Re: HEPA filter efficiency by size

[Guest guest]

Dear Carl:

The collection methods for particulate matter can be listed as:

Straining, Impingement, Interception, Diffusion, or Electrostatic (ACGIH,

Industrial Ventilation), or

Diffusion, Inertial, Interception, or Sieving (IAQ Handbook)

The evaluation criterion for HEPA filtration at 0.3 microns is chosen because

this is the most difficult size to be captured.

Thus particles smaller or larger will be captured with greater efficiency.

The comment that, " HEPA is only 99.97% effective down to .3 microns " is

therefore erroneous.

Sincerely,

W. Bearg, PE, CIH

IAQ Consultant and Building Scientist.

-------------- Original message ----------------------

> If there's anybody left out there that cares to respond, can you

> supply the chart showing HEPA retention of particles by size? I seem

> to remember previous discussions on this group about its

> effectiveness increasing below 0.3 microns due to forces other than

> simple mechanical straining.

>

> Carl Grimes

> Healthy Habitats LLC

>

> -----

> >

> > Bob,

> >

> > HEPA filters do not effectively filter small mold micro-

> > fragments.HEPA is only 99.97% effective down to .3 microns. In the

> > mold remediation environment where there can be millions or billions

> > of fragments that level of filtration will not work.

[Guest guest]

Carl,

A great website to understand HEPA filtration (and all other types of

filtration) is this page from NIOSH regarding building protection

from bioligical or chemical attack:

http://www.cdc.gov/niosh/docs/2003-136/2003-136c.html

Figure 4 addresses your question about particles smaller than ~0.3

microns being easier to remove (due to diffusion/Brownian motion).

Ian Cull, PE, CIEC

>

> Dear Carl:

>

> The collection methods for particulate matter can be listed as:

>

> Straining, Impingement, Interception, Diffusion, or Electrostatic

(ACGIH, Industrial Ventilation), or

>

> Diffusion, Inertial, Interception, or Sieving (IAQ Handbook)

>

> The evaluation criterion for HEPA filtration at 0.3 microns is

chosen because this is the most difficult size to be captured.

>

> Thus particles smaller or larger will be captured with greater

efficiency.

>

> The comment that, " HEPA is only 99.97% effective down to .3

microns " is therefore erroneous.

>

> Sincerely,

>

> W. Bearg, PE, CIH

>

> IAQ Consultant and Building Scientist.

>

>

>

>

> -------------- Original message ----------------------

>

> > If there's anybody left out there that cares to respond, can you

> > supply the chart showing HEPA retention of particles by size? I

seem

> > to remember previous discussions on this group about its

> > effectiveness increasing below 0.3 microns due to forces other

than

> > simple mechanical straining.

> >

> > Carl Grimes

> > Healthy Habitats LLC

> >

> > -----

> > >

> > > Bob,

> > >

> > > HEPA filters do not effectively filter small mold micro-

> > > fragments.HEPA is only 99.97% effective down to .3 microns. In

the

> > > mold remediation environment where there can be millions or

billions

> > > of fragments that level of filtration will not work.

>

[Guest guest]

Ian

That is a good reference on filters and filter efficiency but it continues a misinterpretation of the actual efficiency of the electrostatic filters on real house dust. Most of the electrostatic filters use plastic media that have a strong attraction for DOP, the liquid that is turned into droplets for the filter efficiency test. Many of these electrostatic filters that I see in the field have almost no fine house dust on them. It appears that they may even reject the types of dust found in houses. A flawed test procedure says that these filters work on DOP but I say they do not work on fine house dust.

