Re: Air washing and Settling Times

[Guest guest]

,

The 24 hr settling time and then re-clean is a hang over from the

asbestos industry.

However, actual scientific verification that this actually works, and

to what effectiveness has never been measured.

Remember in Asbestos jobs, the last thing you do is to apply lock down

before air sampling. This makes sure that debris is not free to be

stirred up during aggressive clearance testing. My experience with asb

testing before and after lockdown, is that the 24 hour " settling time "

and reclean is more illusion than reality. It is the lock down that

actual entrains the fibers.

It also goes to the question of whether wet wiping actually picks up 5

- 10 micron fibers. I can tell you from clean medical device

testing- wet wiping is not effective. The parts have to be washed in

a 0.22 micron filtered bath for at least 30 minutes to have a

significant effect.

The research by Beard,et al on the asb. air testing method did show

that air movement does reentrain these small fibers (same size as mold

spores). Once they are reentrained they can be removed by the air

scrubbers. Hence, the recomendation for air washing.

However, air washing will make a structure cleaner than normal. This

also means that over time, depending upon the pressurization of the

building and the air filtering efficiency, it will return to a normal

dirtier states. EPA testing of homes where the HVAC ductwork was

cleaned-showed this takes as little as 6 weeks to occur.

My experience with the term 'air washing' is from clean room

validation. It is also used in HVAC industry (the oldest air washer I

have assessed was from 1890 in a food process plant)

http://www.naima.org/pages/benefits/ieq/issues.html

http://freepatentsonline.com/4410339.html

and the mold abatement industry.

http://www.aramsco.com/dopage.htm?i_itemno=72740 & _mc=mo

Air polishing is a more common term in dental hygiene for cleaning

teeth.

Bob

[Guest guest]

Not sure if I got the wrong message from

your reply but this is my take. Lock down or encapsulate should never be used

before or after air sampling. It is a temporary fix that will decay and release

fibres or spores at some future time.

Jeff Charlton

www.disasteradvice.co.uk

London

-----Original

Message-----

From: iequality

[mailto:iequality ] On Behalf

Of Bob s

Sent: 19 March 2006 15:12

To: iequality

Subject: Re: Air

washing and Settling Times

,

The 24 hr settling time and then re-clean is a

hang over from the

asbestos industry.

However, actual scientific verification that this

actually works, and

to what effectiveness has never been measured.

Remember in Asbestos jobs, the last thing you do

is to apply lock down

before air sampling. This makes sure that

debris is not free to be

stirred up during aggressive clearance

testing. My experience with asb

testing before and after lockdown, is that the 24

hour " settling time "

and reclean is more illusion than reality.

It is the lock down that

actual entrains the fibers.

It also goes to the question of whether wet wiping

actually picks up 5

- 10 micron fibers. I can tell

you from clean medical device

testing- wet wiping is not effective.

The parts have to be washed in

a 0.22 micron filtered bath for at least 30

minutes to have a

significant effect.

The research by Beard,et al on the asb. air

testing method did show

that air movement does reentrain these small

fibers (same size as mold

spores). Once they are reentrained they can be

removed by the air

scrubbers. Hence, the recomendation

for air washing.

However, air washing will make a structure

cleaner than normal. This

also means that over time, depending upon the

pressurization of the

building and the air filtering efficiency, it will

return to a normal

dirtier states. EPA testing of homes

where the HVAC ductwork was

cleaned-showed this takes as little as 6 weeks to

occur.

My experience with the term 'air washing' is from

clean room

validation. It is also used in HVAC industry

(the oldest air washer I

have assessed was from 1890 in a food process

plant)

http://www.naima.org/pages/benefits/ieq/issues.html

http://freepatentsonline.com/4410339.html

and the mold abatement industry.

http://www.aramsco.com/dopage.htm?i_itemno=72740 & _mc=mo

Air polishing is a more common term in dental

hygiene for cleaning

teeth.

Bob