Personal Protective Equipment
The term PPE (Personal Protective Equipment) refers to clothing and respiratory apparatus designed to shield an individual from chemical, biological, and physical hazards. This chapter includes a description of the types of PPE that address the needs of emergency workers, health care providers, and potential victims of terrorist attacks. It notes the general lack of access of many health care providers and potential victims to any kind of PPE. It also addresses the lack of specific regulatory standards for commercial PPE for use against military agents. Finally, the chapter discusses recently completed, ongoing, and planned research and development programs focused on PPE appropriate for response to terrorist attacks.
The chapter focuses primarily on protection from chemical agents, in part because of the fact that protection from hazardous chemicals will generally provide protection against biological agents as well, and in part because of the committee's belief that, by and large, biological agent incidents are not likely to be evident until well after release of the agent, at which point most agent not already in victims will have dissipated or degraded.
Types of PPE and Regulatory Standards
The amount and type of protection required in any hazardous materials incident depends upon the hazard and the duration of exposure anticipated, but a National Institute for Occupational Safety and Health
(NIOSH)/OSHA/EPA classification system is often used in describing general levels of protection:
OSHA requires Level A protection for workers in environments known to be immediately dangerous to life and health (i.e., where escape will be impaired or irreversible harm will occur within 30 minutes), and specifies Level B as the minimum protection for workers in danger of exposure to unknown chemical hazards. The NIOSH and the Mine Safety and Health Administration designate performance characteristics for respirators and provide approval for all commercially available respirators. Chemical protective clothing is not subject to performance standards established by a government agency, but the American Society for Testing and Materials (ASTM) has developed methods for testing the permeability of protective clothing materials against a battery of liquids and gases. The National Fire Protection Association (NFPA) has incorporated the ASTM test battery into the currently accepted standards for protective suits for hazardous chemical emergencies. Although a basic rule in selecting PPE is that the equipment be matched to the hazard, none of the ASTM permeability tests employ military nerve agents or vesicants. However, the NFPA is currently in the process of developing testing standards that will address the threat of nerve agents, cyanides, and vesicants.
Access to PPE
In the event of a chemical-agent incident, it is most likely that the first emergency personnel on the scene will be police or firefighters. The former will almost never have chemical PPE and should simply relay observations to the latter. Firefighter ''turnout" or "bunker" gear designed for fire
and heat resistance provides only minimal protection against hazardous chemicals, but firefighters often have sufficient respiratory protection (SCBA) available to allow for a rapid extraction and initial decontamination of victims at a location away from the primary source.
Hazmat teams have a small number of Level A suits. Recent data from tests of 12 different suits from six manufacturers by the Army's Domestic Preparedness Program (Belmonte, 1998) indicate that many commercially available Level A suits may provide good protection against nerve and mustard agents. The duration of protection will vary with individual fit, activity level, concentration of agent, and exposure route. Most, if not all, other NFPA-certified commercial Level A suits are likely to provide protection from most concentrations for at least brief periods. The current focus of Hazmat team activity is, in fact, short-term operations to control or mitigate a release, rather than sustained efforts locating and extracting victims or doing site remediation.
Emergency medical personnel most often have Level C PPE if they have any at all. This is likely to be appropriate for treatment of decontaminated victims, but unless the agent can be identified and its concentration established as nonlife-threatening, OSHA regulations would call for Level B protection.
A similar situation exists at local hospitals that may receive not only field-decontaminated patients but also "walk-ins," who may have bypassed field decontamination. Some authors have argued that Level C protection or even Level D protection (hospital gown, goggles, surgical mask, and latex gloves) is adequate for emergency department personnel; others argue for a universal PPE policy that will cover the exceptional cases (e.g., Level B in all cases until thorough decontamination is completed). Although the Joint Commission on Accreditation of Healthcare Organizations has established standards for hospitals calling for hazardous material plans and training, it does not specify details of either, and two recent reviews have suggested that most hospitals in the United States are ill prepared to treat contaminated patients (Cox, 1994; Levitin and Siegelson, 1996). A 1989 study of 45 California hospitals found that only two of the 45 actually had any personnel protective equipment assigned to the emergency department, and one of those two kept it in an ambulance that was not always at the hospital (Gough and Markus, 1989).
In the event of a chemical or biological terrorist act, there is a need to protect two main populationsthe responders/health care providers, and the victims. The following section will review potential advances and R&D needs for both of these groups.
Responders and Health Care Providers
Military PPE has been tested for protection against chemical weapons agents (e.g., one or more nerve agents, mustard, and lewisite), but generally does not have the certification by NIOSH or NFPA that would allow its purchase and use for any purpose by civilian workers. Some progress in addressing this impasse was made in conjunction with the Army's Chemical Stockpile Emergency Preparedness Program (CSEPP). In order to make recommendations for civilian emergency responders in communities adjacent to chemical weapons stockpiles (Argonne National Laboratory, 1994; Centers for Disease Control and Prevention, 1995a), CSEPP sponsored tests of commercial respirator filters (Battelle Laboratories, Inc., 1993), fabrics used in commercial chemical suits (Daugherty et al., 1992), and one commercially available splash suit (Arca et al., 1996) using nerve and mustard agents. Subsequent U.S. Army testing of four Level A suits, four Level B suits, and four Level C suits has resulted in approval of two Level A commercial suits for use in chemical agent emergencies at Army facilities and purchase of commercial Level A and Level C PPE by MMSTs (United States Army Chemical Demilitarization and Redemption Activity, 1994).
