Spegazzinia ND BDL ND BDL
    Stachybotrys ND BDL ND BDL
    Tetraploa ND BDL ND BDL
    Torula ND BDL ND BDL
    Trichoderma-like ND BDL ND BDL
    Ulocladium ND BDL ND BDL
    Ascomycetes-unspecified 22 880 19 760
    Basidiomycetes-unspecified 24 960 316 12640
    Hyphomycetes-unspecified ND BDL ND BDL
    Zygomycetes-unspecified ND BDL ND BDL
    Myxomycetes/Perconia/Smuts/Rusts ND BDL ND BDL
    Miscellaneous structures
            Hyphae Present Present
            Clamydospores ND BDL ND BDL
            Perithecia ND BDL ND BDL
            Sclerotia ND BDL ND BDL
    Background Particulate Density Medium Medium
    Total Spore Count 3217 128680 1976 79040

    1. These results show a major elevation of Aspergillus/Penicillium indoors. The indoor sample shows an elevation of almost 100x, strong evidence that there is some mold growth and moisture issues in the home.

  14. Hello Dylan-
    I’m another Harvey victim, down here in Houston. We had water intrusion through our weep holes and under the floor. All flooring has been removed and most built-ins, EXCEPT kitchen cabinets. We just got results from the air sampling. My concerns are the Cladosporium, Penicillium/Aspergillus, and Stachybotrys levels inside.

    Outdoor control: (raw ct./spores m3/%)
    Cladosporium 16 / 640 / 20
    Pen/Asp 15 / 600/ 19
    Stachybotrys 0

    Cladosporium 2 / 8 / 7
    Pen/Asp 26 / 1040 / 90
    Stachybotrys 1 / 40 / 3

    Prior to testing, I cleaned all surfaces with antimicrobial cleaner, sprayed visible mold with disinfectant, and ran an air scrubber w/HEPA filter for 72 hours. The walls behind the refrigerator and dishwasher (both are on either side of the kitchen cabinets) were dry by the moisture sensor readings, and no visible mold.

    Our questions now are
    1) are these dangerous levels of mold?
    2) without any visible signs of mold, should we deduce that the mold source is behind the cabinets?

    Many, many thanks for your input.

    1. The single spore of Stachybotrys is not a statistically relevant result, so I can not say one way or another in relation to that. THe Aspergillus/Penicillium levels insde are slightly high, but it is not as high as you would see in a home with major mold issues. It is likely the small amounts of mold you see growning in the home are what is contributing to the levels in the air. I have no concern over the Cladosporium levels indoors.

  15. We’re trying to interpret an ERMI analysis with results in spores eq/mg dust on a house we are considering purchasing. No outdoor samples were collected. A 5 mg sample was collected with a vacuum on carpet in two rooms from the second and third floors (not the basement). Here are the results for species that were not “ND” from EPA 36 Species Identification Group 1:

    Aspergillus penicillioides: 48
    Aspergillus restrictus: 12
    Aspergillus versicolor: 45
    Eurotium (A.) amstelodami: 55
    Aureobasidium pullulans: 102
    Cladosporium sphaerospermum: 19
    Paecilomyces variotii: 9
    Penicillium spinulosum: 16
    Penicillium variabile: 2
    Wallemia sebi: 23

    The ERMI Value = 2.6
    ERMI Interpretation = Level 3, which states Relative Moldiness. Further investigation needed to determine if sources of mold exists.

    Group 2 sum of the logs indicated low relative moldiness.

    Any advice on how to remediate, if needed? There are no visible signs of water/mold. The inspector, using a thermal camera found no signs of moisture but he recommended adding a dehumidifier to the basement, which is 90% finished. The house is two years old.

    1. Unfortunately, an ERMI test is not suited to answer the questions you have. All we can do to interpret the results is what it says in the report, that there may be indoor mold/moisture issues but further investigation is needed. An ERMI test looks at the likelihood a property has had water damage and mold growth at some point in the past, it does not evaluate the current conditions of the space. ERMI testing cannot be used to determine if remediation is needed, you need a good visual assessment and moisture testing.

  16. HI Dylan,
    Thanks so much for helping out and offering insight into these tests. I own a rental unit (I used to live in it). Some of the ladies who now live in the unit asked a company to do an Air-O-Cell / 75.0L spore collection test. They presented this document to us as evidence that our house has mold issues and are demanding a reduction in rent as well as an early termination of the lease. We are obviously seeking legal assistance for that. However, we have NO IDEA what these levels even mean. We have a certified Class A builder who specializes in water remediation doing all work. He found (2) spaces in what is called the front room – which has a sump pump due to previous water penetration – that has water infiltration from the foundation. He found NO foundation issues in the bedroom but did find that the tenants were not using the dehumidifier or using the bathroom exhaust fan during and after showers. It was his opinion that the front room elevated results were because of foundation issues and he has repaired the foundation by excavating around the area. He found nothing to repair in the basement master bedroom. These are the results of the test:

    Master BEDROOM:
    fungal types identified / raw count / spores/ m3 / % of total:

    Peniscillium/Aspergillus 152 / 2,022 / 94%
    Ascospores 2 / 27 / 1%
    Basidiospores 6 / 80 / 3%
    Total Spore Count 160 /2,129 / 100%

    Front room:
    Penicillium/Aspergillus 536 / 7,219 / 95%
    Acospores 1 / 13 / <1%
    Basidiospores 11/ 146 / 1%
    Cladosporium 11/ 146 / 1%
    Epicoccum 1/ 13 / <1%
    Penicillium/Aspergillus —/ —–/ —–
    Polythrincium —/ —–/ —–

    Penicillium/Aspergillus —/ —–/ —–
    Acospores 16 / 213 / 10%
    Basidiospores 78/ 1,037/ 52%
    Cladosporium 47/ 625 / 31%
    Epicoccum —/ —–/ —–
    Penicillium/Aspergillus 6 / 80/ 4%
    Polythrincium 2 / 27 / 1%
    TOTAL 149/ 1,982 / 100%

    Penicillium/Aspergillus —/ —–/ —–
    Acospores 7 / 93 / 17%
    Basidiospores 16/ 213/ 39%
    Cladosporium 8 / 106 / 19%
    Epicoccum —/ —–/ —–
    Penicillium/Aspergillus 10 / 133/ 24%
    Polythrincium —/ —–/ —–
    TOTAL 41/ 545 / 100%

    Specifically, I'm trying to understand what do these numbers MEAN? Does this mean that there is a huge problem of mold that cannot ever be removed despite my contractor removing drywall (with no visible evidence of any mold damage – simply some dampness associated with a water leak) and no seen or visible mold issues anywhere?

