Re: Air Clearance Sampling for Mould

[Guest guest]

I am going to take an early crack at this. I know it will stimulate

discussion.

My preference is to have negative air pressurization operating until

clearance has been given. This means there is very active exchange with

outdoor air, and comparisons of indoor air to outdoor air are

straightforward (but conclusions with real data may not be). There are

certainly weather conditions when this arrangement is not appropriate,

and there are many projects that have air scrubbing only, negative air

plus air scrubbing, equipment on or off for some length of time, or none

of the above. In each case, comparisons may not be straightforward, and

the consultant generally has to use their judgment in evaluating the

results. I specify sampling from outside the building, inside the

building but outside of contained areas, and inside contained areas to

provide additional sets of potential comparisons.

My specification for post remediation verification, include the

following passages. You will note the influence from State of Texas

regulations. I will appreciate all thoughtful comments and criticisms.

Don Schaezler, Ph.D., P.E., CIH

ETC Information Services, LLC

Cibolo, Texas

Post-Remediation Activities

Post-remediation activities will include the following activities, which

will be performed by or under the on-site direction of a Licensed Mold

Assessment Consultant (MAC):

1. Containment and negative pressurization shall remain in place

until clearance has been established by the MAC.

2. The remediation areas shall be inspected for correct set-up,

operation of equipment, general cleanliness, dryness of materials, and

completion of the scope of work outlined in this Remediation Protocol,

as defined in Attachment B. If any location is determined to be

deficient, the post-remediation activities will be suspended until they

are corrected.

3. Photographs shall be taken of each remediation location in each room.

4. Sampling and analysis shall be conducted as defined in Attachment B.

5. Report on inspection and clearance activities, including

documentation of all field activities, measurements, photographs, and

sample results

Attachment B

POST REMEDIATION VERIFICATION PROCEDURES

Introduction

Remediation verification or clearance of remediation projects typically

includes the following elements:

1. Observation of the building systems to ensure that sources of

moisture intrusion or leakage have been corrected.

2. Observation of remediation methods to ensure that proper

remediation procedures have been used, and that the scope of work

completed satisfies the requirements of the Remediation Protocol.

3. Visual inspection of the work area after remediation has been

tentatively completed to ensure that there is no visible mold growth or

fungal rot, no excess dust or debris in the work area, and that surfaces

do not have excess moisture content.

4. Field measurements of temperature, relative humidity, and moisture

content of materials to ensure that conditions are consistent with

clearance of remediation of mold contamination.

5. Surface sampling to ensure that cleaning has been adequate and

that no more than background levels of fungal spores are present after

remediation.

6. Air sampling to ensure that there are no hidden reservoirs of

fungi or fungal spores and that the air has been cleaned sufficiently so

that indoor air is qualitatively similar to outdoor air.

Field Measurements - Criteria

1. Each remediation location in each room shall be measured for

moisture content using field moisture meters. Materials shall have

moisture contents less than the following:

Sheetrock: 0.5%

Wood: 15%

Concrete: 3.5%

Ceramic Tile: 3.5%

2. Each remediation area shall be sampled for temperature and

relative humidity. Relative humidity shall be less than 60%.

Clearance Protocol - Surface Samples

1. Select representative locations within the remediation areas and

collect composite surface swabs from each representative location.

2. Swabs should be handled to avoid contamination and should be used

to collect materials from at least 100 cm2 per swab. When sampling has

been completed, return swab to tube, seal with tape, mark for

identification, and package for shipment to the Licensed Mold Analysis

Laboratory.

3. There should be at least one swab for each remediation area or one

swab per 200 square feet of floor space within each remediation area.

There should be at least two swabs from similar materials in background

areas outside of remediation.

4. Submit the samples for enumeration of fungal spores and mycelial

fragments and identification of fungal spores by microscopy. The

analysis required is designated as S001 by Aerotech Laboratories, Inc.,

Phoenix, Arizona, a leading laboratory for this type of work. The

equivalent analysis by any AIHA-accredited (environmental microbiology)

laboratory, licensed by the State as a Licensed Mold Analysis

Laboratory, will be satisfactory.

5. The samples will be deemed satisfactory if any one of the

following occurs:

1. Total fungal spores are less than 10 times the detection limit for

the analysis (approximately 1 count/cm2), or

2. Total fungal spores are less than 10 times the average for the

samples from the background areas.

