Under Attack! Protecting EMS Personnel

On May 26, 2004, Attorney General John Ashcroft and FBI Director Robert Mueller warned that credible intelligence from multiple sources indicates that al-Qaeda plans to attempt an attack on the United States in the next few months. While the focus was on upcoming major events like the political conventions, they also stated that law enforcement was concerned that terrorists could target so-called soft targets in the United States, such as shopping malls, hotels and transportation hubs. Given this current reality, EMS responders, whether in a metropolitan area or a small town, need to be prepared for such an event.

The first element of preparation is to understand the nature of the threat that you are facing. EMS personnel arriving at an attack site must be protected so they can deliver treatment to victims and not become a casualty of the event. This means they must have adequate training in the use of and access to personal protective equipment (PPE). EMS responders should also be aware of their surroundings in the event a secondary attack occurs after their arrival. For example, a car bomb explosion may be a cover for a subsequent secondary release of a biological agent. In Israel, EMS and police personnel arriving at a scene have routinely become targets for secondary events by terrorists. That same scenario could become reality in our country as well.2

Nature of an Attack

The level of PPE required will be determined by the nature and severity of the attack and the level of threat each situation presents. EMS personnel need to understand what agents might be used, how they could be delivered and what the potential targets are in their area. When a biological or chemical attack occurs, it may not be readily apparent what agent has been used.

In a chemical attack with a high dose of agent, people will immediately show signs such as choking, respiratory failure, burning eyes and skin, etc. This situation calls for using the highest level of personal containment for the EMS responder.2 This includes a fully encapsulated suit and self-contained air system as described in Table I, Level A.

However, at lower concentrations, some agents like phosgene or the blister agent mustard gas may not show toxic effects for 2¡V6 hours after exposure. Exposed individuals may leave a scene, then go to a hospital or clinic hours later showing signs of exposure.

In a biological incident, the primary attack may be an overt event where individuals witness an agent being released by a spraying device, such as a truck equipped with an agricultural sprayer, a small airplane or a simple canister spraying device. However, a terrorist attack will most likely be a covert event where an agent is released into the ventilation system of a building, in a subway station or inside a sporting event. Here, a smaller, more manageable amount of agent can be released without detection. In a known attack situation, first responders will probably not know initially what agent has been released. In this situation, it is best to assume a ¡§worst case¡¨ scenario and use the highest level of personal containment, Level A, which requires a fully encapsulated suit and self-contained breathing apparatus (SCBA).4 Since the incubation period for most biological agents ranges from 2¡V20 days in a covert attack, the site will remain unknown until clusters of victims all exhibiting the same symptoms begin to show up at hospitals. Identifying common activities and geographic locations of these individuals over the past few days will allow the exposure to be traced back to a specific location;5 however, it is important to realize that people may have left the exposure site and traveled to a wide variety of locations. Thus, it is important for medical and EMS staff to be in contact with their counterparts in nearby cities and towns to try to identify other foci of similar illness in individuals who might then be traced back to the same site (i.e., a basketball game or mall). With the passage of time, most biological agents will eventually deteriorate in the environment and be largely rendered inactive by the time the site is identified. The rate of deterioration is dependent on weather conditions (how hot or wet it has been), whether an attack was inside or outside, and the method for preparation of the agent. For example, freeze-dried bacteria or spores will persist for longer periods of time in dry conditions. Some organisms like Brucella suis, one of the species causing brucellosis, are stable for long periods of time in wet ground or on food.6

In a biological attack where the agent is known, such as anthrax or smallpox, victims and exposed EMS personnel and other first responders should undergo the established prophylactic treatment scheme defined by the Strategic National Stockpile (SNS) Program¡Xthe national repository for pharmaceuticals, vaccines and other medical materials established to meet such emergencies.7 This program is managed jointly by the Department of Homeland Security (DHS) and the Department of Health and Human Services (HHS) and is headquartered at the Centers for Disease Control and Prevention in Atlanta, GA.

When PPE Is Required

In the past, most medical emergencies have required personal protection precautions like gloves and a face shield or mask to protect against bloodborne disease. However, in a terrorist attack with chemical or biological agents, depending on the agent, level of hazard and the task an individual is to perform, required PPE may range from minimal to full-body protection.5 Performing routine emergency first aid procedures will be hampered by the constraints of full-body protective clothing, so it is essential that EMS personnel practice their procedures under simulated attack conditions.

