Mold clearance test & inspection timing details:

When to schedule an inspection and testing after a mold cleanup project. Here we explain and describe in more detail the post remediation mold clearance procedures and testing that should be used after a mold remediation or mold cleanup project.

When to Inspect & Test a Building After a Mold Cleanup / Remediation Project

This article is part of our MOLD CONTAMINATION ACTION GUIDE which provides an easy to understand step-by-step guide for dealing with toxic or allergenic indoor mold and other indoor contaminants: what to do about mold "mildew," moisture, in your house or office, building-related illness, involving your physician, treatment, sick building investigators, reduction of irritants, and special products to help clean buildings and air.

[Click to enlarge any image]

Article Contents

• MOLD CLEARANCE TIMING
  • WHEN to SCHDULE CLEARANCE TESTING
  • IMPORTANCE of STILL AIR CONDITIONS
  • CLEARANCE TEST PROCEDURES to AVOID
  • CLEARANCE TEST with RUNNING AIR SCRUBBERS?

Above: if the mold remediation contractor has called for a post-remediation clearance "test" we don't want to see moldy materials still on the job (photo at above left).

When to Schedule the Post-Mold-Remediation Clearance Inspection & Tests

As we noted at MOLD CLEARANCE INSPECTIONS and CLEARANCE PROCEDURES, the inspection and testing of a building to confirm that a mold cleanup project (mold remediation) has been adequately performed should not be scheduled until

1. After the mold remediation company has completed all demolition, moldy debris removal, and moldy surface cleanup that are to be performed
2. After the conditions that caused the mold problem have been corrected (lest we waste the cost of cleanup by having a new mold problem)
3. After any building air scrubbers or exhaust systems are off for 24 hours or more: equipment used during the remediation project should have been turned off for 24-hours or longer (to allow time for dust settlement indoors). See Sill Air Conditions, below.
4. Before the mold remediation project containment barriers have been removed. This permits the inspector to evaluate the workmanship of the containment system, its completeness, evidence of failure or collapse.
   
   More, this procedure also means that areas of the building outside the remediation work space remain protected against cross-contamination by moldy dust until the inspection and lab work have confirmed that the cleanup was successful. Finally, should the inspection or lab work indicate that more cleaning is needed, this process saves the cost of having to re-install containment as well as the possible cost of having to perform extra cleaning outside of the containment area.
5. Before the remediation area is re-occupied by people at extra risk from building air quality concerns such as asthmatics, elderly, immune, infants, etc.
6. While the building remains in still-air conditions: windows and doors to outside are closed.
7. Building mechanical systems:
   1. If weather conditions permit, the building heating or cooling system should be left off to avoid the risk of re-contaminating those systems before the successful clearance has been confirmed.
   2. An exception may be necessary in cold climates during freezing weather, or in hot humid climates to control humidity.
   3. HVAC systems serving the remediation area, their air handlers and duct work should be included in clearance inspection and testing, and if clearance includes (as we recommend) checking out of the cleanup area for cross contamination, all building HVAC systems should be included in that procedure.

CONTACT us to suggest changes or additions to this mold clearance inspection protocol.

The Role of Still Air Conditions in Post Remediation Mold Clearance Testing

Don't Perform Post Mold Remediation Testing Too Soon

24-hours of still air conditions is the minimum time we want to allow for settlement of airborne dust and debris in a buildings before conducting an air or surface dust screening test for mold contamination after a mold cleanup project. Longer dust settlement time is better.

Our photo (left) shows a very clean building basement that has been sealed as well. The air scrubber machine remained in the building but as we asked, it had been turned off prior to our onsite inspection. The containment barriers are not visible in this photo and would need to be verified if only part of the building was being cleaned.

At remediation jobs for which we have been the clearance inspector, we require no less than 24 hours of still air time. The containment is left in place, the air scrubbers are simply turned off.