In addition, there must be no more than trace levels of

Aspergillus/Penicillium-like spores, Stachybotrys spores, or Chaetomium

spores.

Clearance Protocol - Air Samples

1. Collect Air-O-Cell samples from each remediation area.

2. Air-O-Cells should be handled to avoid contamination and should be

used to collect at least 75 liters of air per sample. When sampling has

been completed, seal openings, mark for identification, and package for

shipment to the Licensed Laboratory.

3. There should be at least two samples for each remediation area or

one sample for each 500 ft2 of floor space within each remediation area,

whichever is greater.

4. There should be at least two samples from outside the building for

reference.

5. There should be at least two samples from background areas inside

the building but outside of remediation, if applicable.

6. Submit the samples for enumeration of fungal spores and mycelial

fragments and identification of fungal spores by microscopy. The

analysis required is designated as A001 by Aerotech Laboratories, Inc.,

Phoenix, Arizona, a leading laboratory for this type of work. The

equivalent analysis by any AIHA-accredited (environmental microbiology)

laboratory, licensed by the State as a Licensed Mold Analysis

Laboratory, will be satisfactory.

7. The samples will be deemed satisfactory if the following occurs:

1. Within the remediation area, the average of all samples is less

than the average outdoor air value.

2. The diversity of spore population for the average of samples

within the remediation area is similar to that for the average of

outdoor air samples.

In addition, there must be no more than trace levels of Stachybotrys

spores or Chaetomium spores, unless these spores are present in outdoor air.

asishk@... wrote:

> *Hi all:*

> **

> I have a question for the group.

>

> Should HEPA Air Scrubbers be turned On or Off During Air Clearance

> Sampling for mold? What are the pros and cons?

> I did a quick search on " Google " . The first hit I got is a book from

> Safety-EPA.com.

> Bob, is this your book? " Post-Remediation Verification (PRV) of Mold /

> Bacteria Remediation Projects - Risk-Based Levels of Cleanliness

> Standards " .

> Sincerely,

> Ash

[Guest guest]

Okay, first, I need to say I'm not a mold specialist, just an interested layperson..

But this is what I would do, if I were the person whose house was about to be tested..

I would want all air cleaners to be off for at least three *days*

before the sampling was done, and I would also want to have the windows

be closed, so as not to dilute the indoor air with outdoor air.

If you want the sampling to be accurate, I'd also do it when there is a bit of a wind outside, preferably in the afternoon.

(but again, with the windows shut)

I'd also want the weather conditions to be typical. Mold spore levels

tend to peak in warm periods following wet periods..however, this isn't

as relevant if the mold is coming from plumbing leaks, etc. Or from

condensation.

If a building has stood unoccupied, be aware that people transpire

quite a bit of moisture and so a building might be much dryer without

people in it, with regard to condensation on cold outer walls or inside

HVAC equipment..

Others will probably have other opinions..

Air testing is fraught with lots of problems.. some kinds of molds

rarely show up in air testing even when they are very serious issues..

(stachybotrys) other kinds of mold toxicity (mycotoxins) can come from

particles of dried out mold material that won't be identified as such

because they are not spores..and so cant be identified by microscope..

(this is often the situation in buildings that have had *longstanding*

uncorrected mold issues.. that have been 'addressed' by stopping

moisture incursion, but not removing the mycotoxin laden materials -

they can be very reactive for people - in other words, sick buildings,

but the spore counts are deceptively low.. what needs to be done is

testing for mycotoxins - )

[Guest guest]

Ash,

That is the book, the committee reviewers commented on this issue at

length. It was probably one of the most difficult and contentious

issues. The discussion can be found in

Chapter 6. POST-REMEDIATION VERIFICATION DOCUMENTATION PROTOCOLS

Section H. Analytical Clearance Testing

Subpart e. Should HEPA Air Scrubbers Be On or Off During Analytical

Clearance Air Testing?

Basically, it comes down what you are trying to test for. If you

leave the scrubbers on, then your acceptability criteria have to be

very very low because you are constantly filtering the air.

On the other hand, if the scrubbers have been off for 24 hours and the

space has equilibrated, then more normal cleanliness criteria can be

applied in evaluating the space.