If the agent used is ricin or botulinum toxin, adequate protection would consist of a full-face respirator and latex-free gloves. These toxins do not penetrate the skin, so full-body protection would not necessarily be required. However, an attack with a chemical agent like sarin or an infectious agent like plague would require SCBA, face and eye protection and a form of protective clothing that would provide a barrier to protect the skin from cutaneous exposure.

Determining what is the appropriate level of protective gear for EMS first responders has been debated by various government agencies and EMS providers. The EPA/NIOSH/OSHA have jointly developed a classification system (shown in Table I) that sets general levels of protection.5

Handheld detection devices can be used to detect the presence of certain chemical or biological agents like ricin toxin; however, they should be used only for a preliminary screen.8 A positive result may indicate an agent¡¦s presence, but a negative result cannot rule it out until more definitive results are obtained from a certified laboratory. A positive result can give some guidance about the level of PPE to employ.

An important factor in deciding the appropriate PPE for EMS personnel is determining where in the attack site they will be operating. In the conventional hazmat response to an incident there are three zones identified: hot, warm and cold.9

The hot zone is the primary zone of attack where the potential for exposure to biological/chemical aerosols or liquids is greatest. This area generally requires Level A PPE with SCBA or supplied-air respirators, depending on the level of threat presented by the agent present¡Xi.e., nonabsorbed toxins like ricin would require less stringent coverage. In most cases, EMS responders will not be working in this area, since activity in this area is generally the responsibility of hazmat and firefighter personnel.

The warm zone is an area adjacent to, and usually upwind of, the hot zone. This is the area where contaminated victims are brought to undergo decontamination procedures and receive medical assistance. Decontamination showers are set up here and victims undergo decon procedures while EMS personnel provide medical care to patients.

The cold zone in classical hazmat incidents is a contamination-free area; however, in a biological attack, decontaminated victims may still be carrying an infectious disease with the potential to spread it to EMS personnel or others outside the area. In a covert biological attack, where exposure occurred days before victims became symptomatic, there is no purpose in undergoing decontamination procedures.

The type of PPE required in the warm and cold zones depends on the type and route of exposure and whether the agent has been identified. In the warm zone, if the agent is unknown, current OSHA regulations require Level B PPE for EMS personnel (see Table I). Here, full respiratory protection is required, but a nonencapsulated suit, or so-called ¡§splash suit¡¨ that is chemically resistant, can be worn. This allows EMS workers more flexibility in performing their jobs than they would have in a cumbersome fully encapsulated suit.

If victims are exposed to a biological agent and an attack is ongoing, EMS personnel would require respiratory protection. If victims are presenting with symptoms days later, respiratory equipment would not be required, unless the agent was one that can be disseminated secondarily by respiratory routes, such as plague, tularemia and the viral hemorrhagic fever (VHF) viruses. Dermal protection with a full-body suit is required with highly lethal agents that can be transmitted through contact with lesions or bodily secretions, such as Ebola virus, Lassa virus, smallpox and plague. Victims exposed to fresh aerosols of biological agents will have agent on their clothing before decontamination; thus there is a risk to the EMS worker from secondary aerosolization exposure. In the Brentwood postal facility in Washington, DC, where anthrax-containing letters were processed, secondary aerosols of anthrax spores were still present in the air many days after the sorter was cleaned with topical bleach and more than 1.2 million letters were processed.10 Gloves should be worn at all times when handling contaminated or decontaminated victims.3

If the agent used in the attack is a known chemical agent, Level C PPE protection (see Table I) is required if you are dealing with living people.3 A SCBA or SAR respirator, gloves, splash suit and boots are necessary to keep all areas of the skin covered. With some agents like chlorine, cyanide or phosgene, the likelihood of off-gassing is potentially significant and can cause symptoms in exposed workers. With nerve agents like sarin (GB), off-gassing from victims¡¦ clothing is quite likely and can expose EMS workers to these agents.3 With the agent VX, which is the least volatile of the nerve agents, off-gassing is not a concern but dermal exposure must be controlled because of its capacity to readily penetrate dermal and mucous membranes.

