A powered air-purifying respirator (PAPR) is a type of

respirator A respirator is a device designed to protect the wearer from inhaling hazardous atmospheres including lead, lead fumes, vapors, gases and particulate matter such as dusts and airborne pathogens such as viruses. There are two main categories o ...

used to safeguard workers against contaminated air. PAPRs consist of a headgear-and-fan assembly that takes ambient

air An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

contaminated with one or more type of

pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effect, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

, actively removes (filters) a sufficient proportion of these hazards, and then delivers the clean air to the user's face or mouth and nose. They have a higher assigned protection factor than filtering facepiece respirators such as

N95 mask An N95 respirator is a disposable filtering facepiece respirator or reusable elastomeric respirator filter that meets the U.S. National Institute for Occupational Safety and Health (NIOSH) N95 standard of air filtration, filtering at least 95% ...

s. PAPRs are sometimes called positive-pressure masks, blower units, or just blowers.

Description

The modularity of PAPRs allows them to be customized for different working environments. Regardless of type, a PAPR consists of: * some kind of headgear (mask or hood), * a powered (motor-driven) fan which forces incoming air into the device, * a filter (or multiple filters) for delivery to the user for breathing, and * a battery or other power source. The mask may be hard and tight-fitting, or flexible and loose-fitting. The former affords a higher level of protection, but is less comfortable. Tight-fitting PAPRs require a fit test in hazardous workplace environments, while loose-fitting PAPR users can avoid

OSHA The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...

fit test requirements in ''certain'' hazardous workplace environments (see OSHA's respirator assigned protection factors for more information). Loose-fitting PAPRs can be useful when a fit test for a tight-fitting respirator cannot be successfully passed, for example when

facial hair Facial hair is hair grown on the face, usually on the chin, cheeks, bottom lip and upper lip region. It is typically a secondary sex characteristic of human males. Men typically start developing facial hair in the later stages of puberty or adol ...

is present. Masks may be reusable or disposable. Some masks allow the full face to be seen by others, aiding in interpersonal communication. PAPRs have low breathing resistance, unlike filtering facepiece respirators such as

s. A PAPR may have adjustable air flow rates for added comfort. While they are often referred to as

positive pressure Positive pressure is a pressure within a system that is greater than the environment that surrounds that system. Consequently, if there is any leak from the positively pressured system, it will egress into the surrounding environment. This is in ...

masks, they are not true positive-pressure devices as overbreathing can overcome the pressure supplied by the fan.

Filters

PAPRs may be outfitted with mechanical filters for atmospheres with

particulate Particulate matter (PM) or particulates are microscopic particles of solid or liquid matter suspended in the air. An ''aerosol'' is a mixture of particulates and air, as opposed to the particulate matter alone, though it is sometimes define ...

contamination, with a chemical cartridge for atmospheres with toxic gases or vapors, or both in combination. PAPRs can provide an assigned protection factor between 25 and 1000 depending on the type, as compared to an

's assigned protection factor of 10. When comparing various makes and models of PAPR, the supporting documentation from each of the respective manufacturers should be consulted in order to confirm the APF value of each product. In the United States, HE (high-efficiency) filters are the main class of particulate filter used with PAPRs. These are 99.97% efficient against 0.3

micron The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

particles, the same as a P100 filter. PAPR HE filters used in industry are generally re-used until they are soiled, damaged, or reduce PAPR air flow below specified levels. In healthcare settings involving a live virus, CDC recommends that a practical replacement cycle be implemented.

Regulatory requirements

42 CFR 84

42 CFR 84, from 1995 to 2020, copies 30 CFR 11 rules for PAPRs. The following table lists the air flow requirements for

NIOSH The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury, illness, disability, and death. It ...