Bob

[Guest guest]

Don,

I like your protocol a lot. I'm not familiar with all of the TDH requirements that it addresses. I have two comments for discussion:

1) when I test with the negative air machine running, I have concerns about laminar air flow creating certain "zones" of clean make-up air so that the sample location in the work area is critical. I don't like to shut the machine off and lose negative air in the containment, but I prefer to let the air "homogenize" by turning the machine off for a brief period (5-10 minutes) to get a more "reliably representative" sample.

2) The method of direct microscopic examination of a surface swab sample has always seemed a bit funky to me. What makes the spores and hyphal fragments stick onto the cotton swab? What prevents them from washing into the transport medium? How is the swab spun under the microscope to get a total count? I know it is done all the time but I doubt if it is ever done reproducibly.

Just a couple of comments for discussion,

Steve Temes

I am going to take an early crack at this. I know it will stimulate

discussion.

My preference is to have negative air pressurization operating until

clearance has been given. This means there is very active exchange with

outdoor air, and comparisons of indoor air to outdoor air are

straightforward (but conclusions with real data may not be). There are

certainly weather conditions when this arrangement is not appropriate,

and there are many projects that have air scrubbing only, negative air

plus air scrubbing, equipment on or off for some length of time, or none

of the above. In each case, comparisons may not be straightforward, and

the consultant generally has to use their judgment in evaluating the

results. I specify sampling from outside the building, inside the

building but outside of contained areas, and inside contained areas to

provide additional sets of potential comparisons.

My specification for post remediation verification, include the

following passages. You will note the influence from State of Texas

regulations. I will appreciate all thoughtful comments and criticisms.

Don Schaezler, Ph.D., P.E., CIH

ETC Information Services, LLC

Cibolo, Texas

Post-Remediation Activities

Post-remediation activities will include the following activities, which

will be performed by or under the on-site direction of a Licensed Mold

Assessment Consultant (MAC):

1. Containment and negative pressurization shall remain in place

until clearance has been established by the MAC.

2. The remediation areas shall be inspected for correct set-up,

operation of equipment, general cleanliness, dryness of materials, and

completion of the scope of work outlined in this Remediation Protocol,

as defined in Attachment B. If any location is determined to be

deficient, the post-remediation activities will be suspended until they

are corrected.

3. Photographs shall be taken of each remediation location in each room.

4. Sampling and analysis shall be conducted as defined in Attachment B.

5. Report on inspection and clearance activities, including

documentation of all field activities, measurements, photographs, and

sample results

Attachment B

POST REMEDIATION VERIFICATION PROCEDURES

Introduction

Remediation verification or clearance of remediation projects typically

includes the following elements:

1. Observation of the building systems to ensure that sources of

moisture intrusion or leakage have been corrected.

2. Observation of remediation methods to ensure that proper

remediation procedures have been used, and that the scope of work

completed satisfies the requirements of the Remediation Protocol.

3. Visual inspection of the work area after remediation has been

tentatively completed to ensure that there is no visible mold growth or

fungal rot, no excess dust or debris in the work area, and that surfaces

do not have excess moisture content.

4. Field measurements of temperature, relative humidity, and moisture

content of materials to ensure that conditions are consistent with

clearance of remediation of mold contamination.

5. Surface sampling to ensure that cleaning has been adequate and

that no more than background levels of fungal spores are present after

remediation.

6. Air sampling to ensure that there are no hidden reservoirs of

fungi or fungal spores and that the air has been cleaned sufficiently so

that indoor air is qualitatively similar to outdoor air.

Field Measurements - Criteria

1. Each remediation location in each room shall be measured for

moisture content using field moisture meters. Materials shall have

moisture contents less than the following:

Sheetrock: 0.5%

Wood: 15%

Concrete: 3.5%

Ceramic Tile: 3.5%

2. Each remediation area shall be sampled for temperature and

relative humidity. Relative humidity shall be less than 60%.

Clearance Protocol - Surface Samples

1. Select representative locations within the remediation areas and

collect composite surface swabs from each representative location.

2. Swabs should be handled to avoid contamination and should be used

to collect materials from at least 100 cm2 per swab. When sampling has

been completed, return swab to tube, seal with tape, mark for

identification, and package for shipment to the Licensed Mold Analysis

Laboratory.

