Arsenic kitchen means a baffled brick chamber where inorganic arsenic vapors are cooled, condensed, and removed in a solid form.

Control device means the air pollution control equipment used to collect particulate matter emissions.

Curtail means to cease operations to the extent technically feasible to reduce emissions.

Inorganic arsenic means the oxides and other noncarbon compounds of the element arsenic included in particulate matter, vapors, and aerosols.

Malfunction means any sudden failure of air pollution control equipment or process equipment or of a process to operate in a normal or usual manner so that emissions of inorganic arsenic are increased.

Opacity means the degree to which emissions reduce the transmission of light.

Primary emission control system means the hoods, enclosures, ducts, and control devices used to capture, convey, and remove particulate matter from exhaust gases which are captured directly at the source of generation.

Process emissions means inorganic arsenic emissions that are captured and collected in a primary emission control system.

Roasting means the use of a furnace to heat arsenic plant feed material for the purpose of eliminating a significant portion of the volatile materials contained in the feed.

Secondary emissions means inorganic arsenic emissions that escape capture by a primary emission control system.

Shutdown means the cessation of operation of a stationary source for any purpose.