Range of PPE Equipment Available

There are many types of PPE equipment available. To date, there is no consensus in the EMS community about required PPE at various levels of hazards and which equipment is most suited for maximal protection of EMS personnel. Table II provides a list of appendices to a National Institute of Justice report that describe available respiratory equipment, protective clothing and other gear by type, manufacturer, specifications and certifications.11,12 In February 2004, the Department of Homeland Security adopted a set of standards that combined features of NIOSH and NFPA standards for respirators and protective suits.13 EMS personnel must follow the OSHA 1910.134 standard for respiratory programs, fit testing, etc.14 EMS teams must become familiar with these regulations and requirements through approved 40-hour OSHA training courses. This is especially true for the requirements for an initial and periodic medical evaluation, initial and periodic face-fit test and ¡§fit-checking¡¨ every time a respirator is used. For some reason, the Department of Homeland Security is not currently stressing the need to follow these regulations, but they are absolutely essential to the safety of the EMS responder.

Masks and Headgear

Respirator protection is probably the most important component of the EMS worker¡¦s PPE regimen.3 There are two basic types of respirators: air-filtered and air-supplied. An air-filtered respirator consists of a facepiece or mask that covers either the nose and mouth or full face, and has a filter element attached that filters ambient air before it is breathed by the wearer. Filter cartridges vary in composition from those that simply filter out particles to those that filter organic vapors and oils as well. All filter cartridges have a finite lifetime after which their efficiency deteriorates. This lifetime is determined by the load of contaminating material that the filter can sustain.

Loading is determined by the concentration of contaminant in the air, type of contaminant, ambient humidity and weather conditions, and work intensity of the user. Increased work intensity, as in a disaster situation, increases the wearer¡¦s pulse and breathing rates. The increased breathing rate draws a large volume/velocity of air through the filter, which affects its filtering efficiency. When the loading capacity of a filter is exceeded, the filter will fail and be breached by harmful agents or chemicals.

General-purpose filters are not as effective as filters designed for specific agents or applications; however, in most cases, you will not know the agent used and therefore will not be able to select an appropriate special filter. The filter units are disposable and should be replaced after each use, or when they have reached their maximum load capacity. In a terrorist attack, especially where the nature of the agent will most likely be unknown, respirators should be able to filter both organic vapor and aerosol droplet nuclei. Thus, the filter needs to be a HEPA filter, rated to block all particles and droplets at 99.97% efficiency, or an N-100 rating. This will block aerosolized infectious agents, which are normally in the size range of 1¡V5 micrones.13

Respirators may be unpowered, in which case the wearer draws the air into the unit himself, or powered, in which a small battery-operated pump takes in air, passes it under pressure through the filter and into the facemask. The powered unit puts less breathing burden on the wearer, especially under high-work intensity conditions.

The second type of respirator is the supplied-air respirator, or SAR, which is equipped with a full faceshield covering the nose, mouth, eyes and remainder of the face. These are required in the hot zone, and sometimes in the warm zone, if victims are contaminated with unknown biological or chemical agents. Supplied-air respirators (SAR) have a facepiece similar to the SCBA unit, but are connected by a hose to an external pressurized clean air source. SAR units are less cumbersome to wear than SCBA units, afford the wearer more maneuverability, and last for a much longer time than SCBA units. However, there is always a risk of the hose being cut or entangled on something, trapping the wearer and potentially exposing him to an attack agent.

A recent addition to the respiratory protection area has been the introduction of flexible hoods with a filter cartridge attached. These units can be stored in a small space and, in an emergency, taken out and put over the head so the wearer can breathe filtered air while escaping from a released agent. The hoods have an elastomer neck seal, so one size fits all individuals and gives clothing a good seal.15 While these are crude air filtration devices, they could be used to provide rapid, temporary protection and escape from an area if a secondary release of agent occurs.

Protective Clothing and Gloves

In general, protective suits have been developed to protect against chemicals or chemical warfare agents. Intact skin is an effective barrier against most biological agents, with the exception of mycotoxins developed as bioagents, which can penetrate the skin. The anthrax bacillus cannot penetrate intact skin, but will infect lesions and abraded skin. However, most chemical agents were developed to be readily absorbed through intact skin, making that one of their primary routes of exposure.

