The Fallacy of Asbestos Clearance Air Sampling, or 5 Reasons Why We Should Stop Using Phase Contrast Microscopy for Clearance.

The Environmental Protection Agency's (EPA's) Asbestos Hazard Emergency Response Act (AHERA) regulation introduced the requirement of clearance sampling after an asbestos abatement project was completed.  The AHERA regulation applies to schools from Kindergarten to 12th grade (K-12), both public and private schools.  However, for all intents and purposes, the AHERA method of clearance serves as the industry standard when final clearance is performed for most asbestos abatement projects, especially when areas are to be re-occupied.  The requirements for clearance are found in two sections of the rule:

• Response Actions; §763.90 (i)
• Appendix A (to Subpart E) - Interim Transmission Electron Microscopy Analytical Methods - Mandatory and NonMandatory - and Mandatory Section to Determine Completion of Response Actions

AHERA allows final clearance air sampling to be done by phase contrast microscopy (PCM) methodology for projects less than or equal to 160 square feet (SF) or 260 linear feet (LF) by the National Institute for Occupational Safety and Health (NIOSH) 7400 methodology (Issue 3: 14 June 2019 is the current issue).  For projects greater than 160 SF or 260 LF clearance shall be done by the AHERA transmission electron microscopy (TEM) method (requirements at 763.90 (i) (4) and Appendix A).  Since this article's purpose is to discuss why we should not be using the PCM method we will focus our discussion on this method specifically.  An important point to remember is that the method was designed for personal sampling of workers in environments with actual asbestos exposures.  AHERA adapted the method for clearance requiring that each sample must be less than or equal to a limit of quantitation (LOQ) for PCM of 0.01 fibers per cubic centimeter (f/cc).

Over the years, it has become abundantly clear that the PCM method should not be used for clearance sampling.  The top five reasons it should not be used for clearance sampling are:

Size of the Fibers Analyzed

The rules for the NIOSH 7400 method specifically require the microscopist to count only fibers that are greater than 5 micrometers (microns) length.  When it comes to diameter it is questionable whether fibers less than 0.25 microns in diameter can or cannot be detected by the method.  All other fiber lengths and narrow widths are not counted they are too thin with normal PCM resolution.  At the Professional Abatement Contractors of New York 2023 Environmental Conference, Lee Poye, Vice President Emeritus, Eurofins Built Environment, discussed his presentation "Asbestos in Human Tissue and the Environment - Does Size Matter?"

Lee Poye Presenting at PACNY 2023

According to his presentation, in an article titled "Short, Fine, and WHO Asbestos Fibers in the Lungs of Quebec Workers With an Asbestos-Related Disease" by G. Adib, F. Labreche, L. DeGuire, C. Dion, & A. Dufresne and published in the American Journal of Industrial Medicine in 2013 the type of fibers that are seen in diseased tissue are less than 5 microns and less than 0.25 microns in width.

 

Lee Poye Presenting at PACNY 2023

Mr. Lee Poye's own research (not published) found a similar finding see below.  Based on his presentation, we know that size does matter regarding diseased human tissue.  Mr. Poye's conclusion from his presentation were:

• What's the skinniest PCM fiber a "typical AMT" can see? 0.18 micron.
• Just how much chrysotile is missed by PCM? Almost ALL of it!
• What % of chrysotile fibers detected in human tissue would've been visible by PCM?  Maybe 2% to 3% at best!

Lee Poye's Own Research at PACNY 2023 

Considering between 98-99% of the chrysotile fibers that are seen in the tissue of diseased lungs are not seen by the PCM method.  Why are we using a method that does not detect the fibers that actually cause disease for clearance?

Is the Work Area Actually Clean?

In 2003, Applied Occupational and Environmental Hygiene published a study called "Asbestos Release During Removal of Resilient Floor Covering Materials by Recommended Work Practices of the Resilient Floor Covering Institute" by Marion Glenn Williams, Jr. and Robert N. Crossman, Jr. from the University of Texas Health Center at Tyler, Tyler Texas.  The major points from this study were:

• Asbestos used in flooring materials is Grade 7 - Shorts and Floats.  The dimensions of this material are very small and may not be resolvable by the Polarized Light Microscope (PLM).  This is why New York State Environmental Laboratory Approval Program (NYS ELAP) requires floor tiles to be analyzed as a nonfriable organically bound (NOB) material (analysis by PLM and if negative result for asbestos, then analysis by TEM).
• Many research studies have found the preponderance of fibers at autopsy left in lung tissue, pleural plaques, and lymph nodes of persons who have occupational asbestos exposure are shorter than 5 microns in length.
• The NIOSH 7402 TEM method is flawed because it underreports the amount of asbestos in the samples because it ignores all fibers less than or equal to 5 microns and all those fibers longer than 5 microns but less than 0.25 micron in diameter.
• AHERA TEM method counts for total asbestos structures per cubic centimeter averaged 22 times greater than the PCM fiber counts on the same filters.
• AHERA TEM asbestos concentrations obtained during mastic removal with a commercial mastic remover averaged 11 times higher than those measured when removal used amended water.
• The study also found that there was considerable amounts of asbestos dust settled on exposed surfaces during tile removal.  Indicating a need to thoroughly HEPA vacuum and wet clean surfaces or dust may remain that could be re-entrained by occupant activity.
• The study also indicates that workers in these areas, would not have to wear respirators, so anyone in these areas would have inhaled asbestos fibers or structures of respirable dimensions.