    If it helps, on the first day of the repair work, he measured humidity in both rooms that have issues. Room #1 – the master bedroom, which is mostly below grade level, measured at 52% humidity with no dehumidifiers being run at all. After dehumidifiers being run for only 8 hours, the humidity level measured at 38%.

    In the front room, where there was a sump pump and known water infiltration (hence the sump pump), the humdity measured at 56% before work began (with no dehumidifiers) and measures at 42% now that work has been completed (with no dehumidifiers).

    I thank you in advance for your kind assistance.

    1. All mold issues can be remediated to a pre-loss state, so if the work is done correctly and moisture issues are identified and solved the mold from this issue will not persist. There is an elevation in the bedroom and front room of Aspergillus/Penicillium. The bedroom levels are slightly higher than what we can see in the outdoor air from time to time, the front room is higher but not off the charts relative to how high these numbers can be in homes with major issues.

  17. Hi Dylan,

    Thank you for helping people interpret the data. We recently had a test done and here are the findings. Any input from you would be really well received. Thanks!

    Sample Type/Volume: Allergenco D 75L

    Particle Identification / Raw Count (Count/m³) / % of Total

    Alternaria 16/213/3%
    Ascospores 32/427/6%
    Aspergillus/Pen 104/1387/19%
    Basidiospores 3/40/ <1%
    Cladosporium 355/4733/64%
    Curvularia 1/13/<1%
    Epicoccum 6/80/1%
    Ganoderma 4/53/<1
    Nigrospora 2/27<1
    Pithomyces 5/67/<1
    Rust 9/120/2%
    Smut/Myxo/Per 15/200/3%
    Total Spores 552/7360

    Ascospores 3/40/<1
    Aspergillus/Pen 317/4227/81%
    Basidiospores 3/40/ <1%
    Cladosporium 62/827/16%
    Ganoderma 3/40/<1
    Pithomyces 1/13/<1

    Total Spores 389/5187

    Ascospores 22/293/6%
    Aspergillus/Pen 95/1267/26%
    Basidiospores 3/40/ <1%
    Cladosporium 234/3120/65%
    Ganoderma 3/40/<1%
    Smut/Myxo/Per 4/53/1%

    Total Spores 361/4813

    1. Sarah,

      I am seeing an elevation of Aspergillus/Penicillium in the basement sample. We can see this type elevated in basements frequently and would suggest monitoring humidity levels in the basement if you do not have signs of visible mold or a history of water issues.

  18. Hi,
    Hoping you can help interpret these findings. We had a leak from our bedroom window, cleaned up the same day, removed and replaced carpet. No signs of visible mold. These samples were taken the week after.
    Thanks in advance!
    Bedroom sample:
    Aspergillus/Penicillium 71 sp/m3
    Cladpsoriurm 329 sp/m3
    Smuts/Myoxomycete/Periconie/Rust 3082 sp/m3
    Strachybotrys 71 sp/m3

    Outdoor sample:
    Aspergillus/Penicillium 165 sp/m3
    Cladpsoriurm 1035 sp/m3
    Smuts/Myoxomycete/Periconie/Rust 6235 sp/m3
    Strachybotrys 24 sp/m3

    1. Corinne,

      Typically if you take care of wet materials in 24-48 hours you minimize the risk of mold growth. These results look good to me for the indoor space.

  19. Ian, please help… I am a young mother who developed sudden health problems (severe joint aches that migrate) that correlate with purchasing anolder home that was uninhabited for several years in the north east part of the country. The unfinished basement show signs of moisture and has a strong musk and we have been trying to clean it for the past 1.5 years. We got rid of anything that had the appearance of mold. My symptoms have never gotten better despite a clean bill of health with a doctor and specialist. My instinct tells me that it’s the house and I am making myself sick thinking that I’m leaving and I’m varmint that’s poisoning me or my children. I am young and prior to this was an athlete and healthy. I am at my wits end with feeling discomfort all the time. I recently had a mold expert who seemed very knowledgeable and he sent me our lab results tonight which did not come with the explanation. Please note that the children and the master bedroom is on the second floor. Aspergillosis/pen 2000 count/m3 in kids room and 27,800count/m3 in basement

    1. Ashley,

      I can’t make too many conclusions with what you provided. I will say that the 27,800 in the basement seems elevated, but without an outdoor sample I do not have any context on how high it might be.

  20. Hi, Dylan!

    I just received these results on a potential new home with a note that the levels are not elevated. I would love to hear your thoughts as well, as I have long-term issues with asthma.

    Fungal Spore Type Spore Count Spore Count/m³ Spore Count Spore Count/m³ Spore Count Spore Count/m³
    Alternaria — — 1 13 — —
    Arthrinium — — — — — —
    Ascospores 8 107 — — — —
    — — — — — —
    Basidiospores 4 53 — — — —
    Bipolaris/Dreschlera — — — — — —
    Chaetomium — — — — — —
    Cladosporium 8 107 10 133 5 67
    Curvularia — — — — — —
    Epicoccum — — — — — —
    Fusarium — — — — — —
    Memnoniella — — — — — —
    Nigrospora — — — — — —
    Oidium/Peronospora — — — — — —
    Pithomyces — — — — — —
    Polythrincium — — — — — —
    Rhizopus/Mucor — — — — — —
    91 1210 18 240 27 360
    Spegazzinia — — — — — —
    Stachybotrys — — 1 13 — —
    Stemphylium — — — — — —
    Torula — — — — — —
    Ulocladium — — — — — —
    Unidentified Mitospores — — — — — —
    Total Fungal Spores 111 1480 30 400 32 427

    1. Everything seems normal in these results, however a slight yellow flag with the detection of 1 spore of Stachybotrys. It is likely this result is just an anomaly since it is very low, but Stachybotrys is a water damage indicator type.