That allows the clearance inspector to evaluate the quality of dust containment that was set up, and if, as sometimes happens, more cleaning is needed, the containment does not have to be put up a second time, thus saving some money.

And allowing settlement time means that if there was poor cleaning, and the air is still contaminated, we can often find that evidence in settled dust - more reliably than may be found by dashing in and simply grabbing a quick "air sample" (We use both methods).

We have rarely encountered a mold remediation company who objected to our clearance protocol - after all, the more confident everyone can be in the quality of the clearance inspection the more all parties are protected, including the mold remediator. In a few cases in which the remediator wanted us to test while their machines were running (and we have done so) once we explain the issues to the client, that has been the end of any debate on time periods.

Don't Perform Post Mold Remediation Testing Too Late

However, to protect the mold remediation company from being blamed for contamination that may have occurred due to subsequent building leaks or events, or from cross-contamination of the mold remediation work area by mold from other building areas that was excluded from the project (not an exclusion that we recommend), we suggest that

1. The post remediation clearance inspection and test be performed before mold containment barriers have been removed.
2. The post remediation clearance inspection and test should be performed in not more than five days after the completion of the cleanup project. 24-48 hours is recommended.
3. The post remediation inspection should include a report of visible or known conditions at the building that present a risk of future leaks, moisture problems, and mold contamination

Post-Mold-Remedation Procedures that are Specifically NOT Recommended Include

Violating any of the conditions described above

at MOLD CLEARANCE TIMING above.

Taking Down the Containment Barriers Too Soon

At left the mold containment at a doorway has been left in place in an area that has been reported to have been cleaned.

But sometimes the moldy dust containment system has fallen, been punctured, or even removed by the workers when it should have been left in place pending a successful mold cleanup clearance inspection and test.

Our photo (below left) was part of compelling evidence that the mold remediation crew at this New York City apartment cleanup job had been inexperienced to say the least.

The plastic containment barrier had been removed when we arrived to inspect the building. But we found a number of troubling conditions including

The plastic containment barrier had been "hung" from the fire sprinkler heads using duct tape strips.

Good grief. What if during the project someone pulls that down and sets off the sprinkler system, creating a new building flood?

What if there is a fire during the project and the sprinkler heads have been tampered-with or blocked?

And why was the ceiling cavity left open to receive dust during demolition, transporting it over other areas of the apartment?

Our second photo (above right) shows that the plastic used to seal around an air scrubber exit port had collapsed - probably not a serious failure at this job.

We understand that it can be costly for a mold remediation company to leave equipment idle at a property while waiting for the post-cleanup inspection, testing, lab work, report, and client approval. But that concern should not extend to early removal of the containment system as well.

The temptation to rip down the building containment system before the inspection and clearance test comes from several thoughts in the remediator's viewpoint:

• It seems efficient to take down and dispose of containment while the full remediation work crew is still on site - avoiding having to send laborers back to the jobsite after the clearance test
• The remediation company may be confident (perhaps sometimes overconfident) that their work has been successful
• The remediation company may not want the clearance inspector to evaluate their containment methods, especially where amateur workmanship have been involved.

By premature takedown of the dust containment system risks costs we introduced above.

• It prevents the inspector from supporting the remediation company's workmanship on the containment system by direct observation
• Early containment removal this procedure also means that areas of the building outside the remediation work space remain protected against cross-contamination by moldy dust until the inspection and lab work have confirmed that the cleanup was successful.
• Finally, should the inspection or lab work indicate that more cleaning is needed, this process saves the cost of having to re-install containment as well as the possible cost of having to perform extra cleaning outside of the containment area.

Leaving the Air Scrubbers Running

Remediators - some - would like you to test while their air machine is running, having the fantasy that even if they didn't remove all the mold they should-have, the scrubber will hide that fact ... until later, after everyone has gone and the remaining mold propagates again.