At the 2017 PACNY Environmental Conference a debate occurred about our call for TEM clearance sampling for all asbestos floor tile projects based on the above study.  This debate led to our writing the article Asbestos Floor Tile Debate Results Post and our article in Healthy Buildings.  Our major points were:

• When using the AHERA TEM method for clearance, what was the typical size of the fibers found?  The answers we got were 58.8% less than 5 microns; 29.4% of both sizes were equal amounts; and 11.8% greater than 5 microns.
• Have you ever encountered during asbestos flooring removal when utilizing both the NIOSH 7400 (PCM) & the AHERA (TEM) methods of analyses, that the NIOSH 7400 passed while the AHERA TEM method failed?  The answers we got were 52.6% yes, 36.8% no, and 10.5% never used both.
• AHERA TEM method counts for total asbestos structures per cubic centimeter averaged 22 times greater than the PCM fiber counts on the same filters.

• AHERA TEM asbestos concentrations obtained during mastic removal with a commercial mastic remover averaged 11 times higher than those measured when removal used amended water.

At the 2020 PACNY Environmental Conference – Jack Snider, III CSP LAC, GC of AMRC presented on Take-Home Asbestos Exposure. During the removal of floor tile, mastic, and other non-friable ACM, workers are typically wearing street clothes into the work area, and they are not showering nor vacuuming themselves/their clothing upon exiting the containment.  

Mr. Snider's presentation found workers performing floor tile projects had significant Take-Home Asbestos Exposure.  These points all bring up the question of whether the work area is actually clean when we use the PCM method.  Many building abatement projects are passing by PCM that would not pass clearance by TEM.  

Is 0.01 fibers/cubic centimeter (f/cc) Safe?

Well based on the World Health Organization (WHO), and the EPA there is no safe level of exposure.  If we look at how many asbestos fibers we are breathing in at 0.01 f/cc if we were making a moderate effort it would be approximately 100 asbestos fibers per minute or for an 8-hour day it would be 48,000 asbestos fibers.  If we look at the amount of asbestos fibers in a cubic foot of space it would be 283 asbestos fibers/CF.  So what is the risk at 0.01 f/cc?  In 2021, the Committee for Risk Assessment (RAC) prepared an expert opinion for the European Chemical Agency (ECHA) on the scientific evaluation of occupational exposure limits for asbestos. They have concluded that there is no “safe” level of asbestos exposure. Instead, they provided an exposure-risk relationship to express the excess risk of cancer at different levels of asbestos exposure.  According to the RAC, the risk of excess lifetime cancer risks is 12 cases per 100,000 exposed at 0.01 f/cc. 

Compare that risk with the following, in 2022, 1,069 construction professionals died while working, a rate of 9.6 fatalities per 100,000 full-time workers, according to a report by the Bureau of Labor Statistics.  That fatality rate was the third highest, behind agriculture, forestry, fishing and hunting (18.6 per 100,000) and transportation and warehousing (14.1 per 100,000).  Realize the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) is 0.1 f/cc based on an 8-hour time-weighted average (TWA) and according the RAC that risk is 125 per 100,000 exposed.

Industry, occupation, and exposure history of mesothelioma patients in the U.S. National Mesothelioma Virtual Bank, 2006–2022 found these points:

• Among the 1023 industries recorded for those having mesothelioma, the most frequent cases were found for those in manufacturing (n = 225, 22.0%), construction (138, 13.5%), and education services (66, 6.5%)….
• Males (583) or persons aged >40 years (658) at the time of diagnosis tended to have worked in industries traditionally associated with mesothelioma (e.g., construction), while females (163) or persons aged 20–40 years (27) tended to have worked in industries not traditionally associated with mesothelioma (e.g., health care). 

Malignant Mesothelioma Mortality — United States, 1999–2015 Weekly / March 3, 2017 / 66(8);214–218 Jacek M. Mazurek, MD, PhD1; Girija Syamlal, MBBS1; John M. Wood, MS1; Scott A. Hendricks, MS2; Ainsley Weston, PhD1 found:

• Current occupational exposure occurs predominantly during maintenance and remediation of asbestos-containing buildings.
• Continuing occurrence of malignant mesothelioma deaths in persons aged <55 years suggests ongoing inhalation exposure to asbestos fibers and possibly other causative EMPs.

The above table is from the above referenced material.  However, we have added the last column based on a 30-year latency period which gives an interesting perspective based on when the person most likely was exposed to asbestos.  Consider that over 650 individuals were most likely exposed before working age.  this could result from exposures due to take-home exposure, do-it-yourself projects, or from attending schools that are not managing asbestos properly.  It is also interesting to note that the number of mesothelioma deaths between 1999-2015 has remained roughly the same, between 2479-2873 individuals. 