  21. Hi and thanks in advance for any help you can provide!
    I had my daughter’s dorm room tested after she had some severe medical issues.
    The air tests didn’t seem too bad. The outside air had much higher levels than inside. For example, aspergillus/penicillium inside was 110 spores/m3 with a raw count of 8 and 100% read. Outside was 350 spores/m3 with a raw count of 26 and 100% read.
    Total spores inside were 270 spores/m3.
    The other part of the testing was swab and dust sampling.
    Swabs of the back interior wall in which the paint was bubbling and peeling off the concrete blocks show 1600 spores/unit with a raw count of 3 of chaetomium; and 98000 spores/unit with raw count of 94 of brown hyphae ID unknown.
    Finally, with dust sampling we found 2.724 ppb of ochratoxin A (present if greater than 2 ppb); and 2 spores/mL of rhizopus stolonifer.
    Is any of this something to be concerned about?

    1. The swab showing Chaetomium is a yellow flag, and if you were to open up the wall you may find mold growth inside the wall. The air samples seem okay, and the lack of Chaetomium in the air sample is a good sign. For the mycotoxin testing, there is not a lot of information on interpreting what is acceptable levels, so unfortunately I can not add anything for the dust sample.

  22. Thanks for doing this Dylan, we appreciate it more than you can know.
    Just closed on a house, seller lied on disclosure form about water damage. Just got this done, thoughts?

    Location: Outside

    Exposure: 15.00 l/min. for 5.00 min.
    Reporting Limit: 53 Spores/cu. m

    Sample Identification Raw Count Spores/cu. m Percent(%)
    – Fungi –
    Cladosporium 113 6,030 45.76%
    Basidiospores 95 5,070 38.47%
    Ganoderma 15 800 6.07%
    Epicoccum nigrum 9 480 3.64%
    Ascospores 7 373 2.83%
    Alternaria 4 213 1.62%
    Cercospora group 1 53 0.40%
    Pen/Asp group 1 53 0.40%
    Rust 1 53 0.40%
    Smuts/Periconia/Myxomycetes 1 53 0.40%
    Total Fungi 247 13,200 100.00%

    – Other –
    Hyphal Fragment 2 107 100.00%
    Background Item Level
    Dust / Debris Very Low
    Hyphal Fragments Very Low
    Opaque Particles Very Low

    Location: Basement

    Medium Type: AllergencoD

    Sample Identification Raw Count Spores/cu. m Percent(%)

    – Fungi –
    Pen/Asp group 74 3,950 45.16%
    Cladosporium 42 2,240 25.61%
    Basidiospores 37 1,970 22.52%
    Ganoderma 6 320 3.66%
    Ascospores 3 160 1.83%
    Epicoccum nigrum 1 53 0.61%
    Stachybotrys 1 53 0.61%
    Total Fungi 164 8,750 100.00%

    – Other –
    Hyphal Fragment 2 107 100.00%
    Background Item Level
    Dust / Debris Medium
    Hyphal Fragments Very Low
    Opaque Particles Very Low

    Location: Living Room

    Sample Identification Raw Count Spores/cu. m Percent(%)

    – Fungi –
    Cladosporium 77 4,110 46.43%
    Basidiospores 52 2,770 31.29%
    Ganoderma 10 533 6.02%
    Pen/Asp group 8 427 4.82%
    Ascospores 7 373 4.21%
    Epicoccum nigrum 5 267 3.02%
    Rust 3 160 1.81%
    Alternaria 1 53 0.60%
    Cercospora group 1 53 0.60%
    Curvularia 1 53 0.60%
    Nigrospora 1 53 0.60%
    Total Fungi 166 8,850 100.00%

    – Other –
    Hyphal Fragment 2 107 100.00%
    Background Item Level
    Dust / Debris Low
    Hyphal Fragments Very Low
    Opaque Particles Very Low

    1. With these samples, there is an elevated level of Pen/Asp in the indoor samples. The levels are higher in the basement, this is a type we see elevated in basements a lot. We can see elevated pen/asp with a range of moisture issues, so it could be from leaks, humidity, issues, flooding, ect.

  23. I had a mold inspector come to view a condo i was looking to purchase. He found no visible signs of mold nor with one of those wall metering things. An outdoor and indoor sample (air trap method) of the attic area where the hvac and water heater are located. Elevated levels of penicilium/aspergilus (273/m3 outside to 3820 inside) and stachbotrys (0 to 624) came back.

    The inspector had just come from a remediation project. Is it possible the levels were so high because he was just in a contaminated area and might have had mold on him from that project thereby affecting the test he was performing?

    1. You are correct that it is possible for a contractor to affect a sample if they have been in moldy areas, but the levels on the samples you sent are much higher than what I would expect to see if the mold was on the clothes/equipment. However, it is not standard practice to collect an air sample in an attic, in many climates attics are naturally ventilated, so this can result in high levels of settled spores in attic dust that can get reintroduced to the air and create false positive readings. Since the inspector did not find visible mold in the area I would put more weight on that than the air samples in the attic.

