Mold contaminated apartment ceiling (C) D Friedman and SMIndoor Air Quality Problem Definition
How to decide if a building has an indoor mold or similar IAQ problem?

  • DEFINITION of IAQ PROBLEM - CONTENTS: how do we know if there is (probably) an indoor mold contamination problem or simlar IAQ issue? How do we know when to hire an expert?
  • POST a QUESTION or READ FAQs about how to decide if a mold, odor or other indoor air emergency exists, what to do in an emergency, and how to determine if professional mold inspection & testing are needed
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Definition of indoor air quality problem status:

This article describes how a building owner or occupant may conclude that there is evidence of an indoor air quality problem - enough to decide to take further action.

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Definition of Indoor Air Quality Problem - how to know if you have an IAQ problem in your building

Photograph of an almost-correctly protected mold investigator at work in a moldy basement.An expert who is asked to determine whether or not a building has an actionable mold contamination problem (or other indoor air quality problem) will interview building occupants, owners, maintenance staff, conduct a thorough inspection of the building inside and exterior to identify both visible mold and conditions that make a hidden mold problem likely, and s/he may conduct tests of indoor surfaces, settled dust, or air to help identify problem areas.

Not every mold worry merits a costly onsite investigation. But failing to hire an expert when one is needed can itself be a costly mistake.

There are both obvious evidence as well as more subtle clues that assist a building owner, occupant, home inspector, or buyer in deciding if a building has or is likely to have an indoor mold contamination issue, including the following:

  • A large area of visible mold anywhere in the building (see photo at page top). "Large" for this purpose means more than 30 sq.ft. of contiguous mold. Some steps might be needed to rule out cosmetic mold however.
  • Indoor air complaints following a significant building event, leak or flooding, even if extensive mold is not visible. Other indoor air quality hazards such as chemical contamination might be sensed following application (or improper application) of pesticides, application of paints, installation of new carpeting, cabinets, tile, other furnishings, or changes to the operation of the building HVAC system.
  • Individual indoor air complaints may indicate an indoor air quality or mold problem, though there could be causes not related to the building too. Keep in mind that individual sensitivity to mold, allergens, and other indoor contaminants varies widely so one person may suffer while others may not sense any problem.
  • Widespread occupant complaints about building conditions: if complaint symptoms (such as symptoms similar to colds, allergies, fatigue, flue, allergic reactions, or reactions of asthmatics) are widespread among building occupants, those form a stronger problem indicator.
  • Occupant complaints that occur only while inside the building and that diminish or stop when the occupant leaves the building. Also, because exposure to molds, MVOCs, and other respiratory irritants can increase individual sensitivity or can produce long-lasting symptoms, we do not rule out the building as a cause or contributor when individual complaints persist after leaving the building.
  • A physician has found that a building occupant has a building-related illness. That is, the doctor indicates may be caused by or aggravated by exposure to a contaminant in building indoor air.

Watch out: the EPA and other experts warn that the absence of apparently-building-related symptoms does not guarantee that the building indoor air quality is acceptable. For example, some diseases (such as asbestosis or lung cancer) might be due to long term exposure to airborne asbestos, radon, or other chemicals, carcinogens or pathogens. [5]

If you are not sure if a mold emergency exists

If you feel unsafe, follow the advice given above.

Additional information is at

Reader Question: Moldy Rental Apartment Ceiling - Is this Serious? Do I need a Mold Expert?

Mold contaminated apartment ceiling (C) D Friedman and SMI was hoping to get some quick advice from you regarding my mold problem, and the sooner the better.

I feel as though my management and landlord are pressuring me to just do a paint job and don't want to admit there is mold because of their liability and costs, and I don't know that I can trust expert advice if I call in mold specialists (as you articulate in your amazing guide to mold). I also do not have the money to call in experts and seek advice, as I am currently a student and in a great deal of debt.

I understand that you cannot give me exact advice based on a photograph, but I am at least hoping that you can just give me an opinion as to whether I should call in an expert for the problem.

I live on the 10th floor of a fairly nice apartment complex, and this mold has appeared in my bedroom. The room is not ventilated with open windows, but it has the sole convector that is both the AC and heat in my building. It appears like it originated from upstairs, or for the convector (which is just under the visible window in the picture). The mold grew rather quickly and spread fast, and I believe it may be irritating my mild asthma. I live in Washington DC, which is a very humid place.

