(1) For the purposes of this section, "air pollution control facilities" mean any treatment works, control devices and disposal systems, machinery, equipment, structures, property, property improvements, and accessories, that are installed or acquired for the primary purpose of reducing, controlling, or disposing of industrial waste that, if released to the outdoor atmosphere, could cause air pollution, or that are required to meet regulatory requirements applicable to their construction, installation, or operation.
(2) The tax levied by RCW 82.08.020 does not apply to:
(a) Sales of tangible personal property to a light and power business, as defined in RCW 82.16.010, for construction or installation of air pollution control facilities at a thermal electric generation facility; or
(b) Sales of, cost of, or charges made for labor and services performed in respect to the construction or installation of air pollution control facilities.
(3) The exemption provided under this section applies only to sales, costs, or charges:
(a) Incurred for air pollution control facilities constructed or installed after May 15, 1997, and used in a thermal electric generation facility placed in operation after December 31, 1969, and before July 1, 1975;
(b) If the air pollution control facilities are constructed or installed to meet applicable regulatory requirements established under state or federal law, including the Washington clean air act, chapter 70A.15 RCW; and
(c) For which the purchaser provides the seller with an exemption certificate, signed by the purchaser or purchaser's agent, that includes a description of items or services for which payment is made, the amount of the payment, and such additional information as the department reasonably may require.
(4) This section does not apply to sales of tangible personal property purchased or to sales of, costs of, or charges made for labor and services used for maintenance or repairs of pollution control equipment.
(5) If production of electricity at a thermal electric generation facility for any calendar year after 2002 and before 2023 falls below a twenty percent annual capacity factor for the generation facility, all or a portion of the tax previously exempted under this section in respect to construction or installation of air pollution control facilities at the generation facility shall be due as follows: