(a) impairment requiring confinement to a wheel chair; or
(b) impairment causing difficulty or insecurity in walking or climbing stairs or requiring the use of braces, crutches or other artificial supports; or impairment caused by amputation, arthritis, spastic condition or pulmonary, cardiac or other ills rendering the individual semi-ambulatory; or
(c) total or partial impairment of hearing or sight causing insecurity or likelihood of exposure to danger in public places; or
(d) impairment due to conditions of aging and incoordination. 6. "Reconstruction, rehabilitation, alteration or improvement" shall mean only that work which results in a substantial change in the structure or facilities of a public building and shall not include minor repairs necessary for ordinary maintenance.