Sometimes this approach - leaving a scrubber on - allows the remediator to shoot themselves in the foot, especially when the company foolishly did not vent the air machine to the outdoors.

In that case if there is problem dust and debris remaining, the machine is simply stirring it up further. You cannot remove an indoor air particle problem by vacuuming the air. As long as the particle source remains there is, in a practical effect, an infinite particle source.

At left the air scrubber has been un-plugged, which in this case might help the mold remediation contractor from shooting herself in the foot with the loose dirt and debris that had yet to be removed. The call for a post-remediation mold inspection and test might be premature if you see debris left in the jobsite: if there was enough mold contamination to merit professional cleaning, then that debris is likely to be mold-contaminated.

See our discussion

on CONTINUED USE of AIR SCRUBBERS.

Leaving Building Windows & Doors Open

A second approach that some remediators like is to have the clearance performed while the building is being aggressively ventilated with outdoor air. This too can obscure an in-building remaining mold or particle source problem in or out of the remediation area, and in some conditions can also bring in excessive levels of outdoor pollen or mold. Or moisture, or even rain at an unattended building.

While ventilating a building with outdoor air may work in some cases to help clean up a building interior, it is impossible to distinguish reliably between outdoor conditions and indoor building conditions if the building windows and doors are open 24-hours before or during the clearance inspection.

U.S. EPA Guidance for Mold Clearance Inspection After a Mold Cleanup

Our complete collection of US and international mold standards references are collected at

MOLD EXPOSURE STANDARDS.

From the US EPA we include this more general advice on the criteria for a mold cleanup job: [Our comments are in italics]

How Do I Know When the Remediation or Cleanup is Finished?

• You must have completely fixed the water or moisture problem before the cleanup or remediation can be considered finished.
  
  [See MOLD PREVENTION GUIDE]
• You should have completed mold removal.  Visible mold and moldy odors should not be present.  Please note that mold may cause staining and cosmetic damage.
  
  See MOLD CLEANUP, VISUAL CHARACTERISTICS and see ACCEPTABLE MOLD LEVEL.
  
  Remember that no building is mold-free except perhaps inside of a manufacturing "clean room" - mold exists in air everywhere and small amounts of molds will be found in settled dust just about everywhere - don't set a target of "zero mold".
  
  If the "mold remediation" job has left extensive dirt and debris in the remediation area (photo above left) it is unlikely that the work was successful nor that it was performed by properly-trained professionals.
• You should have revisited the site(s) shortly after cleanup and it should show no signs of water damage or mold growth. 
  
  See MOLD CLEARANCE TIMING.
• People should have been able to occupy or re-occupy the area without health complaints or physical symptoms. 
  
  See MOLD RELATED ILLNESS GUIDE
• Ultimately, this is a judgment call [and must include an understanding of the original location, extent, type, and cause of mold contamination that was to be removed as well as the chances of other mold contamination in the building that was not addressed];
  
  there is no easy answer.
  
  If you have concerns or questions consult our Frequently Asked Questions database and ask a question [or Contact Us directly at InspectAPedia.com] if you don't find what you need.

Continued Use of Negative Air Machines & Air Scrubbers During the Remediation Clearance Inspection & Test?

The following discussion between D.H. and Daniel Friedman, InspectApedia.com editor. We welcome polite argument, comments and suggestions through the page-bottom COMMENTS BOX or by direct email CONTACT Us .

At left, an air scrubber in use at a mold-remediation job that looks (from here) pretty clean. But we do need to look up inside the wall cavity at the back of the remaining drywall.

Betty Crocker Recipe for Remediation is Questionable

I have a question concerning turning off the air scrubbers 24 hours prior to sampling. Each project is unique and I think remediation protocol needs to be flexible enough to cover the different situations encountered, as long as the efficacy and quality of the job is not compromised.

So, my concern with a general, “Betty Crocker recipe” is this: if you are using the equipment as a negative air machine while remediating, then switching to air scrubbing mode before sampling, you will lose negative pressure differential and increase the chances of cross contamination.