  24. Good morning:

    Thank you for this great site. I just bought a house and did a mold/moisture test. We just installed new roof. Prior roof was leaking, and there are water stains on ceilings in some areas, though moisture detector did not detect active moisture in those portions. The only areas with active moisture are efficiency and family room near door/baseboard. Can you please provide me your opinion on the following mold test results:

    Volume Sampled of each: 75L

    Raw Count- 9
    Count/m3- 120
    %- 60
    Raw Count- 4
    Count/m3- 53
    %- 27
    Raw Count- 1
    Count/m3- 13
    %- 7
    Raw Count- 1
    Count/m3- 13
    %- 7
    Total Spores:
    Raw Count- 15
    Count/m3- 200
    Hyphal Fragments- N/A

    Living/Family Rooms:
    Raw Count- 8
    Count/m3- 107
    %- 80
    Raw Count- 1
    Count/m3- 13
    %- 10
    Raw Count- 1
    Count/m3- 13
    %- 10
    Total Spores:
    Raw Count- 10
    Count/m3- 133
    Hyphal Fragments:
    Raw Count- 1
    Count/m3- 13

    Master Bedroom:
    Raw Count- 5
    Count/m3- 67
    %- 4
    Raw Count- 11
    Count/m3- 147
    %- 8
    Raw Count- 57
    Count/m3- 760
    %- 42
    Raw Count- 9
    Count/m3- 120
    %- 7
    Raw Count- 21
    Count/m3- 280
    %- 16
    Raw Count- 14
    Count/m3- 187
    %- 10
    Raw Count- 7
    Count/m3- 93
    %- 5
    Raw Count- 2
    Count/m3- 27
    %- 1
    Raw Count- 9
    Count/m3- 120
    %- 7
    Total Spores:
    Raw Count- 135
    Count/m3- 1800
    Hyphal Fragments:
    Raw Count- 2
    Count/m3- 27

    Raw Count- 7
    Count/m3- 93
    %- 100
    Total Spores:
    Raw Count- 7
    Count/m3- 93
    Hyphal Fragments:
    Raw Count- 1
    Count/m3- 13

    Thank you!

    1. Jorge,

      I see an elevated level of Asp/Pen and Cladosporium in the bedroom samples. These levels are slightly elevated, as we can see levels higher than this in the outdoor air from time to time. The Stachybotrys levels in the efficiency sample is concerning to me, this to me shows that there is likely some sort of indoor growth in this area.

  25. Dylan, we just moved into a rental house with some previous water damage (obvious staining on walls). We decided to have the air tested and found chaetomium in most rooms (low levels, all under 150), and even Stachybotrys (2 rooms with under 10 and master bathroom with 80 count). Penicillium and aspergillus are all under 200. There are some water stains on the walls. The landlord has agreed to fix the roof but not going to do anything about damaged drywall other than repainting it. Some areas are soft and they’ll cut them out. Those areas that are hard and not warped will be just painted over with oil based primer. Will that be enough? With low counts in air samples , do we need to insist on mold remediation or should we just take a “wait and see if it comes back after the roof repair” approach?

    1. Any level of Chaetomium and Stachybotrys in air samples is an indication of indoor mold growth. It is likely that there is some level of mold growth inside those wall cavities that have evidence of moisture issues. Repairing the roof might address the moisture and stop future issues from coming up, however, it will not remove what is already present. All affected materials should be removed by a qualified mold remediation professional in my opinion.

  26. Sorry, I was concentrating so hard to make the numbers look presentable that I forgot to put the backstory haha.
    In March the former owner of the house had a hot water heater break & flood two small rooms. I had numerous companies come out giving different opinions on what needs to come up, like drywall and flooring vs just carpet (not the laminates or cedar closet walls) and just wipe it w/ anti mold solution, run dehumidifier and get Heppa filter.
    But there is no visible mold, and half the people had positive moisture readings and the other half didn’t. Only one person used an IR cam and didn’t see any moisture either.

    Thanks again,

  27. I ripped up some carpet. Nevermind. It’s soaked underneath. :(
    Thanks though :)
    This is a wonderful service you’re providing.

  28. Hi Dylan,

    We recently had some flooding in our neighborhood from hurricane Irma. We we’re lucky and there was only a little bit of flooding in our place. However in weeks to follow the moisture in the house was noticable. We had an inspection and the following lab report was provided; recommending remediation. I am pregnant and I’m wondering how safe these levels are for a newborn upstairs and how long remediation should/would take. Also any opinion on how effective the Dyson airblade purifiers are? Thanks!
    Raw ct – spores/m3 – %
    Alternaria: -null-/2ct-80m-2%/null
    Ascospores: 30ct-750m-9%/7ct-280m3-7%/3ct-120m3-8%
    Basidiospores: 54ct-1350m3-17%/4ct-1603-4%/1ct-40m3-3%
    Cladosporium: 162ct-4050m3-50%/13ct-523-12%/4ct-160m3-11%
    Curvularia: 15ct-375m3-5%/12ct-480m3-11%/1ct-40m3/3%
    Penicillium/Aspergillus: 47ct-1180m3-15%/69ct-2760m3-64%/27ct-1080m3-75%
    This last one is a little concerning.
    I really appreciate your time.

    1. You are correct in that the Pen/Asp levels in the home are slightly high. We can see Asp/Pen levels that high outdoors on occasion, and in homes with major issues we can see these levels 10,000+. The levels are not very high, so remediation shouldn’t be a very big ordeal, however, I have not seen the property so I do not know what exactly needs to be addressed. I am not a licensed health professional so I can not comment on “safe” levels for health. I don’t have any experience with the Dyson product, all I can say is that it advertises to filter particles at HEPA levels, which for a consumer purifier as good as you can expect.

  29. Our home flooded during Hurricane Harvey. Water levels reached 2-3 feet in the house and stayed in the water for about 48 hours. Demo was done within 4 days, drywall was cut to 6 feet high. We had a professional company come in and do the dry-out with industrial blowers & dehumidifiers until the moisture readings were below 17 throughout the house. They treated all exposed wooden beams twice with moldicide.
    We are just about to begin the re-build process and got a mold test last week, just to make sure everything was ok. We were shocked when we received the results this morning and it said we had “Elevated Mold Conditions” and “Mold Remediation Recommended.”
    I will do my best to present the numbers as they are in the report. Please tell me if I should be tremendously concerned, or if this might be fairly simple to remediate.

    Thank you!

