Action level. An airborne concentration of inorganic arsenic of 5 micrograms per cubic meter (µg/m3) of air calculated as an eight-hour time-weighted average.

Authorized personnel. Individuals specifically permitted by the employer to enter the exposure control area to perform duties, or to observe employee exposure evaluations as a designated representative.

Breathing zone. The space around and in front of an employee's nose and mouth, forming a hemisphere with a 6- to 9-inch radius.

CAS (chemical abstract service) number. CAS numbers are internationally recognized and used on safety data sheets (SDSs) and other documents to identify substances. For more information see http://www.cas.org/about.

Day. Any part of a calendar day.

Designated representative. Any one of the following:

(a) Any individual or organization to which an employee gives written authorization.

(b) A recognized or certified collective bargaining agent without regard to written employee authorization.

(c) The legal representative of a deceased or legally incapacitated employee.

Emergency. Any event that could or does result in the unexpected significant release of inorganic arsenic. Examples of emergencies include equipment failure, container rupture, or control equipment failure.

Exposure. The contact an employee has with inorganic arsenic, whether or not protection is provided by respirators or other personal protective equipment (PPE). Exposure can occur through various routes of entry such as inhalation, ingestion, skin contact, or skin absorption.

Inorganic arsenic. Elemental arsenic (As), copper aceto-arsenite, and inorganic compounds containing arsenic (measured as As), except arsine. Inorganic compounds do not contain the element carbon.

Licensed health care professional (LHCP). An individual whose legally permitted scope of practice allows him or her to provide some or all of the health care services required for medical evaluations.

Permissible exposure limits (PELs). PELs are employee exposures to toxic substances or harmful physical agents that must not be exceeded. PELs are also specified in WISHA rules found in other chapters. The PEL for inorganic arsenic is an eight-hour time-weighted average (TWA8) of 10 micrograms per cubic meter (µg/m3).

Time-weighted average (TWA8). An exposure limit averaged over an 8-hour period that must not be exceeded during an employee's workday.