Personal Protective Equipment (cont.)
Civilian rescue or emergency care workers need personal protective equipment while they respond to contaminated environments or rescue contaminated people. Various types of emergency personnel require PPE, including first responders working in the hot zone (exclusion zone or contaminated area), emergency medical personnel involved in field decontamination (washing exposed people at the scene), and hospital personnel involved in decontamination at the hospital.
Doctors routinely use personal protective equipment to protect themselves against blood and body fluid exposure while caring for patients. They may use more specialized PPE when participating in prehospital response (usually as part of a specialized team) or when providing medical care to contaminated people at the hospital.
Many types of protective equipment are currently available, ranging from maximum protection with a positive pressure respirator and total body encapsulation to minimum protection with a simple surgical mask and a pair of latex gloves. These are the various types of protective respiratory devices and clothing.
Protective Respiratory Devices: The basic types of respirators are atmosphere supplying (self-contained breathing apparatus [SCBA], supplied-air respirator [SAR]) and air purifying respirator (APR).
- Self-contained breathing apparatus: SCBA consists of a full face piece connected by a hose to a portable source of compressed air. The open-circuit, positive-pressure SCBA is the most common type. This self-contained breathing apparatus provides clean air under positive pressure from a cylinder. The air then is exhaled into the environment. SCBA provides the highest level of respiratory protection.
- Supplied-air respirator: SAR consists of a full face piece connected to an air source away from the contaminated area via an airline. Because SARs are less bulky than SCBA, they can be used for longer periods. Supplied-air respirators are also easier for most hospital personnel to use. SARs, like self-contained breathing apparatus, provide a high level of respiratory protection.
- Air-purifying respirator: An APR consists of a face piece worn over the mouth and nose with a filter element that filters available air in the environment before inhalation. Three basic types of APRs exist: powered, disposable, and chemical cartridge or canister.
- Powered air-purifying respirators (PAPRs) deliver filtered air under positive pressure to a face piece mask, helmet, or hood, which provides respiratory and eye protection. Nonpowered air-purifying respirators operate under negative pressure, depending on the effort of the wearer who is breathing in to draw air through a filter. Because PAPRs function under positive pressure, they provide high-level respiratory protection.
- A variety of chemical cartridges or canisters, which eliminate a variety of chemicals including organic vapors and acid gases, are available.
- Disposable air-purifying respirators usually are half masks, which do not provide adequate eye protection. This type of APR depends on a filter, which traps particles in the outside air. The use of a high-efficiency particulate air (HEPA) filter alone or in combination with a chemical cartridge enhances disposable APRs. For exposures to biological agents in the air, PAPRs with HEPA filters are most efficient, followed by elastomeric half-mask HEPA filter respirators and non-HEPA disposable APRs. All air-purifying respirators are limited by the adequacy of their face seals, which may not fully seal tightly. Accordingly, APRs do not provide adequate respiratory protection in environments immediately dangerous to life or health
- High-efficiency particulate air filter: HEPA filters remove very small particles with an efficiency of 98-100%, efficiently excluding most aerosolized biological warfare agent particles. HEPA filters are incorporated into a variety of protective respiratory devices including PAPRs and elastomeric half-mask respirators.
- Surgical mask: Surgical masks in a medical setting are designed to protect the sterile field of the patient from contaminants generated by the wearer. Although surgical masks filter out large-size particles in the air, they offer no respiratory protection against chemical vapors and little against most biological aerosols.
Protective Clothing: Most protective clothing is aimed at protection against chemicals and chemical warfare agents. Skin (intact, not damaged) provides an effective barrier against all biological warfare agents except the trichothecene mycotoxins. This toxin is capable of causing burnlike lesions on the skin.
- Chemical-protective clothing: Chemical-protective clothing consists of multilayered garments made out of various materials that protect against a variety of hazards. Because no single material can protect against all chemicals, multiple layers of various materials usually are used to increase the degree of protection. Aluminum-lined, vapor-impermeable garments increase the level of protection. Protection is maximized by total encapsulation (completely covering the wearer). An assortment of types of chemical-protective hats, hoods, gloves, and boot covers are used with the garments.
- Barrier gown and latex gloves: Barrier gowns are waterproof and protect against exposure to biological materials, including body fluids, but do not provide adequate skin or mucous membrane protection against chemicals. Latex gloves also protect wearers from biological materials but are inadequate against most chemicals. Barrier gowns, surgical masks, latex gloves, and leg and/or shoe covers (used in hospitals and in operating rooms) together are called universal precautions.
Jeffrey L Arnold, MD, FACEP
Francisco Talavera, PharmD, PhD
Raymond J Roberge, MD, MPH, FAAEM, FACMT
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