Based on all this information a better clearance level would be 0.001 f/cc and a better occupational exposure limit would be 0.01 f/cc or 0.005 f/cc as an 8-hour TWA.  In November 2023, the European Union has adopted a reduction of the exposure limit for workers to 0.01 f/cc as an 8-hour TWA and after a maximum transition period of six years, member states will have to switch to electron microscopy.  In addition, in the EPA's chrysotile asbestos ban beginning November 5, 2024,....no person is exposed to an airborne concentration of chrysotile asbestos in excess...0.005 fibers per cubic centimeter (f/cc) as an 8-hour time-weighted average (TWA).  Considering all of this it is obvious 0.01 f/cc is not an appropriate level for clearance.  Utilizing TEM for clearance would ensure we are achieving the lowest protective level possible.

Are We Sampling Correctly?

In our blog post The Reality of Asbestos Clearance Air Sampling! Are You Sampling Enough? and our article in Healthy Buildings "You Can't Handle The Truth....About Clearance Sampling."  The major points from these articles were:

• Many believe or have been misled to believe that PCM sampling is the same as TEM sampling in terms of sampling volume.  This is not the case.  A PCM sample volume meeting AHERA clearance requirements are not at 1200 liters.  To do so is outside of the NIOSH 7400 method requirements for this purpose.  Even others have used the limit of detection sample volume to collect 560 liters.  
• In the NIOSH 7400 method, the issue regarding "relatively clean" environments" is addressed on page 4, number 4, note number 1 which states  "In relatively clean atmospheres, where targeted fiber concentrations are much less than 0.1 f/cc, use larger sample volumes (3000 to 10,000 liters) to achieve quantifiable loadings."
• Even though the formula calculates that 3,850 liters of air should be collected, many people use note 1 to collect 3,000 liters of air for clearance.  Either way clearance samples should be collected using no less than 3,000 liters of air as the minimum allowed for the NIOSH 7400 method requirements and AHERA compliance. 

Airbox Calibration Setup

In New York State the recommended sampling volume is 1,200 liters of air (based on the NYSDOH ELAP and the Bureau of Occupational Health and the New York State Department of Labor (NYSDOL) FAQ#13) and in the New York City Department of Environmental Protection (NYCDEP) Title 15 the required sampling volume is 1,800 liters of air for PCM clearance.  Based on the LOQ formula what are the consequences of not collecting the required volume?  Remember this is a formula and if you modify the formula to solve for L instead of t.  You then plug in the amount of time you're actually sampling for then you get the actual result you are achieving.

The NIOSH 7400 method, utilizes the formula above to determine the amount of time needed to achieve the fiber density, E, for optimum filter loading.  So, the minimum density the method allows is 100 fibers per square millimeter (mm²).  The Ac is the collection area for a 25-mm cassette which is 385 mm².  The Q is the sampling flow rate in LPM, and t is the time we are collecting the sample.  Modifying the formula to calculate for L or the LOQ concentration, we get this for 560 liters.

When using 1200 liters we get the following:

When using 1800 liters we get the following:

The consequences of the above numbers are that the:

• EPA AHERA clearance requirement of less than or equal to 0.01 f/cc is not being met. 
• NYSDOL Industrial Code Rule 56 (ICR56) clearance requirement of less than 0.01 f/cc is not being met.
• NYCDEP Title 15 clearance requirement of less than 0.01 f/cc is not being met

According to the RAC, the risk of excess lifetime cancer risks is 25 cases per 100,000 exposed at 0.02 f/cc and somewhere between 25 and 65 cases per 100,000 exposed at 0.03 f/cc.

At the 2024 Environmental Information Association (EIA) National Conference & Exhibition we conducted a survey of the attendees regarding the volume of air they collected for PCM clearance.  Below are the results:

As you can see from the results none of the individuals that answered the question are actually collecting the correct volume of air required by the NIOSH 7400 methodology.  Improper collection of PCM samples is not meeting the clearance requirements.

The Cost of Clearance Sampling

We know what you are going to say TEM samples cost way more than PCM samples.  We agree they do, but not compared to when AHERA first came out.  When AHERA first came out there were hardly any laboratories that did TEM analysis and those that did the samples cost between $350-500 per sample.  The difference between PCM analysis costs and TEM analysis costs has come way down.  A recent quote we received from a reputable laboratory for PCM analysis with a 3-hour turnaround was $12.50 per sample while TEM AHERA analysis with a 4-hour turnaround was $150 per sample.  The price difference is smaller than it once was. The odd math is that the difference in price between PCM and TEM for many projects is not even a rounding error to the overall budget, where the total construction budget could be in the millions (renovations). 

If PCM cannot see the fibers that cause disease or even determine that the area is clean, is it worth the money or the paper it is printed on when it comes to final clearance air sampling? 

TEM should be the only method employed for clearance air sampling!

Chrysotile Asbestos Banned? More Like Certain Conditions of Use Will Be Eventually Banned!

Many of you, as did I, read about the "Ban of Chrysotile Asbestos" and rejoiced over something long overdue.  However, after reading this so-called ban it is obvious that it is not a ban.  Just reading the title of the rule tells you it is not a ban. "Asbestos Part 1 - Chrysotile Asbestos; Regulation of Certain Conditions of Use Under the Toxic Substances Control Act (TSCA)".  This rule is only regulating "certain conditions of use".  We would say the media needs a dictionary if they actually think after reading the title this is a ban.  What is the definition of a ban?  Ban is to prohibit or forbid especially by legal means (as by statute or order).  After reading the rule, it is obvious this is not banning all uses of chrysotile asbestos, but banning or restricting its use in very specific industries.  In addition, what about the other types of asbestos: amosite, crocidolite, tremolite, anthophyllite, actinolite, or the Libby amphiboles?  No mention of these there!

