I use a very bright red LED - probably 1 W and it will fog my ISO 3 homemade emulsions (which are not pan) if left withing 1 inch for 30 seconds. About the same for paper. I've never had any issue with fog at all, for any length of time (including the 2 or 3 hours it takes to make a liquid emulsion) at distances greater than a foot. For B&W papers and lower speed ortho films, there is very little risk of fog with Red LED's in my experience. You have to actually try to fog the paper/ortho film. I use the same light with Arista Ortho film quite often, and have suffered no ill effects.