    Master Bedroom
    Basidiospores 2 – 80 – 29%
    Cladosporium 1 – 40 – 14%
    Pen/Asp 2 – 80 – 29%
    Stachybotrys 2 – 80 – 29%
    Background Debris 3
    Sample Volume (liters) 25
    TOTAL SPORES/M3 7 280

    Living Room
    Basidiospores 7 – 280 – 35%
    Cladosporium 7 – 280 – 35%
    Curvularia 1 – 40 – 5
    Pen/Asp 4 – 160 – 20%
    Stachybotrys 1 – 40 – 5%
    Background Debris 3
    Sample Volume (liters) 25
    TOTAL SPORES/M3 20 800

    Family Room
    Basidiospores 2 – 80 – 20%
    Cladosporium 4 – 160 – 40%
    Pen/Asp 3 – 120 – 30%
    Stachybotrys 1 – 40 – 10%
    Background Debris 3
    Sample Volume (liters) 25
    TOTAL SPORES/M3 10 400

    Basidiospores 3 – 120 – 43%
    Cladosporium 1 – 40 – 14%
    Pen/Asp 2 – 80 – 29%
    Stachybotrys 1 – 40 – 14%
    Background Debris 3
    Sample Volume (liters) 25
    TOTAL SPORES/M3 7 280

    Basidiospores 1 – 40 – <1%
    Cladosporium 1 – 40 – <1%
    Pen/Asp 297 – 11900 – 98%
    Stachybotrys 2 – 80 – <1%
    Tetraploa 1 – 40 – <1
    Background Debris 3
    Sample Volume (liters) 25
    TOTAL SPORES/M3 302 12100

    Outside Control
    Ascospores 6 – 240 – 9%
    Basidiospores 35 – 1400 – 50%
    Cladosporium 15 – 600 – 21%
    Curvularia 1 – 40 – 1%
    Nigrosporia 1 – 40 – 1
    Pen/Asp 6 – 240 – 9%
    Spegazzinia 6 – 240 – 9%
    Stachybotrys 1 – 40 – 10%
    Background Debris 3
    Sample Volume (liters) 25
    TOTAL SPORES/M3 70 2800

    1. The only things that stick out to me in these numbers are the Pen/Asp in the garage sample, however, air sampling in a garage is not standard industry practice since there is so much outdoor air exchange (unless this is a garage which has been built out as a living space). There is Stachybotrys present in all the samples, including outdoors, so this might be another reason for their suggestion. Since the indoor levels are so close to the outdoor level I would interpret those results as being acceptable.

      1. Thank you for your reply. By “acceptable” do you mean that you would feel comfortable living in a home with these numbers? Would remediation be suggested? I had a remediation expert out today and he said he saw no evidence of visible mold and wouldn’t even know where to begin remediation. There is nothing obvious to treat. He suggested maybe air scrubbers. What do you think?

        1. Running air scrubbers will filter out the particles in the air, and would hopefully remove any of the residual Stachybotrys spores. I can’t make any specific remediation suggestions since I have not assessed the property for visible mold and moisture. That remediation contractor seems trustworthy in that he did not try to sell you on any unnecessary treatments. Even without any Stachybotrys spores outside the indoor levels are still low.

      2. I just looked at my results again… I made a mistake by reporting Stachybotrys outside. There was NO Stachybotrys outside, but everything else is correct. Does that change your assessment?

  30. Hi Dylan: We had sampling done and it turned out that we have 1200 aspergillian/pen in our living room and 800 in our bedroom when AC is on. Outside reading was 80 We were away for 15 days when it was very hot in CA. Could this have caused it? Had all ducts cleaned as they were really dusty. Can we get rid of this by turning air on and airing out home or do we have to have a big remediation done? What is an acceptable level? Thank you so much. Your site is the best in trying to comprehend all of this!

    1. Sandra,

      There is not a concrete number for acceptable levels of mold in the air, we have to use the exterior levels as a baseline. The heat will not cause mold growth, there has to be some moisture for the mold to grow. This moisture could be humidity that might have been an issue when you were away. 1200 and 800 are not extremely elevated so I would not expect to need a large remediation, I would suggest doing a detailed cleaning of the home and possibly run a HEPA air purifier for some time to lower the levels in the air.

  31. Air Sample Analysis through EMLab P & K MoldSCORE in Naperville showed a moderate likelihood of indoor Penicillium/Aspergillus fungal growth, with a Mold Score of 155 (Below 150 they consider low likelihood). How can we clean this up? Is it possible to zero in on a concentration of it, or do we just have to clean the whole house again from ceiling to floor? Any suggestions are appreciated. Let me know if you need more info on our situation. Thanks!

    1. I am not familiar with their “moldscore” and how they assign those values. I can say that 350 spores/m3 of Cladosporium is not a high level. Outdoors we can routinely see levels over 1000. If you don’t have a history of moisture issues in the home and do not see visible discoloration I would suspect that these results are coming from the outdoor air, and it was just an anomaly that the outdoor levels were very low at the time of your testing.

      1. Sorry for the confusion… We had 350 spores/m3 (13 raw ct) of Penicillium/Aspergillus inside, and <7 spores/m3 (0 raw ct) outside. This came out to a MoldSCORE that was considered "moderate likelihood of indoor fungal growth". Cladosporium wasn't an issue in our house. It was found more outside than inside, as you said is usual. So, is 350 spores/m3 of Penicillium/Aspergillus in the normal range in your opinion? If not, any suggestions on what formula we can clean the house with? Thanks for the help!

        1. Yes, I would consider that to be a background amount unless you have had moisture issues in the home or see visible mold growth.

