Personal Protective Equipment (cont.)
Hot and Warm Zone Equipment
The hot zone is immediately dangerous to life or health. Accordingly, level A personal protective equipment with self-contained breathing apparatus or supplied-air respirator is required for first responders or other personnel working inside the hot zone, where contact with hazardous materials is likely, including chemical gas or vapors, biological aerosols, or chemical and/or biological liquid or powder residue. Incidents occurring in enclosed spaces with poor ventilation increase the risk of inhalation.
The warm zone is an uncontaminated environment into which contaminated victims, first responders, and equipment are brought. In classic HAZMAT (hazardous materials) response, the warm zone is adjacent to and upwind from the hot zone. However, experience with previous disasters indicates that contaminated victims capable of fleeing the hot zone are likely to bypass emergency medical services and go directly to the nearest hospital, in which case the warm zone may occur outside the emergency department or even inside the hospital.
Accordingly, the warm zone poses a risk of exposure to contaminated victims and equipment, which in turn depends upon the type and route of exposure. In general, early recognition of the type of exposure is based on the signs and symptoms that the victims show.
The protective equipment required depends on whether victims were exposed to a biological, chemical, radiological agent, or unknown agent or agents. The route of exposure may be inferred from the presence of contaminant on the clothing and skin of victims.
Vapor or aerosol exposure leaves no or minimal contaminant on victims, and material breathed into the lungs is not exhaled to contaminate others. Liquid or powder exposures may leave visible residue. For example, in the Tokyo subway sarin attack in 1995, about 90% of the victims exposed to sarin vapor reported to medical facilities by private or public transportation without contaminating others. Fortunately, secondary injury to hospital staff was minimal (mostly eye irritation) and did not require specific treatment. In a similar manner, handling victims exposed to biological aerosols poses little risk to emergency care personnel outside the hot zone.
- Known biological warfare agent hazards
- Personnel handling victims contaminated with biological warfare agents (BWA) require respiratory protection. Skin protection is largely unnecessary, because BWAs are not active through unbroken skin (with the single exception of the mycotoxins).
- Personnel handling victims who have been exposed to a known BWA aerosol are not required to wear protective equipment because secondary aerosolization of residual agent from clothing, skin, or hair is insignificant.
- When victims are contaminated with a known BWA liquid or powder, level D (universal precautions) and PAPR with HEPA filter are required until decontamination is complete. Level C personal protective equipment and PAPR with HEPA filter may be considered if the residue on victims is suspected of containing mycotoxins.
- Known chemical warfare agent hazards
- Personnel handling victims contaminated with chemical warfare agents (CWA) require respiratory and skin protection.
- When victims are exposed to a known CWA gas at standard temperature and pressure (such as chlorine, phosgene, oxides of nitrogen, cyanide), no personal protective equipment is required, because victims cannot breathe out hazardous gas and harm others.
- When victims are exposed to a known CWA vapor from volatile liquid (such as a nerve agent or blistering vapor), PPE is required, because responders may be exposed to low levels coming from the victims.
- When victims are contaminated with a known CWA volatile liquid, level C PPE with PAPR and chemical cartridge is required until decontamination is complete. In general, level C PPE is used when the inhalation risk is known to be below levels expected to harm personnel and when eye, mucous membrane, and skin exposures are unlikely.
- Known radiation hazards
- When victims are exposed to external radiation but not contaminated with a radiation-emitting source, no PPE is required. If any doubt exists whether victims or their clothing are contaminated, they should be surveyed with a Geiger-Müller counter.
- When victims are contaminated externally with radioactive material (on their skin, hair, wounds, clothes), use level D PPE (for example, waterproof barrier materials, such as surgical gown, mask, gloves, leg, and/or shoe coverings; universal precautions) until decontamination is complete. Double layers of gloves and frequent changes of the outer layer help reduce the spread of radioactive material.
- Handle radioactive materials with tongs whenever possible. Lead aprons are cumbersome and do not protect against gamma or neutron radiation. For this reason, experts currently recommend against their use when caring for a radiation-contaminated victim. Health care workers also should wear radiological dosimeters while working in a contaminated environment. The health care facility radiation safety officer usually supplies these devices.
- When victims are contaminated internally with radioactive material, wear latex gloves when handling body fluids (urine, feces, wound drainage). The health care facility radiation safety officer or health physicist can determine when the amount of radioactivity in the victim’s body secretions has fallen to a nondangerous level.
- Unknown hazards (biological, chemical or both)
- According to current US government (OSHA) regulations, level A PPE is required for personnel responding to an unknown hazard. Recommendations for hospital personnel are not yet clearly defined. SCBA in the hospital setting is more cumbersome to use than SAR. Some experts maintain that level C PPE with PAPR (with organic vapor cartridge and HEPA filter) provides adequate protection until decontamination is complete. Unfortunately, no single ensemble of PPE can protect emergency care personnel against all hazards.
Jeffrey L Arnold, MD, FACEP
Francisco Talavera, PharmD, PhD
Raymond J Roberge, MD, MPH, FAAEM, FACMT
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