In case of an emergency, the board may, by resolution passed by a four-fifths vote of all its members, declare and determine that public interest and necessity demand the immediate expenditure of public money to safeguard life, health, or property, and thereupon proceed to expend or enter into a contract involving the expenditure of any sum needed in the emergency without observance of the provisions requiring contracts, bids, or notice. If notice for bids to let contracts will not be given, the board shall also comply with Chapter 2.5 (commencing with Section 22050).