Since this is not a ban and 40,000 Americans die annually from asbestos-caused diseases it is even more important that we Tell Congress to Ban Asbestos!  The Asbestos Disease Awareness Organization (ADAO) has developed a coalition of firefighters, public health, and safety officials who are calling on the public’s support in their decades-long fight to convince the U.S. Congress to ban deadly asbestos.  Now, you have an opportunity to write your own message to US Senators and US Representatives to ask them to support the Alan Reinstein Ban Asbestos Now Act (ARBAN). This act would prohibit the manufacture, processing, use, and distribution of commercial asbestos in commerce - a known carcinogen that is still widely in use across the U.S. Make your voice heard on this link. It takes only a minute.

Chrysotile Asbestos

Before we go into this rule, let's remember we still have the Significant New Use Rule (SNUR) that came out on April 25, 2019.  This rule did not ban any forms of asbestos but allowed manufacturers (including importing), or processors of asbestos (including as part of an article) to seek permission from the Environmental Protection Agency (EPA) for the significant new use (it included a list of uses that would need permission).

The final rule can be found on EPA's website here.  The document consists of 40 pages (pages 21970 to 22010).  However, the rule is found on page 22005 (35 pages after the beginning of the document, meaning the rule consists of only 5 pages).  Subpart F - Chrysotile Asbestos starts with the different Sections of the Rule:

• 751.501 General
• 751.503 Definitions
• 751.505 Manufacturing, processing and commercial use of chrysotile asbestos diaphragms in the chlor-alkali industry. 
• 751.507 Certification of compliance for the chlor-alkali industry. 
• 751.509 Other prohibitions and restrictions of the manufacturing, processing and commercial use of chrysotile asbestos. 
• 751.511 Interim workplace controls of asbestos exposures. 
• 751.513 Disposal. 
• 751.515 Recordkeeping. 

As you can see from this list, these are the Certain Conditions of Use.  Let's look at 751.505 diaphragms (means semipermeable diaphragms, which separate the anode from the cathode chemicals in the production of chlorine and sodium hydroxide (caustic soda).  

• Section (a) states, after May 28, 2024, all persons are prohibited from manufacture (including import) of chrysotile asbestos, including any chrysotile asbestos-containing products or articles, for diaphragms in the chlor-alkali industry.  

That is a ban on the import of chrysotile asbestos, but only for diaphragms, however, the next section is on the use of diaphragms containing chrysotile asbestos, 

• Section (b) states, after May 28, 2029, all persons are prohibited from processing, distribution in commerce, and commercial use of chrysotile asbestos, including any chrysotile asbestos-containing products or articles, for diaphragms in the chlor- alkali industry, except as provided in paragraphs (c) through (d) of this section. 

Here is the devil in the details:

• Section (c) Any person who meets all of the criteria of this paragraph (c) may process, distribute in commerce and commercially use chrysotile asbestos, including any chrysotile asbestos- containing products or articles, for diaphragms in the chlor-alkali industry at no more than two facilities until May 25, 2032: (1) On May 28, 2024, the person owns or operates more than one facility that uses chrysotile asbestos in chlor-alkali production; (2) The person is converting more than one facility that the person owns or operates that as of May 28, 2024 uses chrysotile asbestos in chlor-alkali production from the use of chrysotile asbestos diaphragms to non-chrysotile asbestos membrane technology, and by May 28, 2029, the person has ceased all processing, distribution in commerce and commercial use of chrysotile asbestos at one (or more) facility undergoing or that has undergone conversion to non-chrysotile asbestos membrane technology; and (3) The person certifies to EPA compliance with the provisions of this paragraph, in accordance with §751.507. 
• (d) Any person who meets all of the criteria of this paragraph (d) may process, distribute in commerce and commercially use chrysotile asbestos, including any chrysotile asbestos- containing products or articles, for diaphragms in the chlor-alkali industry at not more than one facility until May 26, 2036: (1) On May 28, 2024, the person owns or operates more than two facilities that use chrysotile asbestos in chlor-alkali production; and (2) The person is converting more than two facilities that the person owns or operates that as of May 28, 2024 use chrysotile asbestos in chlor-alkali production from the use of chrysotile asbestos diaphragms to non-chrysotile asbestos membrane technology: (i) By May 28, 2029, the person has ceased all processing, distribution in commerce and commercial use of chrysotile asbestos at one (or more) facility undergoing or that has undergone such conversion; and (ii) By May 25, 2032 the person has ceased all processing, distribution in commerce and commercial use of chrysotile asbestos at two (or more) facilities undergoing or that have undergone conversion to non-chrysotile asbestos membrane technology; and (3) The person certifies to EPA compliance with the provisions of this paragraph, in accordance with §751.507. 

