Where I worked last this is how we applied the rule... If you were required to work in a place where a respirator was needed to protect you then you were required to have the seal test and "huff" testing, as well as the proper respirator provided to you. On the other hand if the conditions didn't warrant (read "below acceptable concentration / time limits") then it was the employee's option to wear one or not and the employeer didn't have to provide the equipment. Training was required in either case and if you weren't required to wear one you could still get the seal and huff test done.
Perhaps a little too loose after reading 1910.134.a.2 and 1910.134.c.2.
