That APF (Assigned Protection Factor) is a critical knowledge point in your worker learning curve of handling or being near ANY CHEMICALS on site! An example of this is Hydrogen Sulfide Gas:
Eye/Face Protection: Wear chemical safety goggles. A face shield (with safety goggles) may also be necessary.
Skin Protection: Wear chemical protective clothing e.g. gloves, aprons, boots. In some operations: wear a chemical protective, full-body encapsulating suit and self-contained breathing apparatus (SCBA). Suitable materials include: Tychem® BR/LV, Tychem® Responder® CSM.
Up to 100 ppm:
(APF = 10) Any supplied-air respirator*.
(APF = 25) Any powered, air-purifying respirator with cartridge(s) providing protection against hydrogen sulfide.
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against hydrogen sulfide or Any self-contained breathing apparatus with a full facepiece.
*Reported to cause eye irritation or damage; may require eye protection.
APF = Assigned Protection Factor
Assigned Protection Factor (APF) means the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when the employer implements a continuing, effective respiratory protection program as specified by this section.
Maximum Use Concentration (MUC) means the maximum atmospheric concentration of a hazardous substance from which an employee can be expected to be protected when wearing a respirator, and is determined by the assigned protection factor of the respirator or class of respirators and the exposure limit of the hazardous substance. The MUC usually can be determined mathematically by multiplying the assigned protection factor specified for a respirator by the permissible exposure limit (PEL), short-term exposure limit, ceiling limit, peak limit, or any other exposure limit used for the hazardous substance.
The MUC for respirators is calculated by multiplying the APF for the respirator by the PEL. The MUC is the upper limit at which the class of respirator is expected to provide protection. Whenever the exposures approach the MUC, then the employer should select the next higher class of respirators for the employees. Employers must not apply MUCs to conditions that are immediately dangerous to life or health (IDLH); instead, they must use respirators listed for IDLH conditions in paragraph (d)(2) of this standard. When the calculated MUC exceeds the IDLH level for a hazardous substance, or the performance limits of the cartridge or canister, then employers must set the maximum MUC at that lower limit.
Respiratory hazards may be present in the workplace whenever an atmosphere does not contain sufficient oxygen, or if it contains chemical, biological, or radiological contaminants in sufficient quantity to harm the health of employees. Respiratory hazards may be present in the workplace in the following physical forms:
Dusts and fibers are solid particles that are formed or generated from solid materials through mechanical processes such as crushing, grinding, drilling, abrading or blasting. Examples are lead, silica, and asbestos.
Fumes are solid particles that are formed when a metal or other solid vaporizes and the molecules condense (or solidify) in cool air. Examples are metal fumes from smelting or welding. Fumes also may be formed from processes such as plastic injection or extrusion molding.
Mists are tiny droplets of liquid suspended in the air. Examples are oil mist produced from lubricants used in metal cutting operations, acid mists from electroplating, and paint spray mist from spraying operations.
Gases are materials that exist as individual molecules in the air at room temperature. Examples are welding gases, such as acetylene and nitrogen, and carbon monoxide produced from internal combustion engines.
Vapors are the gaseous form of substances that are normally in the solid or liquid state at room temperature and pressure. They are formed by evaporation. Most solvents produce vapors. Examples include toluene and methylene chloride.
Biological hazards include bacteria, viruses, fungi, and other living organisms that are respirable and can cause acute and chronic infections. Examples include Legionnaire’s Disease and animal waste products (e.g., feces).
Fit Factor (FF) A Fit Factor is a number that is the direct result of a quantitative respirator fit test. It is a measurement made by an instrument during a simulation of workplace activities (the exercises). It is expressed as the challenge aerosol concentration outside the respirator divided by the challenge aerosol concentration that leaks inside the respirator DURING A FIT TEST.
Workplace Protection Factor (WPF) A Workplace Protection Factor is the level of protection actually experienced by an individual while working in a hazardous environment. It is expressed as the concentration of REAL ambient hazard outside the respirator divided by the concentration of REAL ambient hazard that leaks into the respirator. WPF’s are usually measured by attaching personal sampling pumps to individuals while they go about their normal work activities. This technique is often used for conducting respirator research.
Assigned Protection Factors (APF) An Assigned Protection Factor is the level of protection that a particular type of respirator can be expected to provide 95% of the time. An APF of 10 means that type of respirator (if used properly) can be safely used in an atmosphere that has a hazardous concentration of up to 10 times the Permissible Exposure Limit (PEL) for that hazard. APF’s are determined by the government or a standards organization. In the United States, the National Institute of Occupational Safety and Health (NIOSH) and the American National Standards Institute (ANSI) both establish APF’s for various types of respirators. For example, a half face negative pressure air purifying respirator typically has an APF of 10. Most full face negative pressure air purifying respirators typically have an APF of 50. APF’s may vary depending on who publishes them, so be careful.