  32. Hello,
    We’re under contract on a house, built in 2006. There hasn’t been flooding but there were some drainage issues into the window well one very wet year that they fixed. I am very mold sensitive and recently went through a protocol to heal Chronic Inflammatory Response Syndrome from likely mold exposure in a house in Atlanta. Not wanting to go through it again, we had a mold test (air samples) done with the inspection, and here are the results. I’m not sure how to proceed, since there is the presence of Chaetomium in the basement. I don’t know if that should be a deal-breaker? Does it require remediation? Thanks for your help!
    spores/m3, raw ct, outside spores/m3, outside raw ct
    Penicillium/Aspergillus types: 270, 5, <13, 0
    Cladosporium: 320, 6, 590, 11
    Basidiospores: 160, 3, 320, 6
    "Marker" spore types (Chaetomium): 40, 3, <13, 0
    "Other spore types (Smuts, Periconia, Myxomycetes): 210, 4, 53, 1

    They lab provided a "MoldSCORE" for each of these, and listed the "Marker" type as MODERATE. The report said the following: "The MoldSCORE™ was in the MODERATE range for the following area(s): 2514 6000 (basement). A moderate MoldSCORE™ means that the results are inconclusive, and suggests that a more detailed inspection by a trained professional may make sense if there are any other reasons to believe that mold growth could be a problem in this room." Any advice would be appreciated! Thanks!

    1. The Chaetomium in the basement is a sign that there has been moisture issues in the basement. I would make sure that the basement is assessed very thoroughly to make sure that there are no ongoing moisture issues. I would proceed very carefully knowing there has been at least 1 moisture event in the past, and we are seeing Chaetomium in the air samples.

  33. I’m a teacher at an elementary school. Aside from my own illnesses that I’m concerned is coming from the building, 1400 kids are in this building as much as I am. The last IAQ test was done in 2014 & I’m having some trouble deciphering what it means. The test consisted of non-culturable spore trap air samples collected from a classroom and a hallway. These are a few of the results I have questions about from the classroom test.
    Pen./Asperg. Raw Cnt-14 Mult.-4 Spores/m3-373 57%
    Basidiospores Raw Cnt.-6 Mult.-4 Spores/m3 -160 24%
    Cladosporium Raw Cnt.-2 Mult.-4 Spores/m3 -53 8%
    Pithomyces Raw Cnt.-3 Mult.-1 Spores/m3 -20 3%
    Ascospores Raw Cnt.-1 Mult.-4 Spores/m3 -27 4%

    Are any of these numbers something to be concerned about?

    1. It is very difficult to give any meaningful analysis without knowing the outdoor levels at the time of the testing, but generally speaking these all look to be normal.

  34. Hi Dylan, thank you for your time. We renovated the basement into a separate living space this year. 2 months ago, an outside house was left on and it flooded the newly renovated area. A dehumidifier has been working since and the cork flooring was just pulled up 1 week prior to the air quality test. Here are the spore trap results from 10/30:
    Renovated area:
    Cladosporium: 10 raw count, 530 spores/m3
    Pen/Asp: 291, 16000
    Stach: 0
    In basement but right outside of renovated area, unfinished:
    Cladosporium: 10, 530
    Pen/Asp: 43, 2300
    Stach: 0
    Clad:6, 320
    Pen/Asp: 51, 920
    Stach: 0
    Clad: 7, 370
    Pen/Asp: 6, 320

    Your thoughts?

    1. The Pen/Asp levels are highly elevated in the basement. I would suggest cutting into some of the walls near the source of the leak for discoloration, i suspect there is some hidden mold growth in the space.

  35. Also some mold is visible along the baseboards of the renovated basement area where the cork flooring was removed. The moisture meter reported dry. Also there is some mold stains on the basement wall in the unfished area, probably from a leak from heavy rain 2 years ago. No visible mold or growth on other things.

    1. The visible mold growth should be cut out an removed. Any mold in the space should be removed. Running an air scrubber during and after the removal will clear the elevated levels in the air

  36. Hi Dylan: We have been on your site for weeks now, have had companies come in with quotes for remediation, but even you said levels were not high. We have just a few questions, but would like to call you or Ian. I thought I saw where there was a charge, but we don’t mind. Would that be possible? Thanks so much!

  37. Hi Dylan! I recently got back air test results and the following 3 types were show to be at elevated levels:

     213 count/cubic meter of air, compared to 40 Outside
    o Acceptable level is 200 count/cubic meter of air
     Curvularia
     760 count/cubic meter of air, compared to 40 Outside
    o Acceptable level is 200 count/cubic meter of air
     Pithomyces
     747 count/cubic meter of air, compared to 67 Outside
    o Acceptable level is 200 count/cubic meter of air

    Everything I’ve read online seems to indicate that Curvularia and Pithomyces are plant/grass/leaf related molds and we have no indoor plants? I’m confused as to how the levels could be so elevated in our hallway? Do you know what would likely cause these specific types to be so high? Or what you would recommend as a next step for these specific types?

    Thank you!

    1. Jennifer,

      These molds are all usually considered to be outdoor mold types. It is really unlikely to find these types growing indoors. If you don’t have any moisture issues or visible mold growth I would suspect these are coming from outdoors. I am not sure were the “acceptable level” numbers for these molds are coming from, background mold levels are very dynamic so it is almost impossible to assess “acceptable levels” like that, and I would not put much weight into that. Typically an outdoor sample is collected to be used as a control for the naturally occurring mold at the time of the testing.

  38. Hi there was wondering if its safe to stay in the home we are in right now. my step son has recently developed asthma since we started living in the home a year and half again. so i decided to get the air quality testing done since there is a leaking pipe in the home.

    Living Room
    Ascospores 10 (133m3) 4%
    Aspergillus/Penicillium 60( 800m3) 23%
    Basidiospores 163 (2173m3) 63%
    Cladosporium species 26 (347m3) 10%
    Total 259 (3453m3)

    Master Bathroom
    Ascospores 4 (53m3) 7%
    Aspergillus/Penicillium 10 (133m3) 17%
    Basidiospores 28 (373m3) 47%
    Cladosporium species 17 (227m3) 28%
    Nigrospora species 1 (13m3) 2%
    Total 60 (800m3)

    Ascospores 5 (67m3) 8%
    Basidiospores 17 (227m3) 28%
    Cladosporium species 38 (507m3) 63%
    Total 60 (800m3)

    1. Due to how much individual sensitivities affect how people react to mold, I can not say if it is “safe” or “healthy” inside a home. I am also not a medical professional so it is best to leave that determination to a qualified person. I can say that the levels inside the home do look mainly normal. there is a slight elevation of Asp/Pen in the living room, however, you can experience levels higher than that outdoors at some points in the year. If there was a large mold issue in the home affecting the air quality I would expect much higher levels in the home. With that being said it is very important to address any moisture issues in a home as quickly as possible to help mitigate the risk of mold growth happening.

