A physicаl therаpy оrthоpedic clinic hаs an оffice on the second floor of a building that has no elevator. An employee who has bilateral limb amputations and is considered to have a disability leaves his wheelchair downstairs and uses crutches to climb the stairs to the second floor of the clinic. The clinic is employing one PT, three PTAs, and two clerks. Why doesn’t this employer have to install an elevator in the building?