If you use separate equipment for negative air and scrubbing, you are sampling make-up air. I believe there are too many variables on each project to have a general rule covering all situations. You may need to include surface samples of the settled dust when air scrubbers are off.

You could condition make-up air if you maintain negative pressure differentials. Again, the problem is more complex than it initially appears. - D.H. 29 July 2015 by private email

Reply - DJF: Turn off the air scrubbers.

I agree that post remediation inspection and testing deserve careful thought and that a too-rigid procedure is probably going to make trouble.

My opinions on this matter derive from both field and lab experience.

"Air Scrubbing" in a typical residential building is something the remediator does hoping to improve the chance of a "pass" on a post remediation air test for mold.

Air testing for mold is fundamentally unreliable as I have amply tested and proven at least to my own satisfaction. A small change in the environment can produce 1-4 orders of magnitude differences in the level of airborne particles.

See ACCURACY OF AIR TESTS for MOLD.

Culture tests, for those inspectors who like swabs or culture plates to "characterize" the mold genera/species present in a building or to count colony forming units, are essentially 90% "wrong" when you open the kit lid.

See MOLD CULTURE TEST KIT VALIDITY.

Furthermore, "scrubbing" air in an environment where the cleanup was incomplete or otherwise inadequate is as futile as trying to vacuum dust bunnies from under the living room couch by standing in the kitchen waving a vacuum cleaner wand in the air.

I and some others want all equipment that is unnecessarily stirring up air turned off 24 hours before a post-remediation inspection in order to

• Represent the conditions that occupants will endure. So I don't want a "false low" because the remediation area is sealed up, air scrubbers are running like mad, but the cleanup was inadequate. I've seen this condition many times, with visible piles of leftover moldy dirt and debris on floors while the scrubber is scrubbing away. The persistent source had not even been removed.
• Permit settled dust sampling

At above left the Aspergillus sp. spores in long chains tell us that this mold came from somewhere in the building - it didn't blow in the window from outdoors. We do not expect to find "zero" mold spores in a cleaned building, though often after an expert and successful mold remediation job the building will be cleaner than a comparable building that has not suffered water leaks, mold damage, and thus mold remediation.

A "zero" mold level report would suggest that the sample was suspect.

At above right we see a high level of Aspergillus sp. spores and spore chains in a settled surface dust sample from a mold-remediated surface.

It's important to test a surface that had been wiped quite clean so that we know that the dust we are examining is settling after the mold cleanup job has been completed. With this sort of moldy dust around I'm doubtful that scrubbing the air in the building is going to be very helpful.

We should always be looking at settled dust for dominant particles but at the same time we should not be looking for "zero mold" in the dust samples of a remediated building.

Finally, "testing" without an informed inspection is fundamentally unreliable as well.

"Betty Crocker" I'm not, more like Davey Crockett, intolerant of airborne baloney rather than serving it up in sandwiches.

If you agree I'd like to post your comments and our ongoing discussion at the start of my article series on this

at MOLD CLEARANCE TIMING

Also see MOLD CLEARANCE INSPECTIONS - home.

and I much welcome further critique or suggestions. - Daniel

Reply - DH:

I would love to hear from some of the people on the front line and their thoughts. These types of conversations are what expands our knowledge and keeps things interesting.

I can certainly see (and in many cases agree) with your approach. It is unfortunate that many times we have to assume that people are chasing money or taking unwarranted shortcuts in order to “pass” the PRV, instead of concentrating on doing a good job. A “good job” is a moving target, involving real-time adjustments during the process. I hope we get some comments on the pros and cons of each side of the issue.

A good start are the questions: “Are there times when the scrubbers should be turned off and other times when they should be left running?” What are the situations that would indicate which action is appropriate?”

I’m looking forward to see what others have to say!

