OCGA 48-5-41 (a) (4) provides that "all institutions of purely public charity" are "exempt from all ad valorem property taxes in this state." In York Rite &c. v. Bd. of Equalization, 261 Ga. 558 (408 SE2d 699) (1991), the Georgia Supreme Court clarified the factors that must be present for an organization to qualify as an institution of "purely public charity" under this Code section. "First, the owner must be an institution devoted entirely to charitable pursuits; second, the charitable pursuits of the owner must be for the benefit of the public; and third, the use of the property must be exclusively devoted to those charitable pursuits." Id. at 558. In addition to fulfilling the three requirements of York Rite, supra, an organization seeking an ad valorem exemption under subsection (a) (4) must also fulfill the requirements of OCGA 48-5-41 (d) (2). This subsection provides: With respect to paragraph (4) of subsection (a) of this Code section, a building which is owned by a charitable institution that is otherwise qualified as a purely public charity and that is exempt from taxation under Section 501 (c) (3) of the federal Internal Revenue Code and which building is used by such charitable institution exclusively for the charitable purposes of such charitable institution, and not more than 15 acres of land on which such building is located, may be used for the purpose of securing income so long as such income is used exclusively for the operation of that charitable institution. Id.