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karan

Looking for Info on Micron Size of Microcryastalline Silica

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karan    0

Hi everyone-

I am looking for SPECIFIC information that can be confirmed in official documentation or writings regarding the size of microcrystalline silica dust particles. My school is looking at whether or not my filtration unit in my classroom will effectively filter microcrystalline silica. (I am thinking it does not currently...)

 

I have been asked to provide the size of the micron needed for effective filtration. I gave an estimate to the guy who asked me that it needed to filter particles that were less than a micron. I told him that I thought the only filters effective enough to do that were HEPA filters. It appears mine are not. That is a great concern for me, as I've been teaching in this room with a filtration system that may have been spewing microcrystalline silica back into the air that I breathe on a daily basis for 9 years!

 

So, my question is: Can anyone give me the size of filtration needed, and back it up with official documentation, link, book, etc, that I can site?

 

Any help would be GREATLY appreciated! Thanks in advance!

 

Karan Witham-Walsh

HS Ceramics Teacher,

Mason, Ohio

 

Ohio

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teardrop    2

Some stuff I dug up in a search on silicosis and silica dust/flour

 

 

 

http://en.wikipedia.org/wiki/Silicosis

 

 

 

FYI.....the "um" rating in the article below is what we call microns in the US.

 

From page 8 of this publication http://www.who.int/ipcs/publications/cicad/en/cicad24.pdf

 

7. COMPARATIVE KINETICS AND

 

METABOLISM IN LABORATORY ANIMALS

 

AND HUMANS

 

Quartz enters the body as a particle. Usually the

 

particle is inhaled, and it may be deposited in the lung.

 

Solid particulates such as quartz are often described by

 

size range. For example, “coarse†particles are usually

 

described as particles with a diameter more than 2 μm;

 

“fine†particles are those with diameters in the range of

 

0.1–2.0 μm; and “ultrafine†particles are described as

 

particles with a diameter less than 0.1 μm. While particle

 

size is often described as geometric mean diameter in

 

inhalation studies, the aerodynamic characteristics of the

 

particle are important, too. In humans, inhalation of

 

“respirable†particles involves exposure to the particles

 

in a mineral dust that are able to penetrate into the

 

alveolar spaces of the lungs. It is generally considered

 

that respirable particles have an aerodynamic diameter of

 

<3–4 μm, while most particles larger than 5 μm may be

 

deposited in the tracheobronchial airways and thus not

 

reach the alveolar region (IARC, 1997). Particles

 

deposited in the respiratory bronchioles and proximal

 

alveoli are cleared more slowly and are more likely to

 

injure the lung.

 

 

The first page of this publication gives the acceptable OSHA standard (PEL) for the workplace

 

http://www.cdc.gov/niosh/docs/81-123/pdfs/0553.pdf

 

I hope that helps in some way.

 

be safe, be well

 

teardrop

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Mark C.    1,807

Heres a post by John

About my filter unitIts on the( working clean thread)I did get some Hepa filters to retro fit it .Read that thread

http://ceramicartsda...-working-clean/

WARNING!!!!!!!!

 

That particular filter unit does not have a filtration system that is suitable for microcrystaline respirable silica dusts. The only one that is approved for that kind of use is a HEPA type filter (or a P-100 type). That type of filter goes into the SUB micron range... not the micron plus level, as is stated on the Delta product literature for that unit. Government standards for HEPA filters for silica dusts say it must remove 99.97% of particles greater than 0.3 micrometer from the air. The fliter that comes with that unit appears to stop nothing below 1 micron. It is the sub micron particles that are of REAL concern.

 

Please remember that even HEPA filtered active air filters are the last line of defense on silica dust and need to be sized correctly as to the total room air volume and the level of contaminant that is present. Plus the location that the filters are installed is important too.

 

The first line of defense is preventuion of the material getting into the air in the first place, second is local pickup ventilation at the dust/fume/gas generation source (if that can be done), third is general dlitution ventilation of the entire space. It is only after all of that stuff is already addressed that active air filters aere suggested to pick up the final little "slack" in the rest of the system. This is pretty standard industrial hygiene practice.

 

If you happen to be IN the studio in the 24 to 36 hours that the sub-micron particles can remain in still air, you also have two OTHER active air filters working..... your lungs. If the filter unit is located on the ceiling, then the dust generated by you working probably is in your breathing zone before it ever reaches the air filter up on the roof.

 

best,

 

.............john

John Baymore

President; Potters Council

 

http://www.JohnBaymore.c

 

 

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karan    0

Heres a post by John

About my filter unitIts on the( working clean thread)I did get some Hepa filters to retro fit it .Read that thread

http://ceramicartsda...-working-clean/

WARNING!!!!!!!!

 

That particular filter unit does not have a filtration system that is suitable for microcrystaline respirable silica dusts. The only one that is approved for that kind of use is a HEPA type filter (or a P-100 type). That type of filter goes into the SUB micron range... not the micron plus level, as is stated on the Delta product literature for that unit. Government standards for HEPA filters for silica dusts say it must remove 99.97% of particles greater than 0.3 micrometer from the air. The fliter that comes with that unit appears to stop nothing below 1 micron. It is the sub micron particles that are of REAL concern.

 

Please remember that even HEPA filtered active air filters are the last line of defense on silica dust and need to be sized correctly as to the total room air volume and the level of contaminant that is present. Plus the location that the filters are installed is important too.

 

The first line of defense is preventuion of the material getting into the air in the first place, second is local pickup ventilation at the dust/fume/gas generation source (if that can be done), third is general dlitution ventilation of the entire space. It is only after all of that stuff is already addressed that active air filters aere suggested to pick up the final little "slack" in the rest of the system. This is pretty standard industrial hygiene practice.

 

If you happen to be IN the studio in the 24 to 36 hours that the sub-micron particles can remain in still air, you also have two OTHER active air filters working..... your lungs. If the filter unit is located on the ceiling, then the dust generated by you working probably is in your breathing zone before it ever reaches the air filter up on the roof.

 

best,

 

.............john

John Baymore

President; Potters Council

 

http://www.JohnBaymore.c

 

 

 

 

Thanks, Mark!

I did read (and copy) that post of John's previously... however, I need specific citable references for my administration re: particulate size...Thanks! Glad you got your new filters! :-) Karan

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JBaymore    1,432

Karan,

 

Go to US OSHA's website for all the info your school should need about this issue. The fact that THEY do not already know to look there is a bit scary! Your adminsitration should already KNOW about this stuff and be complying... as should your department head of Buildings and Grounds.

 

Get the MSDSs for all the materials that you use in the studio also. Some of the information thay will need is on there also.

 

Asking YOU tor provide the occupational health and safety documentation is like asking you to provide the instructions for the surgeon that is about to take out your appendix!

 

As an employee of the school ... you are covered by OSHA regs. And the school must comply with those regs.

 

Microcrystalline silica issues are well known and documented.

 

And YES... you MUST have HEPA filtered air cleaners. And remember also that THEY are not to be the prime dust control protocol.

 

Hope this helps.

 

best,

 

.......................john

 

PS: I see this kind of crazy stuff too often when I do consulting work. Sorry they are making you do their work.

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