Reply - DJF

At above left the remediator had told me the job was ready for a clearance test. Similarly at above right the crawl space had been "remediated" for mold contamination using the "spray and pray" method. Wet moldy debris remained along with contaminated insulation.

[Click to enlarge any image]

I can't think of any time that scrubbers should be left on for post remediation clearance; rather the remediator should have completed the cleanup. Think of it this way: if on turning off the scrubber the level of airborne contaminants soars then there is a problem that s/he was covering up by continuous scrubbing.

And if turning off the scrubber wouldn't change the results, then what are we worrying about.

I might agree however that negative air handlers need to be kept running as part of a building containment system (in a structure where only part of the building is being treated) until a successful clearance inspection and test are completed. I understand that there are costs involved and sometimes people are hot to use the negative air machines elsewhere or for a smaller remediator, to stop renting them.

But IMO another remediation sin (and one I found committed about half the time on small jobs back when I still did real field work) is to remove or subvert the containment system before the remediation job is passed. You've probably seen some of these disappointing cases: wet building, mold growth, partial mold removal, leak not fixed, new mold growing on "remediated surfaces" visible at the time of the clearance inspection. Ick.

Everyone, including the mold remediation company, is best served by a thoughtful and diligent post-remediation inspection and test procedure that leaves all parties confident that the job has been properly performed. If the post-remediation clearance inspection and test give a green light to the mold cleanup-job that should mean that if in the future actionable mold contamination is found in the building then it must be from a new event and not a left-over un-clean area from the previous job. - DJF

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2017-05-25 by (mod) - avoid mold inspector conflicts of interest

Best is an inspector who has no business nor financial nor other relationship with the company who performed the actual mold remediation work.

On 2017-05-25 4 by Charles shark

Who is the post mold clearance inspectors

On 2017-05-06 - by (mod) -

Note again my comment about the size of the mold contamination.

UK form an opinion about the quality of cleanup by testing a sample of Representative settled dust. Use the on-page search box at the top or bottom of this page to search a website for mold test kit to see an easy and inexpensive way to do that. Don't send mold samples to us send them to any mold testing lab.

In my experience exposure to high levels of harmful molds, or protracted exposure even to lower levels, will in some people and do some old sensitivity and can explain various illnesses including respiratory distress. These are questions to discuss with your doctor comma as you've indicated you will most likely be doing

On 2017-05-06 by Elena

Dear Dan. I deeply thank you for your prompt reply. The mold area of interest, at this point, has been only my bedroom, but this apartment suffered major leaks since I moved in (over a decade ago) and nothing has done in the past if painting over the water damaged area.

The dehumidifier has been running (3rd day now) INSIDE the contaminated/remediation area and it was on when Landlord's air test company took the test for clearance. I am not sure if this is the right procedure.

I only know I have been feeling the same reactions I had during last leak: shortness of breath, nasal and facial burning feeling, lungs tightness. By all mean, I am not searching for medical help by submitting this inquiry. I am just concerned that the remediation method used is not the proper one. I thank you again. Sincerely, Elena

On 2017-05-06 - by (mod) -

Elena:

If the largest total area of contiguous moldy materials was less than 30 sqft. expert sources agree that normal building cleaning crews and cleaning methods should suffice. If larger areas were involved then professional remediation, dust containment, etc. are justified.

If the remediation did not include finding and correcting the cause of mold growth in the first place then the job will not be successful and mold contamination will recur.

Air tests alone, without an expert inspection for the scope of original contamination, scope of cleaning work, completeness of cleaning and of removal of non-cleanable materials (like insulation and drywall), will not be reliable, particularly when results are "negative" since what's in the air can vary by orders of magnitude depending on just how and when a test is conducted.

There is argument about leaving machines running before and during post remediation inspection and testing - often the remediator thinks that leaving a negative air machine running or an air filter running will lower airborne counts and increase the chance of "passing" such a "test". A more reliable approach is to turn off all air moving equipment for 24 hours, then besides inspection, sample settled dust; I don't mind air sampling done at that same time but air alone: unreliable.

