RE: Germ-Free Humidifiers-Ozone Production

["Neil, David M" <neildm@id.doe.gov>]

I'm not totally sure you should worry about the ozone production, if there
is any.   It seems that there is a great deal of argument about how
healthful/dangerous low concentrations are.   On the one side are the
numerous proponents who point to the oxidation of impurities, dust and
pollen precipitation, and germicidal effects, and on the other, the EPA, et
al , saying that one whiff and you're stiff (exaggeration!).

Stipulating that "n" is far too small for validity in this study, I have had
21 months observation of an infant who has been exposed '24/7' to an air
purifier of this type, with no observable negative effects (99th percentile
for growth, active, precocious, beautiful).  See
http://home.rmci.net/maclir/angel01.htm for some older pictures of her.
Dave Neil		neildm@id.doe.gov

Make something "idiot proof" and someone will make a better idiot

On Thursday, November 18, 1999 1:03 PM, Richard C. Mannix
[SMTP:rcmannix@uci.edu] wrote:
> <excerpt>Here's a question for you non-ionizing radiation types.
> 
> 
> The mother of a newborn called me recently and said that their
> pediatrician had recommended that a humidifier be purchased and placed in
> the area of the baby's crib. The mother found something called a
> "Germ-free Humidifier" in a catalog that claims to keep the water being
> vaporized pure via UV irradiation. She asked if I would recommend such a
> device. She really liked the "germ-free" feature, but was afraid of the
> UV radiation (it turns out that the radiation is totally
> enclosed/shielded).
> 
> 
> My first concern was that ozone may also be produced by the UV radiation,
> and that the baby sure doesn't need that gas as a significant component
> in the air she breathes. I contacted the company that makes the machine
> and asked them whether the device generates a significant amount of
> ozone. The reply is below:
> 
> ----------------------
> 
>  
> 
> Dear Mr. Mannix:
> 
>     In answer to your concern expressed in your Email, the Germicidal UV
> Bulb in the Slant/Fin Humidifiers operates at a wavelength of 253.7 nm.
> This is out of the range of Ozone producing wavelengths, which are
> between 180 and 220 nm. 
> 
>  --------------------- 
> 
>   
> 
> This seems a bit strange to me. If memory serves me, the wavelength
> mentioned (254 nm)  is the mercury vapor line and will produce ozone from
> the irradiation of air. But I'm not absolutely certain of this. 
> 
> </excerpt>
> 
> Anybody know the answer to this?
> 
> 
> Also, does anybody know a reference for the odor threshold of ozone? I
> believe that it is about 0.05 ppm, but I need a citable reference.
> 
> 
> Thanks.
> 
> 
> 
> 
> 
> Rick Mannix
> 
> Health Physicist
> 
> Laser Safety Officer
> 
> Univ. of California
> 
> 300 University Tower
> 
> Irvine, CA 92697-2725
> 
> 
> 949-824-6098
> 
> rcmannix@uci.edu
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