Re: Infrared

["Randy Ross" <RNROSS@BCSC02.GOV.BC.CA>]

To: RADSAFE --INTERNET RADSAFE@ROMULUS.EH


The researcher should know which IR band that his "light" source will be
emitting. That is what wavelengths are coming out of the lamp. Then to protect
the cornea from thermal injury and to avoid possible delayed effects upon the
lens of the eye (cataractogenesis) infrared radiation from 770nm to 3
micrometers for exposures for long periods should be kept less than 10 mW/cm2
(that's a time average intensity.)

 To protect the retina from near IR or IR-A (770nm -1400nm), the radiance
should be limited to #(%*^(*@^$#?? or a complex formula and table of values
found in the American Conference of Governmental and Industrial Hygienists
(ACGIH) TLV booklet 1995/6 or older years.

 Having said all that I think that the researcher should determine whether its
safe from a worst case point of view ie sleeping with ones eyes open and using
the above information. Then once he has done that (first he does that) then
once he knows that is safe he can reassure himself by saying things like
"campers sleep around bonfires that are 50 - 100 mW/cm2 and don't seem to go
blind" & some people have IR heating in their ceilings and they can feel
  the heat but it is not harmful except that the tops of their heads and any
other horizontal surfaces are hot and their body and the room air temperature
is cold.

It's not likely that the lamp or lamps being used for illuminating
the person is going to make the person's skin feel hot. Ordinary light bulbs
produces alot of IR but don't make you skin feel warm unless you are close to
the bulb. The IR source does not need to be powerful if the researcher buys a
sensitive IR camera.

Radiation Protection, Ministry of Health, British Columbia
The opinions and material above are solely those of the author.
This is a disclaimer for postings to bulletin boards, newsgroups
etc., on the internet.  Randy Ross, rnross@bcsc02.gov.bc.ca