The typical hazmat suit is constructed of multiple layers of various materials, each providing protection against a wide variety of hazardous materials. A thin sheet of aluminum is used in many suits to provide an impermeable barrier to organic vapors. This is especially effective in protecting against chemical nerve agents3 and can also protect against radiation from low-level alpha and beta particle emitters. Maximum protection, as required in the hot zone, is provided by the fully encapsulated suit.

In situations where skin exposure is not a concern, the standard hazmat-type splash suit, which provides protection from liquids, is generally used. An array of suits made from various impervious materials are available. A variety of other items round out the apparel required in a chemical/biological emergency situation. These include chemical (agent)-resistant gloves, hats or hoods, boots or boot covers. Some of these items can be decontaminated; others are for one-time use and then disposed of.3

Additionally, interim recommendations for PPE selection are available from NIOSH and CDC at the following sites:

• www.cdc.gov/niosh/unp-intrecppe.htm
• www.cdc.gov/niosh/ncpc/ncpc2.html.

Decon Procedure for PPE

Decontamination after an episode to remove any particles of agent that have settled on the outside of PPE gear is essential before the equipment is removed. Decontamination of individuals in their full gear should be accomplished using a strong soap and water, followed by 0.5% sodium hypochlorite solution (household bleach: one part bleach to 10 parts water). Inspect equipment to ensure that seals and seams are not still contaminated with trace amounts of material. If they are, continue treating them. After removing PPE equipment, EMS personnel should shower using a large volume of water and a strong soap.16 All wash-down water from the decontamination procedure should be retained and further treated to ensure full decontamination before disposal. In many cases when a lethal agent is involved in the episode, the PPE equipment should be destroyed by appropriate means to ensure the safety of future personnel.

References

1. NBC News Services: AP: Terrorists may strike U.S. this summer, May 27, 2004. www.msnbc.msn.com/id/5061256.
2. Erich J. Extreme EMS: Training for terrorism response. Emerg Med Serv 32: (3):2003.
3. Arnold JL. Personal protective equipment. e-medicine January 2003, www.emedicine.com/emerg/topic894.htm.
4. KI4U.Inc. Chemical & biological attacks, detection & response, FAQ, June 2003. www.ki4u.com/Chemical_Biological_attack_Detection_Response.htm.
5. Committee on R&D Needs for Improving Civilian Medical Response of Chemical & Biological Terrorism Incidents. Chemical and Biological Terrorism, Chapter 3, www.nap.edu/html/terrorism/ch3.html.
6. SIU School of Medicine. Overview of potential agents of biological terrorism, infectious diseases. www.siumed.edu/medicine/id/current/bioterror.htm.
7. CDC Emergency Preparedness and Response. Strategic National Stockpile. www.bt.cdc.gov/stockpile/index.asp.
8. Hanson D. Ricin toxin: What law enforcement needs to know. Law Enforcement Technology, pp.16–22, August 2003.
9. Cox R. Hazmat, October 2003. www.emedicine.com/emerg/topic228.htm.
10. Dull PM, Wilson KE, et.al. Bacillus anthracis aerosolization associated with a contaminated mail sorting machine. Emerging Infectious Diseases, Vol. 8, CDC. www.cdc.gov/ncidod/eid/vol8no10/02-0356.htm.
11. National Institute of Justice. Guide for the selection of personal protection equipment for first responders, respirator protection. NIJ Guide 102–00, Vol. IIa, b, c, d, Nov. 2002.
12. National Institute of Justice. Guide for the selection of personal protection equipment for first responders, respirator protection. NIJ Guide 102-00, Vol. IIb, c, d, e, Nov. 2002.
13. U.S. Department of Homeland Security. Standards for personal protective equipment for first responders. Washington, DC, February 27, 2004.
14. OSHA. Respiratory protection standard and enforcement. 29CFR-1910.134. ww.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=12716.
15. MSA flyer. www.MSAFire.com.
16. CDC. Interim recommendations for the selection and use of protective clothing and respirators against biological agents. Emergency Preparedness & Response, 20/24/2001. www.bt.cdc.gov/documentsapp/Anthrax/Protective/10242001rotect.asp.