  39. Hi Dylan,

    Great sight and appreciate you sharing the knowledge with common folks.

    How would you assess the following:

    Outside Air
    Type: Raw / per m3
    Ascospores: 20 / 1100
    Basidiospores: 84 / 4500
    Cladosporium: 20 / 1100
    Pen/Asp: 16 / 850

    Office Area
    Alternaria: 3 / 40
    Ascospores: 8 / 430
    Basidiospores: 21 / 1100
    Cladosporium: 13 / 690
    Pen/Asp: 10 / 530


    1. These results are a textbook example of a normal indoor environment. I don’t see any issues with mold in these results.

  40. Good Evening,

    I hope all is well, we recently had a mold test and we are extremely worried. We were told that we had elevated levels of Chaetomium in our Master Bedroom . I will do my best to present our results, would you be able to give me your opinion on the level of concern we should have and if Remediation is needed.

    Volume Sampled of each: 75L

    Master bedroom
    RawCt- Spores/M3 – %

    Basidiospores- 24- 312 -47%
    Ascospores- 3 -39 -6%
    Chaetomium- 1 -13- 2%
    Cladosporium- 9-117 -18%
    Penicillium/Aspergillus- 12- 156- 24%
    Smuts/Periconia/Myxomy- 1 -13- 2%
    Zygomycetes- 1- 13- 2%
    Background Debris -3
    Total Spores/M3 – 51 -663

    Control (Outside)

    Ascospores 21- 273- 6%
    Basidiospores 156- 2030 -42%
    Cladosporium 171- 2220- 46%
    Epicoccum 1 -13- <1%
    Penicillium/Aspergillus 18- 234- 5%
    Smuts/Periconia/Myxomy 6- 78- 2%
    Zygomycetes 1 -13- <1%
    Background Debris -3
    Total Spores/M3- 374- 4860

    1. A result with a single spore of Chaetomium is a difficult thing to interpret. It is possible that the spore is just an anomaly, we can see a spore in the outdoor air every once in a while, or it is also possible that the inspector may have been at a property with a mold issue before coming to your home and brought the spore in on his clothing or equipment. It is also possible that the spore is coming from internal growth.

      I would say if your property has a history of moisture issues, then I would have the air samples collected again. If the Chaetomium shows back up, or another water damage indicator mold is found I would say that is evidence that there may be some underlying mold issues. If your home has not had any issues with moisture, since the rest of the results look good, I would lean more on the side if the result not being statistically significant.

  41. Hi Dylan, I have read that Stachybotrys is not often found in air spore traps because the spores are heavy and earthbound. Given this should I be particularly concerned about the findings in my basement.

    Asp/Pen 41 – 1600 – 78.4%
    Basadio 5 – 200 – 9.8%
    Clado 3 – 100 – 4.9%
    Epicoccum 1 – 40 – 2%
    Stachybotrys 3 – 100 – 4.9%
    Totals – 53 – 2040 – 100%

    Asp/Pen 17 – 670 – 69.1%
    Basadio 5 – 200 – 20.6%
    Clado 3 – 100 – 10.3%
    Epicoccum ND
    Stachybotrys ND
    Totals – 25 – 970 – 100%

    Asp/Pen 9 – 400 – 10.1%
    Basadio 38 – 1500 – 37.7%
    Clado 50 – 2000 – 50.3%
    Epicoccum ND
    Stachybotrys ND
    Totals – 99 – 3980 – 100%

    1. You are correct, Stachybotrys spores are heavy and covered with a sticky coating. In nature, the spores have adapted to stick to insects and other things that might come across growth in the outdoors. We don’t often see Stachybotrys spores in outdoor samples for that exact reason. Your results do show that Stachybotrys is present in the basement, but it also shows an elevated level of Asp/Pen. I would suspect that there is some history of moisture in the space and likely hidden mold growth somewhere.

  42. Hi Dylan! I had a bathtub overflow and immediately (with 20 minutes) mopped up the water that had gotten on the floor by the tub. Unfortunately it seems that had seeped under the baseboard into the bedroom immediately on the other side of the wall. The bedroom carpet was wet for about 1-2 days. I put towels on the floor and immediately turned on an air purifier + a fan. I also put baking soda on the floor to speed the drying and ensure no odors. I had a mold test done and these were the results of the air samples. I live in the downtown Seattle area.

    Alternaria (raw, spores/m3)
    Bedroom: 0
    Bathroom: 1, 10
    Outside: 0

    Ascospores (raw, spores/m3)
    Bedroom: 226, 2260
    Bathroom: 294, 2940
    Outside: 405, 4050

    Basidiospores (raw, spores/m3)
    Bedroom: 4, 40
    Bathroom: 8, 80
    Outside: 53, 530

    Cladosporium (raw, spores/m3)
    Bedroom: 23, 230
    Bathroom: 12, 120
    Outside: 12, 120

    Myxomycetes (raw, spores/m3)
    Bedroom: 1, 10
    Bathroom: 0
    Outside: 1,10

    Penicillium/Aspergillus (raw, spores/m3)
    Bedroom: 26, 260
    Bathroom: 55, 550
    Outside: 13, 130

    Total Spores (raw, spores/m3)
    Bedroom: 285, 2900
    Bathroom: 371, 3700
    Outside: 485, 4900

    Thank you so much for your help!! I mainly want to know if I should be concerned–if yes, should I invest in professional remediation or could I instead handle this on my own (and if so, how)?

    1. Elizabeth,

      I don’t see anything particularly concerning with these results. The Asp/Pen levels are slightly higher than the outdoors, but typically in homes with Asp/Pen growth I see much higher levels than that (levels like 5,000 spores/m3). Unless you see visible mold growth, I would say there is no need for remediation based off these results.