So other words we have a ban on the manufacture/importing of chrysotile asbestos to make diaphragms but the use of chrysotile asbestos diaphragms is not banned until 2036.  In addition, 751.509  Other prohibitions and restrictions of the manufacturing, processing, and commercial use of chrysotile asbestos covers:

• Prohibit the manufacture (including import), processing, use, distribution in commerce and commercial use of chrysotile asbestos, including any chrysotile asbestos-containing products or articles, for sheet gaskets in chemical production and require interim workplace controls for certain commercial uses after May 27, 2026.  With exceptions for titanium dioxide production until May 28, 2029, and processing nuclear material at the Savannah River Site until December 31, 2037. 
• Prohibit the manufacture (including import), processing, distribution in commerce, and commercial use of chrysotile asbestos, including any chrysotile asbestos-containing products or articles, for oilfield brake blocks, aftermarket automotive brakes, and linings, other vehicle friction products, and other gaskets after November 25, 2024; 
• Prohibit the manufacture (including import), processing, and distribution in commerce of chrysotile asbestos, including any chrysotile asbestos-containing products or articles, for consumer use of aftermarket automotive brakes and linings and other gaskets after November 25, 2024.
• All of these have exceptions to the distribution in commerce prohibition if they are already installed.

https://www.asbestos.com/occupations/auto-mechanics/

Section 751.511 Interim workplace controls of asbestos exposures is an interesting section considering it's stepping on the toes of the Occupational Safety and Health Administration (OSHA).  This section applies to the processing, and commercial use of chrysotile asbestos, including any chrysotile asbestos-containing products or articles, for chrysotile asbestos diaphragms in the chlor-alkali industry; and to the commercial use of chrysotile asbestos sheet gaskets for titanium dioxide production.   The section establishes an exposure limit called the Interim Existing Chemical Exposure Limit (ECEL):

• Beginning November 5, 2024,....no person is exposed to an airborne concentration of chrysotile asbestos in excess...0.005 fibers per cubic centimeter (f/cc) as an 8-hour time-weighted average (TWA).  Remember the OSHA Permissible Exposure Limit for asbestos is 0.1 f/cc as an 8-hour time weighted average.  The ECEL is a 20 times reduction from the PEL.
• Requires initial (performed as of May 28, 2024, and no later than November 25, 2024) & periodic exposure monitoring (performed within three months or six months based on previous results).
• Method of Monitoring utilizes OSHA 1910.1001 Appendix A, OSHA method ID-160, or the National Institute of Occupational Safety and Health (NIOSH) 7400 method.  Allowance for the NIOSH 7402 method to adjust the analytical result to include only chrysotile asbestos. 

Personal Sampling Pump

The section also includes additional requirements for exposure monitoring, establishing regulated areas, exposure control procedures, respiratory protection, and workplace information and training.  The respirator section makes for interesting reading for those who know the OSHA respiratory protection standard.  Below are some examples of the respirator requirements:

• If exposure monitoring indicates the exposure is above 0.00view 5 f/cc and less than or equal to 0.05 f/cc.  The employer must provide either a half-mask supplied air (SAR) or airline respirator operated in demand mode or a half-mask self-contained breathing apparatus (SCBA) respirator operated in demand mode.
• If exposure monitoring indicates the exposure is above 0.05 f/cc and less than or equal to 0.125 f/cc.  The employer must provide a loose-fitting facepiece supplied air (SAR) or airline respirator operated in continuous flow mode.

Supplied airline respirator

It is obvious from these respirator selections EPA is reaffirming that there is no safe exposure level to asbestos.  For those of us who remember the EPA's and NIOSH's White Book "A Guide to Respiratory Protection for the Asbestos Abatement Industry", remember that this quote was in that book:

"Respirators which use filters to remove contaminants from the air do not provide as high a degree of protection for workers as respirators which supply clean pressurized air to the workers from a protected source."

Realize these restrictions are stricter than OSHA requirements and we wonder what this means for Part 2 of this evaluation process when EPA will be looking at Legacy issues?

Related articles

• The National Law Review - EPA Bans Ongoing Uses of Asbestos https://www.natlawreview.com/article/epa-bans-ongoing-uses-asbestos
• ADAO's FAQs and Quotes on EPA Part 1 Chrysotile Asbestos Rule
   https://www.asbestosdiseaseawareness.org/newsroom/blogs/faqs-and-quotes-on-epa-part-1-chrysotile-asbestos-rule/

Two Guys Talking About Pumps

Future Environment Designs Training Center (FEDTC) in our August 2022 Safety Suzy Newsletter and our August 29th blog post announced that the International Sales Director of FermionX, Dan Crothers was attending our September 19, 2022, Project Sample Technician/Project Monitor Refresher course.  FermionX, Ltd. is a UK electronics manufacturer of industrial product brands including the Airbox Sampling Pumps.   

Airbox Sampling Pump

Mr. Dan Crothers demonstrated the features of the AirBox pumps in our courses.  Those who attended the courses were introduced to the equipment, and how it operates.  We discussed the various features, advantages, and disadvantages of using this new pump.  Two of our clients who attend our courses The LIRO Group and New York Environmental Consultants & Laboratories ended up walking away with an Airbox sampling pump to try in the field.  While Mr. Dan Crothers was here he recorded a video discussing asbestos air sampling pumps with Angelo Garcia, III, and what makes this pump a game changer.  The video will be shown in our future asbestos classes or you can see it below:

If you are interested in more information feel free to contact us.