My concern is this: I do not want to have to rip out walls as I am in the middle of a school semester and that would not be ideal since I would have to relocate; meanwhile, I don't want to bleach and paint over it, only to have this problem arise again. I understand that you may not be able to give me expert advice through a simple photo, but in case you can tell me whether this problem looks serious or not, I thought to email. Because of my asthma, I understand that you may be obliged to recommend an expert, but if that was not a concern and a paint job will suffice, that would be ideal for my school work.

I know this may be unreasonable, but I am hoping you can get back to me tomorrow as my landlord is coming to see the unit and I want to be able to make a good argument and uphold my right to have a livable apartment. However, your advice would be much appreciated whenever you can give it, whether tomorrow or weeks or months from now.

Thank you so very much, and more specifically, thank you for your guide - it was the most helpful thing on the internet! - S.M., D.C.

Reply: A Paint-over of an extensively mold-contaminated ceiling is out of the question. Professional mold inspection and a remediation plan are most likely needed in this case

My opinions below are based on your email, your photograph, and my own field and lab experience in building mold contamination diagnosis and remediation. Naturally a competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem and that would permit recommending the proper steps to correct these conditions. That said, here are some things to consider:

Basis for Opinion that Professional Mold Inspection & Cleanup are Needed

Extent of Visible Mold:

Your photo shows heavy black material on a ceiling that from your description sounds and looks as if it is almost certainly mold. It would be unusual for only one mold genera/species to be present under these conditions, so it would be an error to assume that the black mold you see is the only mold there nor even that it is the largest mold reservoir nor that the black mold is the most harmful mold present.

For example, if the mold growth was caused by leaks into the ceiling cavity from above, there could be a larger reservoir of mold in that space.

The mold growth pattern suggests that it is following a previous paint pattern, though there could be other explanations. More significantly, there is almost certainly more than 30 sq.ft. of contiguous moldy surface in this area. In your photo it looks as if mold growth is extending down the building walls from the ceiling area.

Health Risks of Occupants

Your concern for irritation of asthma is a very reasonable one. In my experience both chronic exposure and short term high level exposure to at least some molds can increase mold sensitivity and even induce severe allergic or asthmatic reactions in some people. The longer you are exposed the greater the risk.

Conclusions: hire a mold expert

Under these conditions, and as we discuss at MOLD / ENVIRONMENTAL EXPERT, HIRE ? it is very apparent that professional inspection and diagnosis of the location and extent of mold growth and the steps necessary to not only remove it but stop future mold growth in the area are what's needed.

My conclusion is that the problem looks serious and that you need a competent onsite professional to confirm the extent of mold growth, its cause, and the steps needed to correct the condition. As you are renting this apartment you will want to determine who is responsible for fixing this apartment mold problem, and even if you bear none of the responsibility you'll want to assure that it is handled correctly.


Warnings about Mold "Tests" and "Treatments"

I don't mean just "mold testing" - which would not be helpful.

In addition, because of the amount of moldy surface, it's likely that dust containment, negative air, and steps to protect your own belongings as well as the apartment contents will be needed during demolition and cleaning of the surfaces.

Simply painting, spraying, or surface treating these areas would be an inappropriate approach. YOu'd be leaving mold-contaminated ceiling materials in place, perhaps a significant problem in the ceiling cavity, and almost certainly the cause would by that approach remain un repaired. When there is moldy drywall the proper repair is to remove that material - it cannot be reliably cleaned and the hidden side would remain un inspected and untouched as would any mold in the cavity above.

Does it Make Sense to Try an Emergency Seal-Off of the Moldy Area?

While I do not recommend it in this case, in an emergency in which an occupant simply cannot move out of an area to permit necessary mold cleanup work, it might make sense to install a continuous 6-mil poly plastic temporary mold barrier covering over all of the contaminated surfaces as a short term stop-gap measure.

The problem with this approach is that no one has adequately determined the extent of mold contamination: the barrier may be incomplete or inadequate. Also the barrier, by trapping moisture, is likely to increase the mold growth problem, and finally, because the cause of growth has not been determined I'd have little confidence that it would not appear soon outside the barrier.

Need to Move Out of a Moldy Apartment? Protect or Clean Items to be Moved

I am sorry to say that in the case that you describe the problem room needs to be isolated from the rest of the apartment. If this cannot be achieved then indeed you may need to move elsewhere during the remediation. That question will be answered by a professional inspection and by the mold premeditation company. Watch out: if your apartment contents become contaminated with mold growth, or more likely in this case, moldy dust, they may need cleaning before you move them to the new residence.


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DEFINITION of IAQ PROBLEMat - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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