  43. Here are the pre remediation numbers:

    Exposure: 15.00 l/min. for 5.00 min.
    Reporting Limit: 53 Spores/cu. m
    Sample Identification Raw Count Spores/cu. m Percent(%)
    Pen/Asp group 1 53 0.40%

    Pen/Asp 74 3,950 45.16%
    Basidiospores 37 1,970 22.52%

    Living Room
    Basidiospores 52 2,770 31.29%
    Pen/Asp group 8 427 4.82%

    Post remediation numbers:

    basidiospores 6 320 85.8%
    cladosporium 1 53 14.2%

    living room
    pen/asp 4 213 57%
    basidiospores 2 107 28.7%

    pen/asp 9 480 69.2%
    basidiospores 4 213 30.7%

    good enough?

  44. Hi Dylan,

    Happy Thanksgiving, and thanks for operating this site. I found some mold in my attic after a humid fall (Richmond, VA) and called to have an inspection. Since they were here, I asked for an air test. There was minimal surface growth in the attic, but they also tested two bedrooms and found concentrations of mold well above what I would expect, given that we’ve never had a moisture problem (7 years in the house) and have no visible signs of mold apart from the attic.
    The troubling counts:
    Basidiospores: 400/m3, 600/m3 (1000/m3 outside)
    Cladosporium: 200/m3, 1600/m3 (!) (1000/m3 outside)
    Penn/Asp: 1000/m3, 800/m3 (400/m3 out)

    The Cladosporium number scares the heck out of me–these are in our children’s bedrooms! More importantly, I’m just befuddled, as there’s no sign of mold in these rooms. We’re going to call a few mold remediation companies, but any guidance is appreciated. Thanks again.

    1. Kevin,

      I suspect that you might have some humidity issues inside the home. The slightly elevated levels of Cladosporium and Asp/Pen on these results are similar to what can be seen in homes with chronically high humidity. These levels are not a major red flag, we can commonly see levels higher than this in the outdoor air in the spring and summer. High humidity could also explain the mold growth in the attic in the absence of leaks.

      1. Thanks so much, Dylan. I don’t feel like it’s humid in the house right now (with the heat on), but it was definitely humid enough all summer and fall here in Richmond. Other than to check the humidity (and maybe a dehumidifier), is there anything we can do to get rid of what’s already there? Thanks again!

        1. Kevin,

          I would also try to figure out what is causing the mold in the attic. It is possible that some of the mold in the attic is affecting the air quality in the living spaces. Some common issues in attics are bathroom exhaust venting into the attic and lack of attic ventilation.

  45. Hello,
    These are my EMRI results for various rooms in the house. As far as I can tell they are considered “safe”. Although Aspergillus penicillioides has a 70 spore count. Also I read if you have even 1 spore of the toxic mold that could indicate a problem so I wanted to double check. Thanks
    Fungal ID \ Sample ID MAC-522/EC-Home: LR, Lndry, BRs, Kit
    Aspergillus flavus/oryzae 1
    Aspergillus fumigatus 2
    Aspergillus niger 25
    Aspergillus ochraceus 3
    Aspergillus penicillioides 70
    Aspergillus restrictus* 7
    Aspergillus sclerotiorum <1
    Aspergillus sydowii ND
    Aspergillus unguis 3
    Aspergillus versicolor ND
    Aureobasidium pullulans 51
    Chaetomium globosum 1
    Cladosporium sphaerospermum 18
    Eurotium (Asp.) amstelodami* 95
    Paecilomyces variotii 2
    Penicillium brevicompactum <1
    Penicillium corylophilum 14
    Penicillium crustosum* 1
    Penicillium purpurogenum <1
    Penicillium spinulosum* ND
    Penicillium variabile 6
    Scopulariopsis brevicaulis/fusca <1
    Scopulariopsis chartarum <1
    Stachybotrys chartarum 2
    Trichoderma viride* <1
    Wallemia sebi 13
    Sum of the Logs (Group I): 13.95
    Acremonium strictum <1
    Alternaria alternata 1
    Aspergillus ustus 33
    Cladosporium cladosporioides 1 390
    Cladosporium cladosporioides 2 15
    Cladosporium herbarum 4
    Epicoccum nigrum 71
    Mucor amphibiorum* 13
    Penicillium chrysogenum 6
    Rhizopus stolonifer 29
    Sum of the Logs (Group II): 11.09
    ERMI (Group I – Group II): 2.86

    1. Nicole,

      The responses in this blog post are all related to air samples using a spore trap cassette, which is not the same as an ERMI test. You can not use the same interpretation for air samples for ERMI testing. Because of how vastly different ERMI testing is compared to air sampling, and the lack of interpretation guidelines for ERMI testing, there is not a lot a consultant can determine with just looking at ERMI testing.

  46. Hi, I am prospective buyer of a house and we recently performed a home inspection and noticed some water damage in the basement. So they performed a mold test below are the results. The water leak was in the attic furnace and traveled down the walls to the basement. My question what does these results mean? And can this be fixed to the point where the mold would be completely removed and not come back. I am just concerned because I have 2 small children

    A)Penicillium/Aspergillus types** mold score of 300; 34,000 spores/m3; raw ct 629; outside <13 raw ct 0

    B) Cladosporium species spores mold score of 100; <13 spores; raw ct 0; outside 320 raw 6

    C) Basidiospores mold score of 100; <13 spores ; raw ct 0; outside <13 raw ct 0

    D) "Marker" spore types*** mold score of 100; <13 spores ;raw ct 0; outside <13 raw ct 0

    E) "Other" spore types***,****mold score of 100; <13 spores; raw ct 0; outside 106 raw ct 2

    1. Joe,

      I see a clear elevation of Asp/Pen in the sample. The most important part of remediation is making sure the moisture issues are corrected. In a situation like this, where the moisture is coming from floors above, it is possible there would be other areas of mold growth hidden in the walls since the route that the water flows from the attic to the basement could cause unsuspecting materials to get wet.

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