Re: Radon and Respiratory protection

[BERNARD L COHEN <blc+@PITT.EDU>]

On Wed, 3 Sep 2003, Jay Beckel wrote:



> Do HEPA cartridges provide ANY protection at all in a radon atmosphere?  Are

> there any studies out there that would back up any theories of radon

> attachment to particles and therefore being caught up in the HEPA?



	--This is a complicated question. The danger from radon comes from

radon progeny which normally attach to fine dust particles. Thus, removing

dust from the air inhaled reduces inhalation of these, reducing the

"working level". But removing the dust from the air causes an increased

fraction of the progeny to remain unattached to dust particles, and

unattached radon progeny are more likely to attach to the bronchial

surfaces which makes them more dangerous. These two effects approximately

compensate, so little is gained by filtering dust out of the room air.

Filtering dust out of air as it is inhaled would be quite useful in

reducing exposure, but this is not convenient in most cases.

	There is no need for HEPA filters, which are to remove over 99% of

the dust. Removing 80% or 90% would do nearly as much good.

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