In this chapter, "designated public health disaster period" means a period:
(1) based on a threat to the public health, including a threat from:
(A) a chemical, biological, explosive, nuclear, or radiological attack or incident; or
(B) a communicable disease, epidemic, or pandemic;
(2) beginning on the earlier of the date:
(A) the governor issues a proclamation or executive order declaring a state of disaster under Chapter 418, Government Code, for any area of this state;
(B) the president of the United States declares a state of disaster that includes an area of this state as part of the federally declared disaster area; or
(C) a disaster described by Paragraph (A) or (B) occurs; and
(3) ending on the 30th day after the date the disaster declaration expires or is terminated.