Jim H. White SSC

Re: HEPA filter efficiency by size

Carl,A great website to understand HEPA filtration (and all other types of filtration) is this page from NIOSH regarding building protection from bioligical or chemical attack:http://www.cdc.gov/niosh/docs/2003-136/2003-136c.htmlFigure 4 addresses your question about particles smaller than ~0.3 microns being easier to remove (due to diffusion/Brownian motion).Ian Cull, PE, CIEC>> Dear Carl:> > The collection methods for particulate matter can be listed as:> > Straining, Impingement, Interception, Diffusion, or Electrostatic (ACGIH, Industrial Ventilation), or> > Diffusion, Inertial, Interception, or Sieving (IAQ Handbook)> > The evaluation criterion for HEPA filtration at 0.3 microns is chosen because this is the most difficult size to be captured.> > Thus particles smaller or larger will be captured with greater efficiency.> > The comment that, "HEPA is only 99.97% effective down to .3 microns" is therefore erroneous.> > Sincerely,> > W. Bearg, PE, CIH> > IAQ Consultant and Building Scientist.> > > > > -------------- Original message ----------------------> > > If there's anybody left out there that cares to respond, can you > > supply the chart showing HEPA retention of particles by size? I seem > > to remember previous discussions on this group about its > > effectiveness increasing below 0.3 microns due to forces other than > > simple mechanical straining.> > > > Carl Grimes> > Healthy Habitats LLC> > > > -----> > > > > > Bob,> > > > > > HEPA filters do not effectively filter small mold micro-> > > fragments.HEPA is only 99.97% effective down to .3 microns. In the > > > mold remediation environment where there can be millions or billions > > > of fragments that level of filtration will not work.>

[Guest guest]

Ian, That is a very good article. So smaller particles than .3 micron are collected better with a HEPA filter (appears to be a Merv 17 filter.) In any event, micro-particles in the .3 micron range are only collected to 99.97%. These size particles are hard to trap compared to larger spore size particles (or smaller particles.) 1 sq inch of mold growth can have 100M spore equivalents when analyzed by PCR. Mold fragments are released in much higher numbers than are spores (I have articles on this I can send you.) Therefore if you multiply 100M+ x .9997 you get many fragments getting thru the filters. Relying on filtration for mold remediation is not a good idea. In addition, recent work has shown that fragments can be more detrimental to health than the larger spores. (I have articles on this as

well.) According to an article by well known researcher Gorny: The hitherto obtained results using the aerosolisation chamber show that a significantly higher number of microbial propagules with diameters smaller than those of the spores is released from microbiologically contaminated surfaces [59, 60]. ... the number of aerosolised fragments can be several hundred times higher than the number of released intact spores from the same surface area. The presence of the submicrometer propagules released in such a way can be documented by scanning electron microscope (SEM) analysis. Bottom line ... smash and tear inside a

containment under the assumption that an air scrubber will remove mold spores along with mold micro-fragments is challenged by the latest research. The EPA recommendation that you build a containment around the problem material and put a fan in an outside window sucking the spores and fragments outside is a much better approach based on the latest research. Now there are more sophisticated methods for exhausting outside using axial fans and ducting than a window fan ... but the basic concept of removing the problem by blowing it out the window is the best approach. Because we do not contaminate homes with micro-fragments while most others do, is perhaps why our clients get better after we fix their homes where according to Dr. Shoemaker mold remediations fail and people stay sick or get sicker as a result of mold remediation work. Rosen,

Ph.D. www.Mold-Books.comIan Cull wrote: Carl,A great website to understand HEPA filtration (and all other types of filtration) is this page from NIOSH regarding building protection from bioligical or chemical attack:http://www.cdc.gov/niosh/docs/2003-136/2003-136c.htmlFigure 4 addresses your question about particles smaller

than ~0.3 microns being easier to remove (due to diffusion/Brownian motion).Ian Cull, PE, CIEC>> Dear Carl:> > The collection methods for particulate matter can be listed as:> > Straining, Impingement, Interception, Diffusion, or Electrostatic (ACGIH, Industrial Ventilation), or> > Diffusion, Inertial, Interception, or Sieving (IAQ Handbook)> > The evaluation criterion for HEPA filtration at 0.3 microns is chosen because this is the most difficult size to be captured.> > Thus particles smaller or larger will be captured with greater efficiency.> > The comment that, "HEPA is only 99.97% effective down to .3 microns" is therefore erroneous.> > Sincerely,> > W. Bearg, PE, CIH> > IAQ