3. There should be at least one swab for each remediation area or one

swab per 200 square feet of floor space within each remediation area.

There should be at least two swabs from similar materials in background

areas outside of remediation.

4. Submit the samples for enumeration of fungal spores and mycelial

fragments and identification of fungal spores by microscopy. The

analysis required is designated as S001 by Aerotech Laboratories, Inc.,

Phoenix, Arizona, a leading laboratory for this type of work. The

equivalent analysis by any AIHA-accredited (environmental microbiology)

laboratory, licensed by the State as a Licensed Mold Analysis

Laboratory, will be satisfactory.

5. The samples will be deemed satisfactory if any one of the

following occurs:

1. Total fungal spores are less than 10 times the detection limit for

the analysis (approximately 1 count/cm2), or

2. Total fungal spores are less than 10 times the average for the

samples from the background areas.

In addition, there must be no more than trace levels of

Aspergillus/Penicillium-like spores, Stachybotrys spores, or Chaetomium

spores.

Clearance Protocol - Air Samples

1. Collect Air-O-Cell samples from each remediation area.

2. Air-O-Cells should be handled to avoid contamination and should be

used to collect at least 75 liters of air per sample. When sampling has

been completed, seal openings, mark for identification, and package for

shipment to the Licensed Laboratory.

3. There should be at least two samples for each remediation area or

one sample for each 500 ft2 of floor space within each remediation area,

whichever is greater.

4. There should be at least two samples from outside the building for

reference.

5. There should be at least two samples from background areas inside

the building but outside of remediation, if applicable.

6. Submit the samples for enumeration of fungal spores and mycelial

fragments and identification of fungal spores by microscopy. The

analysis required is designated as A001 by Aerotech Laboratories, Inc.,

Phoenix, Arizona, a leading laboratory for this type of work. The

equivalent analysis by any AIHA-accredited (environmental microbiology)

laboratory, licensed by the State as a Licensed Mold Analysis

Laboratory, will be satisfactory.

7. The samples will be deemed satisfactory if the following occurs:

1. Within the remediation area, the average of all samples is less

than the average outdoor air value.

2. The diversity of spore population for the average of samples

within the remediation area is similar to that for the average of

outdoor air samples.

In addition, there must be no more than trace levels of Stachybotrys

spores or Chaetomium spores, unless these spores are present in outdoor air.

[Guest guest]

Don,

Nice summary of some clearance criteria. However, I have some

questions.

1. Why no culturable samples?

2. What is the justification for 200 sq.ft and 500 sq. ft ratios?

3. What is the justification for 10 times detection limit? What is the

detection limit?

4. What is the justification for averaging sampling results? Would not

areas that are dirty need to be recleaned?

5. What is the justification for 10 times the average for the

background samples?

Seems to me if the background is really dirty, this would be biased.

Bob

[Guest guest]

Bob s wrote:

> Don,

>

> Nice summary of some clearance criteria. However, I have some

> questions.

>

> 1. Why no culturable samples?

To save time and money. I think that careful inspection and surface

sampling tell you if the remediated areas are clean and dry. I have

certainly been fooled by visual observation alone. Air samples on spore

traps tell you if there is a hidden influence that should be

investigated further. In practice, air samples are often influence by

unintended sources of air infiltrating the contained area. When the area

is being scrubbed and nominally without negative air pressurization,

there are still areas of local negative air pressure that often

influence the readings. In a recent situation, it appears that outside

air was being drawn through the attic and down a fireplace chase,

influencing the room where a wall had been exposed adjacent to the chase.

> 2. What is the justification for 200 sq.ft and 500 sq. ft ratios?

Purely my judgment on reasonableness.

> 3. What is the justification for 10 times detection limit? What is the

> detection limit?

For surface samples from about 100 cm2, at Aerotech at least, the DL is

about 1 count/cm2. 10 times the DL is my opinion of a reasonable range

from ND to significantly above ND, from a general analytical point of

view. From experience with mold samples from clean surfaces, this

encompasses almost all results. Judgment can also be used.

> 4. What is the justification for averaging sampling results? Would not

> areas that are dirty need to be recleaned?