If the dehumidifier was not running near the remediation area then it probably wasn't disturbing air, but it suggests to me a worry that no one has found and fixed the leaks or trapped moisture that caused the mold problem.

On 2017-05-06 by Elena

Object: post remediation clearance test. First of, great website. Very informative.

However, I am going through so much confusion I thought asking an expert in order to have some understanding. I had a bad mold situation in my bedroom. Air sample test revealed Aspergillum, Penicilium in elevated quantity. C

avity sample revealed also Stachybotrys. Landlord has been really sketchy about the whole thing. The so called "remediation" was done by the repair crew that he uses for regular repairs. The containment was poorly done and they never used an air scrubber after removing part of the wall and ceiling.

After removing debris, instead they placed an industrial dehumidifier (contair ct125) with a tube that goes in to my bathtub, an area outside containment. After 2 days (with dehumidifier on) today they came to perform the post remediation clearance test and the dehumidifier was on while performing air test. Is this a regular way to perform a post remediation clearance test? Sincerely, Elena

On 2017-03-16 - by (mod) -

Of course one would not operate negative air machines (NAMS) during sampling - not only does that stir the air far more than usual, the remediator is hoping that that will hide a remaining cleanup problem by reducing the level of indoor airborne particles.

Dust sampling of a surface will always give a better indication of what's on surfaces than air sampling.

Any measurement of the leel of small airborne particles varies by 4 orders of magnitude depending on how a sample is collected, so numbers from air sampling are totally method and environment dependent and are very inconsistent.

At most, I might use a mix of sampling methods, but I'd not rely on air sampling alone. The problem is the risk of finding a false negative.

You're spot on in suggesting another more fundamental problem: field investigators do not use consistent methods when examining air or the environment in buildings.

Thanks for the comment.

On 2017-03-16 by Jim Pearson

re: Mold Clearance Timing. Your article implies that shutting down AFDs for 24+ hours prior to sampling allows the dust to settle and yields a more accurate sampling result which is similar to what the occupants experience when moving in (eg;, no operating AFD during sampling).

It is my opinion that one should NOT operate NAMs or AFDs during sampling, BUT I feel disturbed air sampling will better reflect what is really in the air and on surfaces. Additionally, there is a White Paper at IAQA regarding this NAM ON / NAM OFF debate.

I presented it at an IAQA Conference a couple of years ago. There is much to consider here and it's an area that is not yet settled. Jim

Question:

(Dec 27, 2012) Paula Otani said:
We are considering purchasing a home which was used as a grow op for 6 weeks only a year and a half ago. All remediation work has been completed and two separate air tests have shown no significant amounts of mold spores in the air.

Insurance companies are reluctant to ensure the property in case there are mould issues down the road. How long is a suitable time to reasonably assume that any mould issues from the grow op have disappeared?

Reply:

If the cleaning and inspection and testing were done properly then the result should be documentation that would should convince the insurer that if there is a mold problem in the building in the future it will be due to a new event.

And vice versa. I'd start by reviewing the documentation and by making sure that the inspection and clearance professionals had absolutely no relationship with the cleaning company nor seller nor realtor.

...

Continue reading at ACCEPTABLE MOLD LEVEL or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• MOLD CLEARANCE INSPECTIONS
  • CLEARANCE PROCEDURES
  • MOLD CLEARANCE TIMING
  • ACCEPTABLE MOLD LEVEL
  • MOLD CLEANUP, VISUAL CHARACTERISTICS
  • MOLD LEVELS IN BUILDINGS
  • MOLD CLEARANCE: FOLLOWUP STEPS
  • MOLD CLEARANCE TEST, SUCCESSFUL
• MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
• MOLD PREVENTION GUIDE
• WHEN TO STOP LOOKING FOR MOLD

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