As a result of testing undertaken by the CSEPP program, a number of filter canisters for powered air purifying respirators (PAPRs) were shown to provide protection against exposure to chemical weapons agents. PAPRs allow greater mobility than SCBAs and might support responders performing decontamination and medical triage and treatment. However, in order to meet regulatory requirements, responders can use PAPRs only in an environment in which the level of exposure to chemical weapons agents can be measured. Not only must monitors be available, they must detect the chemicals at appropriate concentrations. The necessary concentrations are determined by the effectiveness of the respirator (designated by the protection factor assigned to the class of respirator) and the acceptable exposure limit for the contaminant. Protection factors are a measure of performance based on a ratio of the contaminant concentration outside the mask to the concentration inside the mask. The airborne exposure limit (AEL) is an 8-hour time weighted average of exposure, for a 40 hour work week. PAPRs as a class (at the air flow rate tested), are assigned a protection factor of 50 by NIOSH. PAPRs therefore can be used only when monitors can detect the chemical at a concentration fifty times the AEL for that chemical. Lack of practical monitoring equipment (easily used in the field) that can detect chemical weapons agents at the limits required results in difficulties meeting current regulatory requirements. Therefore, although PAPRs might provide adequate protection against
exposure to chemical weapons agents for some responders, SCBAs or in-line respirators are required to meet regulatory standards.
New insights into respirator design in the last few years have resulted in the development of improved respiratory protection. Protection factors appear to increase by an order of magnitude with a switch from a facemask to a hood design. Combining the hood-style mask with a blower unit has achieved even more significant results. One such mask currently in development under the U.S./Israel Agreement on Cooperative Research and Development Concerning Counter-Terrorism takes advantage of these combined technologies. The hood-style blower system achieved protection factors of 50,000 in the preliminary test results reviewed and is being designed for chemical/biological protection. The hood style also has the advantage of being a one-size-fits-all system. Continued efforts to develop this respirator technology and obtain regulatory approval for civilian emergency responders should be supported.
Cutaneous exposure to toxic liquids during a terrorist incident is a concern (the hazard to skin from vapor exposure is likely to be low). Protective suits tested against chemical weapons agent simulant (see above) are similar in basic design to those routinely used by civilian responders. The suits have some modifications, such as specially sealed seams, and are more expensive than similar suits that are not approved for use against chemical weapons agents. The suit testing program for commercial suits used the criteria identified for the military Joint Service Lightweight Integrated Suit Technology (JLIST) program, and results indicated that the commercial suit tested provided protection greater than the military's Battle Dress Overgarment (BDO).
Problems with suits remain and can include bulk, weight, and durability. Heat stress is a significant problem. The military has fielded suits with advantages over BDOs (for example SARATOGA system clothing). JLIST technology currently being fielded is expected to provide chemical/flame protection, reduced heat stress, increased durability, and the ability to be washed. Suits under development in the Advance Lightweight Chemical Protection program may offer even greater improvements. The program is based on selectively permeable membrane technology, and suits are expected to be lighter in weight, less bulky, and result in less thermal stress that JLIST garments. The National Aeronautics and Space Program has developed a prototype Level A suit as part of their Global NBC Emergency Response Technology Program that uses cryogenic air to provide for suit cooling as well as a larger air supply. Preliminary testing has suggested significant improvements in both heat management as well as work period efficiency and duration in simulated hazardous materials incidents.
Protection for Possible Victims of Terrorist Attack
Pocket-sized masks intended for victim rescue and self-rescue during chemical and biological incidents are available from several manufacturers (for example, Fume Free, Essex, Giat). One system uses layers of activated charcoal cloth to remove chemical toxicants and a particulate element for particle removal. Testing has shown the system to be effective against nerve agent simulant, hydrogen cyanide, and tear gas. The one-size fits all mask uses a hood design with a neck seal.
Equipment intended for use by the public was available and was used in Israel during the Gulf War. Improper respirator use resulted in some deaths (Hiss and Arensburg, 1994). Additional data were gathered on issues such as the psychological response of civilians during respirator use and physiological effects in children (Arad et al., 1994). Respirators intended for the public were subsequently redesigned to prevent accidental death and improve the efficacy and comfort of the equipment. Equipment developed in Israel included: hood-style mask and blower systems for civilian emergency responders; one size fits all hood and blower systems for adults and for children ages 3–7; and portable infant protection cribs.