Yes, and I would not average surface samples. The reason to average air

samples is to moderate the inherent variability of the sampling and

analysis process. If two values are very far apart, I do not average the

samples, and I look in the area of the disparate sample for causes.

Again judgment can be used.

> 5. What is the justification for 10 times the average for the

> background samples?

The justification is the same as for 10 times the DL.

> Seems to me if the background is really dirty, this would be biased.

True.

>

> Bob

>

Thanks for the questions. The protocol works for me, but I will use

judgment to vary the details and assist in the interpretation.

Don

[Guest guest]

Steve:

See my comments below.

Don

AirwaysEnv@... wrote:

> Don,

>

> I like your protocol a lot. I'm not familiar with all of the TDH

> requirements that it addresses. I have two comments for discussion:

>

> 1) when I test with the negative air machine running, I have concerns

> about laminar air flow creating certain " zones " of clean make-up air

> so that the sample location in the work area is critical. I don't

> like to shut the machine off and lose negative air in the containment,

> but I prefer to let the air " homogenize " by turning the machine off

> for a brief period (5-10 minutes) to get a more " reliably

> representative " sample.

I understand the concern, and your approach seems very reasonable. What

I do is to sample near the intake of the air mover, out of the influence

of the discharge and as representative of the air in the room as any one

area could be.

>

> 2) The method of direct microscopic examination of a surface swab

> sample has always seemed a bit funky to me. What makes the spores and

> hyphal fragments stick onto the cotton swab? What prevents them from

> washing into the transport medium? How is the swab spun under the

> microscope to get a total count? I know it is done all the time but I

> doubt if it is ever done reproducibly.

I try to carefully spin the swab as I sample to roll the fragments onto

the surface. I spend significant effort getting fungal material, if

there is any, on to the swab. By contrast, I think tape samples miss

most of the fungal material from relatively clean surfaces. I understand

the liquid in the swab sample container is examined, not the swab

itself. The tube is probably mixed with a vibrator to dislodge most of

the particles, and then the liquid is transferred to a slide.

>

> Just a couple of comments for discussion,

> Steve Temes

>

[Guest guest]

Don,

Here are some other interesting questions.

What changes to your " clearance criteria " do you make for:

0. Home with a small, time limited, know water source, less than 10 sq.

ft of mold. dried in less than 4 hours.

1. Home with no symptoms.

2. Home with reported symptoms.

3. Home with medically diagnosed allergy or other symptoms.

4. Known or suspected Legal case

5. Retirement homes, day care, or other high rise known occupants.

6. Hospitals, dialysis centers, cancer treatment, centers, etc.

How do you establish the number of samples necessary to achieve

statistical significance?

Bob

[Guest guest]

Dr. s:

You make a good case for varying criteria,

particularly for know litigation. Is that not a potential disaster? Particularly

for a home where a resident has compromised immune system, or other criteria

which may lead you to hold a higher standard. If we hold that home to a higher

standard, don’t we open ourselves to series of questions? Specifically,

if testifying, and the attorney for the homeowner asks, “did you ever hold

another client’s home to a higher standard?” Then we must

honestly answer “yes.” Next question is going to be “why

would you hold someone else’s home to a higher standard than my client’s?”

P. Papageorge CIE,

CRMI, CMR

Alpha Consulting Group

Tampa, FL. 33624

www.alphaconsultingfl.com

Phone 813-514-MOLD

From: iequality [mailto:iequality ] On Behalf Of Bob s

Sent: Friday, March 17, 2006 9:27

AM

To: iequality

Subject: Re: Air

Clearance Sampling for Mould

Don,

Here are some other interesting questions.

What changes to your " clearance

criteria " do you make for:

0. Home with a small, time limited, know water

source, less than 10 sq.

ft of mold. dried in less than 4 hours.

1. Home with no symptoms.

2. Home with reported symptoms.

3. Home with medically diagnosed allergy or other

symptoms.

4. Known or suspected Legal case

5. Retirement homes, day care, or other high rise

known occupants.

6. Hospitals, dialysis centers, cancer treatment,

centers, etc.

How do you establish the number of samples

necessary to achieve

statistical significance?