The Reality of Asbestos Clearance Air Sampling! Are You Sampling Enough?

We attended the Environmental Information Association (EIA) 2022 National Conference and Exhibition in Phoenix, Arizona from March 20, through March 23, 2022.  We attended several sessions regarding asbestos where we discussed with some attendees asbestos clearance air sampling and what are the Federal requirements.  Based on those discussions we figured it was time to write an article on this topic.  To make sure we wrote this article based on general industry practice, versus what we are used to in New York State and New York City, we consulted with Mr. Tom Laubenthal, of TGL Consulting, Inc., and Mr. Dana Brown, of Time's Dark Captains.  Since everything else seems to start with the Environmental Protection Agency's (EPA's) Asbestos-Containing Materials in Schools Rule (40 CFR Part 763, Subpart E, known in the industry as the Asbestos Hazard Emergency Response Act (AHERA)) why don't we start there?  The AHERA regulation remember applies to schools from Kindergarten to 12th grade (K-12), both public and private schools.  The requirements are found in two sections of the rule:

• Response Actions; §763.90 (i)
• Appendix A (to Subpart E) - Interim Transmission Electron Microscopy Analytical Methods - Mandatory and NonMandatory - and Mandatory Section to Determine Completion of Response Actions

For all intents and purposes, these methods serve as the industry standard when final clearance is performed for most asbestos abatement projects, especially when areas are to be re-occupied. We’ll discuss applicability issues as we go. 

TEM Analysis

First, let's discuss the requirement for aggressive clearance sampling.  In the AHERA regulation, aggressive sampling means floors, ceilings, and walls shall be swept with the exhaust of a minimum one (1) horsepower leaf blower.  Some states and specifications may also require the use of fans as described in the non-mandatory section of Appendix A.  The non-mandatory section states, that stationary fans shall be placed in locations that will not interfere with the air monitoring equipment.  Fan air is directed toward the ceiling.  One fan shall be used for every 10,000 cubic feet (CF) of a worksite.  This is required in the New York State Department of Labor's Asbestos Regulation Industrial Code Rule 56 (NYSDOL ICR56) and the New York City Department of Environmental Protection Asbestos Regulation Title 15 (NYCDEP Title 15).  However, NYSDOL ICR56 also requires one fan per room in addition to the one fan per 10,000 CF.

This is not in the spirit of the AHERA/NYSDOL ICR56/NYCDEP Title 15 requirements for aggressive clearance sampling. Thank you Greg Mance for the photo.

As defined by the AHERA rules, final clearance air sampling can be done by phase contrast microscopy (PCM) methodology for projects less than or equal to 160 square feet (SF) or 260 linear feet (LF) by the National Institute for Occupational Safety and Health (NIOSH) 7400 methodology (Issue 3: 14 June 2019 is the current issue).  For projects greater than 160 SF or 260 LF clearance shall be done by the AHERA transmission electron microscopy (TEM) method (requirements at 763.90 (i) (4) and Appendix A).

Graphic courtesy Tom Laubenthal

There are some similarities between the AHERA TEM and NIOSH 7400 methods.  For example, the AHERA TEM method (Appendix A) allows for the use of either a 25-millimeter (mm) filter cassette or a 37-mm filter cassette.  We haven't used a 37-mm cassette since the industry switched from the old asbestos sampling method NIOSH P&CAM 239 to the NIOSH 7400 method that was formally adopted into AHERA.  For sampling, whether it is the AHERA TEM method or the NIOSH 7400 method, we use a 25-mm 3-piece cassette with 50-mm electrically conductive extension cowl cassettes.  The two methods require the filter cassette to face 45 degrees downward from the horizontal.  The filter material used is mixed cellulose ester (MCE).  AHERA TEM method does allow for the use of polycarbonate (PC) filters as well.  The PC filters fell out of favor because post-sampling handling was more problematic than the MCE filters.  With PC filters, if samples sent to the lab are not handled carefully, the sampled fibers can move significantly from the filter surface.  This was widely discussed in the industry in the 1980s.  Since then, only MCE filters are used outside of specialty applications. 

The filter cassette is to face 45 degrees downward from the horizontal.

Both methods require blanks, however, that is where the similarities end.  The AHERA TEM method requires three blanks two field blanks and one laboratory (sealed) blank.  While the NIOSH 7400 method requires a minimum of two blanks or 10% of samples collected with a maximum of 10 blanks.  How the blanks are handled is different as well. The AHERA TEM method laboratory (sealed) blank is not opened and kept sealed, while the field blanks are opened for 30 seconds at the entrance to each abatement area and one at an ambient area.  While the NIOSH 7400 method requires the blanks to be opened at the same time as the other cassettes just prior to sampling and stored with the top covers of the cassettes that are running and remain open for the duration of sampling (here is an interesting difference, in some places the cassettes are stored in the box with the lid closed or, the way we were taught, they are placed in a Ziploc bag that is used to deliver the samples to the laboratory).  

A typical box of air sampling cassettes

Another difference is that with the AHERA TEM method we use a 0.45-micron (µm) MCE filter and the NIOSH 7400 method uses a 0.8 µm MCE filter.  This refers to the size of the air passages in the filter material. Filter manufacturers will color code or mark the label so that the type of filter within the cassette assembly is known to the user and the laboratory.