Consultant and Building Scientist.> > > > > -------------- Original message ----------------------> > > If there's anybody left out there that cares to respond, can you > > supply the chart showing HEPA retention of particles by size? I seem > > to remember previous discussions on this group about its > > effectiveness increasing below 0.3 microns due to forces other than > > simple mechanical straining.> > > > Carl Grimes> > Healthy Habitats LLC> > > > -----> > > > > > Bob,> > > > > > HEPA filters do not effectively filter small mold micro-> > > fragments.HEPA is only 99.97% effective down to .3 microns. In the > > > mold remediation environment where there can be millions or billions

> > > of fragments that level of filtration will not work.>

Access over 1 million songs - Yahoo! Music Unlimited.

[Guest guest]

" I propose a Gathering of Eagles ready and willing to take Flight. The

Bottom Feeders can either grow wings and soar with us or grovel in the

mud amongst themselves. "

GOOD one ! I had to write that one down!

I believe this is applicable in this situation and discussion.

My saying was as wuch:

" This has collapsed into a monkey poo fight over minutia. "

[Guest guest]

,

I have understood that a HEPA filter (or

any filter for that matter) works better the more it captures (to a point). How

about a HEPA filter filtering out the body fragments below .3 microns due to

loading?

Bob/Ma.

From: iequality [mailto:iequality ] On Behalf Of gary rosen

Sent: Wednesday, February 28, 2007

5:43 PM

To: iequality

Subject: Re: Re: HEPA

filter efficiency by size

Ian,

That is a very good article. So smaller particles than .3 micron

are collected better with a HEPA filter (appears to be a Merv 17 filter.)

In any event, micro-particles in the .3 micron range are only collected

to 99.97%. These size particles are hard to trap compared to larger spore size

particles (or smaller particles.)

1 sq inch of mold growth can have 100M spore equivalents when analyzed

by PCR. Mold fragments are released in much higher numbers than are

spores (I have articles on this I can send you.)

Therefore if you multiply 100M+ x .9997 you get many fragments getting

thru the filters. Relying on filtration for mold remediation is not

a good idea.

In addition, recent work has shown that fragments can be more

detrimental to health than the larger spores. (I have articles on this as

well.)

According to an article by well known researcher Gorny:

The hitherto obtained results using the aerosolisation

chamber show that a significantly higher number of

microbial propagules with diameters smaller than those of

the spores is released from microbiologically

contaminated surfaces [59, 60]. ... the number of aerosolised

fragments can be several hundred times higher than the

number of released intact spores from the same surface

area. The presence of the submicrometer propagules

released in such a way can be documented by scanning

electron microscope (SEM) analysis.

Bottom line ... smash and tear inside a containment under the

assumption that an air scrubber will remove mold spores along with mold

micro-fragments is challenged by the latest research.

The EPA recommendation that you build a containment around the problem

material and put a fan in an outside window sucking the spores and fragments

outside is a much better approach based on the latest research. Now there

are more sophisticated methods for exhausting outside using axial fans and

ducting than a window fan ... but the basic concept of removing the

problem by blowing it out the window is the best approach.

Because we do not contaminate homes with micro-fragments while most

others do, is perhaps why our clients get better after we fix their homes where

according to Dr. Shoemaker mold remediations fail and people stay sick or get

sicker as a result of mold remediation work.

Rosen, Ph.D.

www.Mold-Books.com

Ian Cull

<icullchelseatraining> wrote:

Carl,

A great website to understand HEPA filtration (and all other types of

filtration) is this page from NIOSH regarding building protection

from bioligical or chemical attack:

http://www.cdc.gov/niosh/docs/2003-136/2003-136c.html

Figure 4 addresses your question about particles smaller than ~0.3

microns being easier to remove (due to diffusion/Brownian motion).

Ian Cull, PE, CIEC

>

> Dear Carl:

>

> The collection methods for particulate matter can be listed as:

>

> Straining, Impingement, Interception, Diffusion, or Electrostatic

(ACGIH, Industrial Ventilation), or

>

> Diffusion, Inertial, Interception, or Sieving (IAQ Handbook)

>

> The evaluation criterion for HEPA filtration at 0.3 microns is

chosen because this is the most difficult size to be captured.

>

> Thus particles smaller or larger will be captured with greater

efficiency.

>

> The comment that, " HEPA is only 99.97% effective down to .3

microns " is therefore erroneous.

>

> Sincerely,

>

> W. Bearg, PE, CIH

>

> IAQ Consultant and Building Scientist.

>

>

>

>

> -------------- Original message ----------------------

>

> > If there's anybody left out there that cares to respond, can you

> > supply the chart showing HEPA retention of particles by size? I

seem

> > to remember previous discussions on this group about its

> > effectiveness increasing below 0.3 microns due to forces other

than

> > simple mechanical straining.

> >

> > Carl Grimes

> > Healthy Habitats LLC

> >

> > -----

> > >

> > > Bob,

> > >

> > > HEPA filters do not effectively filter small mold micro-

> > > fragments.HEPA is only 99.97% effective down to .3 microns. In

the

> > > mold remediation environment where there can be millions or

billions

> > > of fragments that level of filtration will not work.

>

Access over 1 million songs - Yahoo!

Music Unlimited.

[Guest guest]

Ok Group,

Based on ’s article how does that affect the

EPA’s 10Sf threshold? If body fragments being released are a player in

the remediation process than should that also become a factor in determining

containment?

Bob/Ma.

From: iequality [mailto:iequality ] On Behalf Of gary rosen

Sent: Wednesday, February 28, 2007

5:43 PM

To: iequality

Subject: Re: Re: HEPA

filter efficiency by size

Ian,

That is a very good article. So smaller particles than .3 micron

are collected better with a HEPA filter (appears to be a Merv 17 filter.)

In any event, micro-particles in the .3 micron range are only collected

to 99.97%. These size particles are hard to trap compared to larger spore size

particles (or smaller particles.)

1 sq inch of mold growth can have 100M spore equivalents when analyzed

by PCR. Mold fragments are released in much higher numbers than are

spores (I have articles on this I can send you.)

Therefore if you multiply 100M+ x .9997 you get many fragments getting

thru the filters. Relying on filtration for mold remediation is not

a good idea.

In addition, recent work has shown that fragments can be more

detrimental to health than the larger spores. (I have articles on this as

well.)

According to an article by well known researcher Gorny:

The hitherto obtained results using the aerosolisation

chamber show that a significantly higher number of

microbial propagules with diameters smaller than those of

the spores is released from microbiologically

contaminated surfaces [59, 60]. ... the number of aerosolised

fragments can be several hundred times higher than the

number of released intact spores from the same surface

area. The presence of the submicrometer propagules

released in such a way can be documented by scanning

electron microscope (SEM) analysis.

Bottom line ... smash and tear inside a containment under the

assumption that an air scrubber will remove mold spores along with mold

micro-fragments is challenged by the latest research.

The EPA recommendation that you build a containment around the problem

material and put a fan in an outside window sucking the spores and fragments

outside is a much better approach based on the latest research. Now there

are more sophisticated methods for exhausting outside using axial fans and

ducting than a window fan ... but the basic concept of removing the

problem by blowing it out the window is the best approach.

Because we do not contaminate homes with micro-fragments while most

others do, is perhaps why our clients get better after we fix their homes where

according to Dr. Shoemaker mold remediations fail and people stay sick or get

sicker as a result of mold remediation work.