Bob

[Guest guest]

After conducting a couple of thousand clearances during the great Texas mold rush and helping to author the AIHA document on Assessment, Remediation and Post-Remediation Verification of Mold in Buildings, I really must weigh in on this topic.

First, I admire the professionals that have already posted on this topic. It is one of the most contentious of issues in the field I think because it decides when the job is done and the money is paid, so there has been much designing done by some around how to pass and by others on how to fail.

2. There has been a lot of non-science and science applied in the field, and some of both has become standard practice. It is good to remember that just because something is codified into law (hello, Texas) doesn't mean that it isn't nonsense from a science perspective.

3. While professionals should apply profession judgment, persons that need to know how to assemble a big mac or otherwise need a cookbook approach to an otherwise technical process should consider the following:

a. Use tape samples during PRV only to validate what your eyes see. If you can see mold, its not OK, and you should take a tape sample so you can have another piece of data to bolster your position that it is not OK. If you cannot see mold on a surface, that surface is OK (again this advice is for Texas Licensed Mold Assessors and other big mac assemblers, and not for hospital nosocomial work, etc where somebody would be negligent for hiring without knowledge of such nuances).

b. Regarding air movers, the remediator should disable the neg air and continue to scrub the air inside of containment for an adequate period (the night before the clearance?). When the TLMA gets to the jobsite, shut off the neg air and wait X minutes (some of you can calculate the settling rate of the more than 10 micron particles; hurray for the science guys!). This will allow you to actually measure much more accurately for all parties involved the actual concentration of spores with 75L through an AOC.

c. If you are anywhere near the Gulf Coast, a trace quantity of a couple of Stachy spores in your samples is nothing but background. Read my paper presented at Indoor Air 2002 and get a good nights sleep.

d. Be sure and focus some of your attention and sampling on adjacent areas. Lots of neg air machine have been hooked up backwards during remediation by, well, mold remediation workers that I would not trust to assemble a big mac.

Of course there are many many more issues, but sometimes its good to keep things simple, even if it does offend the sciences. And my apologies in advance to Mcs Corporation for the perhaps inappropriate analogy, including a nod from me to others that flipped a few hamburgers to get themselves through college.

B. Dotson, CIH, CSP San , CAemail: kyle@...

-----Original Message-----From: iequality [mailto:iequality ] On Behalf Of ASISH MOHAPATRASent: Tuesday, March 14, 2006 12:57 PMTo: iequality Subject: Air Clearance Sampling for Mould

Hi all:

I have a question for the group.

Should HEPA Air Scrubbers be turned On or Off During Air Clearance Sampling for mold? What are the pros and cons?

I did a quick search on "Google". The first hit I got is a book from Safety-EPA.com.

Bob, is this your book? "Post-Remediation Verification (PRV) of Mold / Bacteria Remediation Projects - Risk-Based Levels of Cleanliness Standards".

Sincerely,

Ash

Bob s wrote:

The 6th Edition of Worldwide Standards for Mold and Bacteria is finally back from the printer. This edition is a major expansion of the book with 30 more pages. Now 119 pages!The additions include:1. Adjustment to the AAAAI table to account for 5 minute AOC samples vs 24 hour Burhart samples and nighttime vs. daytime sporulator bias. (ref. Lei and Kendricks.)2. Bacteria standards for 18 different environments.3. The German Baubiology standards.4. More Poland bacteria standards,5. More information on the Hesse sampling tube that sampled for viable mold and bacteria at the same time.6. More historical information on bacteria and mold levels in housing, schools and hospitals and the first mold and bacteria "air purity" standard.7. Comprehensive index.Bob

Yahoo! MailUse Photomail to share photos without annoying attachments.

[Guest guest]

,

Your question about varying criteria is not how I approach this

question.

We deal with this as increasing levels of verification of cleanliness.

It is always assumed that the area is clean. It is just how

confident and how much evidence you want to have to prove that it is

clean.

That is why we call them different " levels of cleanliness assurance "

not different cleanliness levels.

Clearly, you would want more evidence of cleanliness in a legal case or

an immuno compromised situation than in a case of non symptomatic home.

In a hospital one would want more evidence of cleanliness assurance

than in situation of a home with only adults an no children or people

over 65.

It really comes down to more risk = more samples to be taken.

We will be presenting this at AIHA in a 90 minute lecture on Monday.

Bob