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RE: Germ-Free Humidifiers-Ozone Production
Germicidal lamps are low pressure mercury discharge lamps. They are
essentially fluorescent lamps without phosphor and in bulbs that transmit
the 253.7 nm mercury line. Most are "ozone-free" in that the bulb
transmittance cuts off above the ozone producing 184.9 nm mercury line.
Such bulbs are made using UV transmitting glass or certain types of quartz.
Some special germicidal lamps have a bulb made with a type of quartz that
will transmit below 200 nm, and these lamps are identified as ozone
generating lamps.
Robert E. Levin, Ph.D.
Corporate Scientist
OSRAM SYLVANIA
71 Cherry Hill Drive
Beverly, MA 01915
phone: (978) 750-1594
fax: (978) 750-1794
e-mail: robert.levin@sylvania.com
> -----Original Message-----
> From: Richard C. Mannix [SMTP:rcmannix@uci.edu]
> Sent: Thursday, November 18, 1999 3:02 PM
> To: Multiple recipients of list
> Subject: Germ-Free Humidifiers-Ozone Production
>
> <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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