TEM filter is 0.45-micron.  PCM filter is 0.8-micron.

Let's get to some of the interesting items such as how the samples are taken and how many are required.  The AHERA TEM method is straightforward, it requires 5 samples inside the work area and 5 samples outside the work area that represent air entering the abatement site plus the blanks (as mentioned above) for a total of 13 samples.  These samples should run from 1 to less than 10 liters per minute (LPM) for a total volume of air greater than 1199 liters or greater (see Table 1 below for the recommended sampling volume range for this method, typically the volume range is between 1200 liters and 1800 liters).  It is interesting that the maximum flow rate is less than 10 LPM.  It would be interesting to find out how many in the industry actually sample at less than 10 LPM (i.e., 9.9 LPM versus 10 LPM).  Likely most of the industry merely samples at 10 LPM.  The statistical difference between 10 and 9.9 LPM, some regulators insist upon, is statistically insignificant and will affect method performance in no discernable manner.  Either way, this means your clearance samples will take a little over 2 hours to collect.  

In speaking with Mr. Tom Laubenthal, we learned at the time this method was developed it became known through the research involved that flow rates higher than 10 LPM could cause fibers to impact the MCE filters vertically and not horizontally to the filter surface.  This makes the sample analysis, counting, and identification, difficult and likely biased.  This is also the reason the method specifies a second MCE filter under the 0.45 µm sampling filter and the 5 µm diffuser. This additional filter is placed in this manner to attempt to create an even flow across the filter surface so that fibers impact the filter uniformly.  Since the fibers are lying flat on the filter this is the reason for turning the sample upright before interrupting the pump flow to ensure the fibers remain on the filter.

Sampling Cassette Configuration

In the AHERA TEM method, the clearance samples pass when the average concentration of the five samples inside the work area does not exceed 70 structures per square millimeter (s/mm²).  See AHERA at 763.90 (i) (3) for an optional clearance test based on the z-test which compares the outside and inside air samples.  This is rarely necessary.  But cases have occurred when contamination can exist in the air outside the work area that could cause a failure in the work area.

This TEM asbestos image is from the Centers for Disease Control (CDC) "Asbestos Fibers and Other Elongate Mineral Particles: State of the Science and Roadmap for Research"

The NIOSH 7400 method for final clearance is also interesting when it comes to how the sample is taken and how many are based on the project.  For schools, when PCM is allowed, it's 5 samples inside the work area.  What's interesting is that the clearance is based on each sample and each sample must be less than or equal to a limit of quantitation (LOQ) for PCM of 0.01 fibers per cubic centimeter (f/cc).  Well according to the NIOSH 7400 method how do you achieve clearance at that LOQ?  This concept of LOQ is not a concept understood by many that use the NIOSH 7400 method for all its purposes.  In the NIOSH 7400 method, this issue is addressed as follows in the section "Sampling", number 4 on page 4.  It utilizes the formula below to determine the amount of time needed to achieve the fiber density, E, for optimum filter loading.  So, the minimum density the method allows is 100 fibers per square millimeter (mm²).  The Ac is the collection area for a 25-mm cassette which is 385 mm².  The Q is the sampling flow rate in LPM, so let's say that is 16 (the maximum flow rate allowed by the method).  The L is the concentration of fibers in the air, we are looking to achieve clearance at 0.01 fibers/cubic centimeters (f/cc).  So if you plug these numbers into the formula you get a time of 240.6 minutes, which means the sample would have to run for a little over 4 hours at 16 liters per minute (total volume of air of 3,850 liters).

Realize that is running the sample at 16 LPM.  If your pump/flowmeter can only go to 15 LPM then you would have to run the sample for 256.7 minutes which is just short of 4 hours and 15 minutes.  The lower the flow rate, the longer time it will take to meet sample volume requirements. 

Airbox High-Performance Air Sampler

Many believe or have been misled to believe that PCM sampling is the same as TEM sampling in terms of sampling volume.  This is not the case.  A PCM sample volume meeting AHERA clearance requirements are not at 1200 liters.  To do so is outside of the NIOSH 7400 method requirements for this purpose.  In the NIOSH 7400 method, the issue regarding "relatively clean" environments" is addressed on page 4, number 4, note number 1 which states  "In relatively clean atmospheres, where targeted fiber concentrations are much less than 0.1 f/cc, use larger sample volumes (3000 to 10,000 liters) to achieve quantifiable loadings."  Even though the formula calculates that 3,850 liters of air should be collected, many people use note 1 to collect 3,000 liters of air for clearance.  Either way clearance samples should be collected using no less than 3,000 liters of air as the minimum allowed for the NIOSH 7400 method requirements and AHERA compliance. 

PCM image of fibers

The true problem is the NIOSH 7400 was never designed as a clearance tool, it was designed as a personal air sampling method.  NIOSH and the Occupational Health and Safety Administration (OSHA) still view the method in that manner officially.  The other problem with PCM is that all fibers meeting method criteria are counted, not just asbestos fibers.  The AHERA TEM method is the only procedure that was designed as a final clearance air sampling method. Only asbestos fibers/structures are counted in the analysis meeting method criteria for size, and those much smaller than can be determined by the PCM.

