From the West System website:

"Provide ample ventilation when working with epoxy in confined spaces, such as boat interiors. When you can't adequately ventilate your workspace, wear an approved respirator with an organic vapor cartridge."

Like System 3, they do not say that working with epoxy in a space as large as a garage requires a respirator.

You yourself said that you should verify information you glean off the internet. Well, we haven't found good verification of your fears regarding epoxy sensitization via inhilation -- we've now got 2 major manufacturers who say that wearing respirators is recommended only for very confined spaces.

: The following was added to my web site. It is now my current view of the
: proper use of System 3 epoxy. I will not object to it again.

: A different view was given by System 3, an epoxy formulator. On the second
: point only: You should have "adequate ventilation".

: A closed garage is sufficient.

: A respirator is not needed.