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#1 09-29-2007 12:04:43
- JCamplin
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- Registered: 08-10-2007
- Posts: 3
0.8 vs. 0.45 pore size filter media for TEM air sampling
I have noticed that many TEM air sampling studies have opted for using 0.8 filter pore size over the 0.45 pore size during sampling events. Would a larger pore size collect less fibers?
Some air sampling methods require 0.45 pore sizes while other methods allow for either 0.45 or 0.8 pore sizes. Is anyone aware of an efficiency difference or loading variation if the larger pore size is used? Would I expect to collect the same size asbestos fibers and the same amount of fibers with either size filter media? What impact would this have on the analytical results?
I would be interested in anyones opinion and/or knowledge of any studies/findings on this topic.
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#2 11-27-2007 12:36:34
- Mike Beard
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- Registered: 11-27-2007
- Posts: 1
Re: 0.8 vs. 0.45 pore size filter media for TEM air sampling
Jeff,
RTI did a study for EPA which was presented at the Charlotte Conference. In short, if you are only interested in fibers longer than 5 micrometers in length, either filter may be used. If you are interested in fibers shorter than 5, you should use 0.45 MCEs.
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#3 11-30-2007 08:42:32
- JP Brake
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- Registered: 07-30-2007
- Posts: 9
Re: 0.8 vs. 0.45 pore size filter media for TEM air sampling
Are there any health studies that evaluate asbestos fibers smaller than 5 um to asbestos -related health issues?
It's my understanding that initial studies were done before TEM/SEM were widely available and economically feasible - Hence, only 5 um and longer fibers were considered.
However, I've also seen data reported that the majority of fibers inhaled are much smaller than 5 um.
It seems there is a HUGE unknown here.
Are small fibers responsible for asbestos health issues or are only the longer fibers the bad guys?
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#4 01-02-2008 12:57:06
- Tom L.
- New member
- From: Mareitta, GA (Atlanta metro)
- Registered: 10-29-2007
- Posts: 1
Re: 0.8 vs. 0.45 pore size filter media for TEM air sampling
Perry
There have been many....for years...and the data is a messy debate in the eyes of some...and it gets cloudier becasue of the defendant's lawyers. The best primer on this will be your attendance at the keynote session at the conference in March in Albuquerque. Dr. Ron Dodson will be speaking on this very issue...he's one of the best minds in this industry on this issue and he has a LOT to say about fibers below the OSHA-specified fiber length of > 5 micrometers.
One recent source you can look up on this is Dr. Suzuki's paper on mesothelioma tissues...>90% of the asbestos fibers he found in meso tissues were below 5 micrometers, and almost all were chrysotile.
Tom L.
Last edited by Tom L. (01-02-2008 13:19:01)
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#5 09-29-2008 09:53:21
- JCamplin
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- Registered: 08-10-2007
- Posts: 3
Re: 0.8 vs. 0.45 pore size filter media for TEM air sampling
I have made a challenge to the recently published document "Sampling and Analysis of Asbestos Fibers on Filter Media to Support Exposure Assessments: Bench-Scale Testing" on pore size efficiency by the EPA. You can read up on the current status of the challenge at:
http://www.epa.gov/QUALITY/informationg … list.html.
Scroll down to RFC 08002 where you can look at my original complaint and recent revision.
Jeff Camplin
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#6 06-08-2009 06:18:55
- troyjohns
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- Registered: 05-30-2009
- Posts: 6
Re: 0.8 vs. 0.45 pore size filter media for TEM air sampling
Given the risk of often fatal diseases associated with asbestos exposure, a lot of laws have been passed in recent times to ensure the safety of the public. A significant piece of legislation to pass was Regulation 4, which is to do with asbestos surveys and the duty to manage asbestos.
The regulation's main application is to do with non-domestic properties and places responsibility on the "duty holder" to ensure they identify, manage and properly monitor asbestos in the building.
The term "duty holder" is outlined in the Approved Code of Practice 127. The definition includes the self-employed and employers if it is their responsibility to maintain a non-domestic property. To simplify, the code states that if you control the maintenance of a non-domestic building then you're the "duty holder".
Asbestos surveys come into play here. The "duty holder" is required by the code to do inspections in relation to asbestos. Most hire a specialist to perform this task. Any information coming out of the inspections needs to be maintained for life and recorded on a register. If you have contractors visiting your property you need to make this register available on request.
A guidance note called MDHS 100 Surveying Sampling & Assessment of Asbestos Containing Materials outlines the surveys that can be done. These include:-
A Location & Assessment Survey
This survey aims to find suspect asbestos products on the premises and assess them. It is a presumptive survey.
Standard sampling
This survey is for assessing and identifying the suspect asbestos products. That is, it builds on the location & assessment survey by taking samples of suspect products and analysing them. If it's a small job this test can be performed on site, but in a lot of cases samples need to be sent away.
Full access and identification survey
This survey is conducted before a refurbishment or demolition occurs. Its purpose is to locate and study all the products that contain asbestos in a property. To work out how much of a building contains asbestos material a full program of sampling is undertaken. Usually this survey takes place to work out whether a building needs to be demolished or whether a refurbishment will suffice.
Author: Ply Plema
Last edited by troyjohns (06-24-2009 21:56:12)
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