Rosen, Ph.D.

www.Mold-Books.com

Ian Cull

<icullchelseatraining> wrote:

Carl,

A great website to understand HEPA filtration (and all other types of

filtration) is this page from NIOSH regarding building protection

from bioligical or chemical attack:

http://www.cdc.gov/niosh/docs/2003-136/2003-136c.html

Figure 4 addresses your question about particles smaller than ~0.3

microns being easier to remove (due to diffusion/Brownian motion).

Ian Cull, PE, CIEC

>

> Dear Carl:

>

> The collection methods for particulate matter can be listed as:

>

> Straining, Impingement, Interception, Diffusion, or Electrostatic

(ACGIH, Industrial Ventilation), or

>

> Diffusion, Inertial, Interception, or Sieving (IAQ Handbook)

>

> The evaluation criterion for HEPA filtration at 0.3 microns is

chosen because this is the most difficult size to be captured.

>

> Thus particles smaller or larger will be captured with greater

efficiency.

>

> The comment that, " HEPA is only 99.97% effective down to .3

microns " is therefore erroneous.

>

> Sincerely,

>

> W. Bearg, PE, CIH

>

> IAQ Consultant and Building Scientist.

>

>

>

>

> -------------- Original message ----------------------

>

> > If there's anybody left out there that cares to respond, can you

> > supply the chart showing HEPA retention of particles by size? I

seem

> > to remember previous discussions on this group about its

> > effectiveness increasing below 0.3 microns due to forces other

than

> > simple mechanical straining.

> >

> > Carl Grimes

> > Healthy Habitats LLC

> >

> > -----

> > >

> > > Bob,

> > >

> > > HEPA filters do not effectively filter small mold micro-

> > > fragments.HEPA is only 99.97% effective down to .3 microns. In

the

> > > mold remediation environment where there can be millions or

billions

> > > of fragments that level of filtration will not work.

>

Access over 1 million songs - Yahoo!

Music Unlimited.

[Guest guest]

Good

Afternoon Group,

For anyone wishing to know more about the

HEPA filter…

The National

Air Filtration Association (NAFA) has a publication

(Air Media) that is sent out to

its members on a quarterly basis.

I believe there was an article on the “History

of the HEPA Filter” that was published about two issues ago Fall 2006.

If you contact the National Air Filtration Association (NAFA) Web: www.nafahq.org Tel.

Fax: or email: nafa@...

Mention my name (Steve ) and the request

the Fall 2006 issue of Air Media I

will offer to send a complimentary copy to any iequality group member

that would like to have this article for

reference purposes.

Respectfully submitted,

W. , CAFS, NCT

President, NAFA 2006-2007

Re: HEPA

filter efficiency by size

Dear Carl:

The collection methods for particulate matter can be listed as:

Straining, Impingement, Interception, Diffusion, or Electrostatic (ACGIH,

Industrial Ventilation), or

Diffusion, Inertial, Interception, or Sieving (IAQ Handbook)

The evaluation criterion for HEPA filtration at 0.3 microns is chosen because

this is the most difficult size to be captured.

Thus particles smaller or larger will be captured with greater efficiency.

The comment that, " HEPA is only 99.97% effective down to .3 microns "

is therefore erroneous.

Sincerely,

W. Bearg, PE, CIH

IAQ Consultant and Building Scientist.

-------------- Original message ----------------------

From: " Carl E. Grimes " <grimeshabitats>

> If there's anybody left out there that cares to respond, can you

> supply the chart showing HEPA retention of particles by size? I seem

> to remember previous discussions on this group about its

> effectiveness increasing below 0.3 microns due to forces other than

> simple mechanical straining.

>

> Carl Grimes

> Healthy Habitats LLC

>

> -----

> >

> > Bob,

> >

> > HEPA filters do not effectively filter small mold micro-

> > fragments.HEPA is only 99.97% effective down to .3 microns. In the

> > mold remediation environment where there can be millions or billions

> > of fragments that level of filtration will not work.