MA Edin 1896, MSc 1899, MB ChB 1901, MD 1908; DPH Camb 1902.
Mair was educated at the Universities of Edinburgh and Cambridge and held resident appointments in the public health service at Edinburgh and Leith. He did some postgraduate study in Hamburg before obtaining a pathological post at Belfast. In 1906, Mair was appointed demonstrator in pathology at the University of Manchester and pathologist to the Salford Royal Hospital and Manchester Children's Hospital. He was appointed lecturer in pathology in 1909.