 

EPA's Silver Book

Realize this is not something out of the ordinary the EPA's publication "Measuring Airborne Asbestos Following An Abatement Action" (otherwise known as the Silver Book) written in November 1985 on page 2-6 recommends the sample volume for the PCM analysis should be a minimum of 3,000 liters of air (though at the time of this publication it was describing the NIOSH P&CAM 239 PCM methodology).  In addition, in March 2015 the EIA published a revision to the EPA's 1985 document "Guidance for Controlling Asbestos-Containing Materials in Buildings"(EPA 560/5-85-024, known as the Purple Book).  This nationally peer-reviewed document was re-titled "Managing Asbestos in Buildings: A Guide for Owners and Managers."  Chapter 5 (on page 88) says the minimum sampling volume of 3,000 liters of air for samples taken to meet the NIOSH 7400 method requirements for LOQ sampling.  Mr. Dana Brown did a video regarding the LOQ issue and why NIOSH 7400 method is not the best choice for clearance, you can see it below. 

This doesn't count that we have called for the AHERA TEM method to be utilized for asbestos-containing floor tiles and mastic removals based on our previous blog post "Asbestos Floor Tile Debate", published in the August 2017 issue of Healthy Indoors Magazine, which found that the NIOSH 7400 method is not able to analyze the type of fibers (Grade 7-Shorts and Floats that are known to be less than 5 microns) found in these materials because of the known small fiber sizes generated by floor tile work.  Whether AHERA-based work or asbestos abatement where re-occupancy will occur, the surest way to make sure an area is ready to be given back to the public to be free of asbestos as practicable by current methods, and the fastest method for clearance would be the AHERA TEM method.  

NYSDOL ICR56 Definition of an Asbestos Project

Of course, those of you who work in New York State or New York City realize these requirements only apply to public and private K-12 schools.  So they don't apply to other buildings, or do they?  First, let's take the NYSDOL ICR56 Subpart 56-4, page 35 is the air sampling requirements.  56-4.6 "Test Methods" on page 36 says "the same NIOSH approved methodology for project air sampling and for analysis of the air samples shall be used at all phases of an asbestos project that require area air sampling and analysis, with the possible exception of clearance air sampling."  This means that the NIOSH 7400 method must be followed for all phases except clearance (Phase IIC of the asbestos project) this allows you to use either the NIOSH 7400 method or the AHERA TEM method instead for clearance.  So this means you have to follow the NIOSH 7400 method's LOQ requirements for all phases (Phase I B and Phase II A, B, & C) of the asbestos project.  In addition, the NYSDOL ICR56 regulation for clearance is less than 0.01 f/cc so that changes the formula again.  Let's use 0.009 f/cc for the L instead and still use 16 liters per minute, well that means the sample has to run for 267 minutes, almost 4 hours, and 30 minutes (a total volume of air of 4,278 liters).

The consummate leader cultivates the moral law, and strictly adheres to method and discipline; thus it is in his power to control success. ~ Sun Tzu

So why does everyone sample 1,200 liters of air for all samples?  On April 8, 2011, the New York State Department of Health (NYSDOH) Wadsworth Center issued frequently asked questions (FAQs) regarding asbestos/fibers analysis that were developed through the collaboration of the NYSDOH Environmental Laboratory Approval Program (ELAP) and the Bureau of Occupational Health and the NYSDOL.  In this FAQ is FAQ#13: What is the minimum sampling volume to be collected for air sampling associated with (a) post-abatement (clearance) air monitoring and (b) post-abatement area monitoring for PCM analysis?  The answer that was given was:  Within the upcoming revision to NYS Industrial Code Rule 56, minimum air sample volume requirements 

are being added for both background and clearance PCM air samples. The minimum volume will be 1,200 liters for all background and clearance PCM air samples collected.  Hopefully, you all see the problem here...the code rule has not been revised to include this requirement, and even if it did change this is a minimum volume of air and does not comply with the NIOSH 7400 method requirement.

Buy our Asbestos Air Sampling Chart here.
Read about our Asbestos Air Sampling Charts here.

Next up is the NYCDEP Title 15.  NYCDEP Title 15 was just updated on May 28th, 2022.  See our blog post "New York City's Asbestos Regulation Revised, Again!" for more information on the changes.  However, these changes did not make any significant changes to what we are discussing.  Under Subpart D, 1-37 (b) "Area air sampling equipment for PCM shall be utilized in accordance with the sampling procedures specified within the NIOSH 7400 Method modified for area sampling."  Again, it means you must follow the LOQ requirements in the NIOSH 7400 method, even though NYCDEP Title 15 does give you minimum sample volumes.  For clearance by NIOSH 7400 method, it's 1800 liters and for the AHERA TEM method, it's 1250 liters.  Remember these are minimums.  In addition, NYCDEP Title 15 limits the flow rate to a maximum of 15 liters per minute.  This means to achieve the LOQ requirement it would take 256.7 minutes which is just short of 4 hours and 15 minutes (total volume of air of 3,850 liters).  The NYCDEP Title 15 minimum volume would not meet the LOQ requirements in the NIOSH 7400 method.  We hope this post has helped to resolve those pesky questions regarding clearance and convince you that probably the best air sampling method for clearance is the AHERA TEM method!