(a) “County.” Any county of the first, second, second A, third, fourth, fifth, sixth, seventh and eighth class.

(b) “County board of health” or “board of health.” The board of any single-county department of health or the board of any joint-county department of health created under this act.

(c) “County department of health.” Any single-county department of health or any joint-county department of health created under this act. A county department of health shall consist of a board of health, a health director, and a staff of employees.

(d) “County health director” or “health director.” The health director of any single-county department of health or joint-county department of health created under this act.

(e) “Created.” A single-county department of health shall be considered to be created upon the enactment of a resolution by the county commissioners of the county, or upon the certification of a favorable vote on the question of creation at a referendum conducted in the county in accordance with section 5 of this act.²

A joint-county department of health shall be considered to be created upon the enactment of a resolution by the county commissioners of each participating county, or upon the certification of a favorable vote on the question of creation at a referendum conducted in each participating county, or upon the enactment of a resolution by the county commissioners of one or more of the participating counties and the certification of a favorable vote on the question of creation at a referendum conducted in the other participating counties in accordance with section 5 of this act.

(f) “Established.” A county department of health shall be considered to be established thirty (30) days after the county commissioners or, in the case of a joint-county department of health, the joint-county health commission, have given written notice to all the cities, boroughs, incorporated towns, and townships, within the territorial limits of the county or counties which have created the county department of health, that the State Secretary of Health has found, in accordance with section 9 of this act,³ that the county department of health is ready to exercise its powers and duties.

(g) “Joint-county health commission.” The combined boards of county commissioners of the several counties participating in a joint-county department of health.

(h) “Municipality.” Any city, borough, incorporated town, township of the first class and township of the second class.

(i) “Population.” This term means the number of residents, according to the most recent decennial census figures certified by the United States Department of Commerce that are available on the first of December of the year preceding the calendar year in which such figures are applied in accordance with sections 4, 20 and 25 of this act,⁴ except that when the State Secretary of Health finds that such figures do not accurately represent true population because of migration or changes in birth and death rates, he shall designate which estimates of population available from an agency of the Commonwealth or Federal Government are more accurate, and in such case the term “population” means the number of residents according to the most recent of the designated estimates available on the first of December of the year preceding the calendar year in which such figures are applied in accordance with sections 4, 20 and 25 of this act. No finding and designation of estimates made by the State Secretary of Health under this subsection shall be effective, unless he gives notice of such finding and designation to all county departments of health, and to municipalities eligible for State grants under section 15 of this act,⁵ before the first of January of the year in which the estimates are to be applied. During the calendar year one thousand nine hundred and fifty-one, the most recent decennial census figures certified by the United States Department of Commerce shall be used.