Germ-Free Humidifiers-Ozone Production

["Richard C. Mannix" <rcmannix@uci.edu>]

> 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. 

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 ************************************************************************ The RADSAFE Frequently Asked Questions list, archives and subscription information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html