-approved PAPRs under Part 84.175. Tight-fitting PAPRs may be fit tested with the facepiece unpowered and in negative-pressure (under 29 CFR 1910.134) while loose-fitting PAPR fit test protocols have not been changed from 30 CFR 11. The following table lists the ratings for particulate ratings for Part 84 PAPRs. PAPR100 ratings were added in 2020. PAPR100-N is not designed to filter oil particulates, and the official color-coding for all three respirator types is magenta. A study has demonstrated that users carrying out physical work at intensities 80-85% VO2 max "over-breathe" loose-fitting PAPRs and has recommended an increase of air flow to 400 lpm, an approximately two-fold increase over NIOSH-approved values.

Usage

According to the NIOSH Respirator Selection Logic, PAPRs are recommended for concentrations of hazardous particulates or gases that are greater than the relevant

occupational exposure limit An occupational exposure limit is an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials. It is typically set by competent national authorities and enforced by legi ...

but less than the

immediately dangerous to life or health The term immediately dangerous to life or health (IDLH) is defined by the US National Institute for Occupational Safety and Health (NIOSH) as exposure to airborne contaminants that is "likely to cause death or immediate or delayed permanent adver ...

(IDLH) level and the manufacturer's maximum-use concentration, subject to the respirator having a sufficient assigned protection factor. For substances hazardous to the eyes, a respirator equipped with a full facepiece, helmet, or hood is recommended. PAPRs are not effective during

firefighting Firefighting is a profession aimed at controlling and extinguishing fire. A person who engages in firefighting is known as a firefighter or fireman. Firefighters typically undergo a high degree of technical training. This involves structural fir ...

, in an

oxygen-deficient atmosphere Inert gas asphyxiation is a form of asphyxiation which results from breathing a physiologically inert gas in the absence of oxygen, or a low amount of oxygen (hypoxia), rather than atmospheric air (which is composed largely of nitrogen and oxygen ...

, or in an unknown atmosphere; in these situations a

self-contained breathing apparatus A self-contained breathing apparatus (SCBA) is a respirator worn to provide an autonomous supply of breathable gas in an atmosphere that is immediately dangerous to life or health from a gas cylinder. They are typically used in firefighting a ...

or supplied-air respirator is recommended instead. PAPRs have the advantage of eliminating breathing resistance caused by unpowered negative-pressure respirators such as

s. This makes them usable by persons who are medically disqualified from negative-pressure respirators. Loose-fitting PAPRs may also be selected for people who cannot pass a fit test due to facial hair or other reasons. PAPRs have disadvantages in terms of

ergonomic Ergonomics, also known as human factors or human factors engineering (HFE), is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Primary goals of human factors engi ...

impacts, and they restrict

peripheral vision Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the ...

In healthcare

Because they provide higher assigned protection factors, PAPRs are suitable for use during aerosol-generating procedures and by hospital first receivers. In healthcare settings, CDC recommends cleaning of all components except the filter after each use; care must be taken to select PAPRs that are not damaged or deteriorate due to cleaning and disinfecting agents. Racal Space Suits

In healthcare, a product known as the Racal suit can be used, consisting of a plastic suit and a PAPR fitted with HEPA filters. They were used by the U.S. Army Aeromedical Isolation Team to perform

medical evacuation Medical evacuation, often shortened to medevac or medivac, is the timely and efficient movement and en route care provided by medical personnel to patients requiring evacuation or transport using medically equipped air ambulances, helicopters and ...

s of patients with highly

infectious disease An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

For CBRN defense

Some PAPRs have special certification for chemical, biological, radiological, and nuclear contaminants (CBRN). In the United States, they must be certified to resist permeation of chemical warfare agents, which may involve additional protective coverings; that gas or vapor will not pass through the filter before a specified amount of time; and its ability to fit a wide range of facial sizes and shapes. Under

(IDLH) conditions, tight‐fitting full facepiece gas mask respirators with canisters (those with "14G approval") with CBRN approval may be used for escape, but loose‐fitting hoods and cartridges (those with "23C approval") with CBRN approval may not. Neither may be used to enter an IDLH atmosphere. The 23C CBRN PAPRs also must not be used if liquid droplet exposure occurs.

References

Sources from NIOSH

Sources from the Federal Register (Titles 29, 42)

External links

{{Breathing apparatus, industrial, state=expanded Personal protective equipment Headgear Respirators