Collective shelter is an alternative to individual protective equipment, but would be most useful in situations in which a specific group has been targeted (e.g., use by the military). Systems are available from a few manufacturers. Sheltering in place is an option for the general population when evacuation is not practical. UNOCAL Corporation, a large manufacturer of agricultural chemicals, has developed simple kits containing tape, plastic, a shelter-in-place video, and symptom cards and has distributed the kits to families and schools near their processing plants. Families can use the kits to quickly seal a room as a shelter. The approach appears cost effective. Other programs have been developed to educate the public about sheltering, which, in some circumstances, if undertaken too late or carried out improperly, may actually increase the exposure of those in the shelter. The "Wally Wise Guy" program, developed in Texas and now used in several other states, educates children about sheltering in place. Communities in Oregon and Washington near a chemical weapons stockpile have jointly developed an educational video on sheltering in place.
Areas in Need of Further Work
Generally, a range of equipment is available to protect both emergency responders and the general public during chemical and biological events. However, problems remain. One is lack of uniform testing standards for suits. Others, such as the potential for heat stress in many ensembles, should be a priority in current development programs. A possibility
being pursued by the U.S. military, for example, is the use of selectively permeable membrane technology.
One of the most significant problems remaining is the choice of respiratory protection by responders. This choice is inextricably linked to availability of monitors capable of measuring toxicants at levels that satisfy regulatory requirements. Without adequate monitoring equipment responders are limited to working in Level A PPE. This limitation imposes unacceptable training burdens and expense on many agencies. Level A ensembles also result in limited stay times where the toxic agent or its concentration is unknown, difficulties in treating patient due to the bulk of the ensemble, and greater potential for heat stress. It would be an advantage for health care providers to use Level B and C PPE. As discussed above, some Level C respirators (PAPRs) have been tested and would provide protection against chemical/biological agents. However, current chemical field detectors have inadequate sensitivity to support use of PAPRs in chemical agent incidents. Two approaches could mitigate the situation within the current regulatory framework. Fielding respirators with greatly increased protection factors, hood and blower systems for example, would raise the concentration level at which use of an SCBA is mandated. Current gross level monitors may then be adequate. The second approach is to increase the sensitivity of field detectors provided to responders so that the appropriate level of PPE can be chosen with confidence. A third approach would be to reassess current regulations for the occupational use of PPE, regulations that do not apply to the general public, in the specific context of emergency response situations. For example, current regulatory standards that are protective for chronic occupational exposures might be reviewed and special criteria developed. When the criteria are met hospital staff remote from an incident could potentially use PAPRs (supported by gross level monitoring) for short-term exposures.
Respiratory protection used in Israel for general public has been improved as the result of insights gained during the Gulf War. However, the risk to the public from chemical exposure needs to be balanced against the risks of respirator use from erroneous use. Improper use can result not only in loss of protection against the chemical but also in injury from use of the respirator itself, particularly in individuals with asthma or other respiratory disorders. Adequate warning time would be needed to distribute respirators to the public and to carefully educate people on their use. Hood and blower systems offer less risk to the public than other respirator systems and are available for adults and children. Respirator systems based on a facemask rather than a hood system would need to be fit for each individual to ensure a tight seal. These respirators can not be issued to citizens with facial hair. Blower units supply filtered air to the hood, thereby eliminating the need for the individual to actively pull air
through the filter and also ensuring that minor or temporary breaks in the hood-neck seal result in filtered air leaving the hood rather than contaminated air being drawn in. Batteries used in blower systems would require monitoring and eventual replacement, however, which increases the difficulty in maintaining a program for the general population. It is unlikely that early intelligence would be adequate to support distribution of respirators and education of the recipients. This and the other considerations discussed here make the option of providing respirators to the general public less attractive than either evacuation or some form of sheltering in place.
PPE Specifically for Biological Agents
Terrorist use of a biological agent presents very different needs for and uses of personal protective equipment than use of a chemical agent. Unless pre-incident intelligence leads responders to an incident prior to release of a biological agent, the majority of terrorist scenarios would likely involve a covert release of agent. Since most of the biologic agents have incubation times ranging from hours to weeks between exposure and manifestation of clinical symptoms, the majority of the biological agent aerosol is likely to have dissipated from the area of release prior to recognition by first responders that a biological incident has occurred.
With the exception of smallpox virus and to a lesser extent plague bacteria, person-to-person transmission of these diseases rarely occurs if "universal precautions" are maintained (e.g., gloves, gown, mask, and eye protection). The majority of infected patients can be cared for without specialized isolation rooms or specialized ventilation systems. Cohort nursing with the usual practice of universal precautions will provide adequate protection. The hemorrhagic virus infections may be transmissible via a respirable aerosol of bloodrespiratory protection of workers caring for these patients is required.
In the event that pre-incident intelligence puts fire and rescue personnel at the scene of a release, the same PPE they would employ for a chemical incident should serve to protect them from biological agents as well. Most of the infectious agents and toxins are most efficiently delivered as a respirable aerosol, so respiratory protection would be the primary means of protection from these agents. This can be accomplished by either self-contained supplied air breathing devices (SCBA) or high-efficiency particle respirators (HEPA filters). Eye protection and protective clothing sufficient to provide a barrier will protect from cutaneous infection with these agents. An exception to these biological protective equipment strategies is T-2 mycotoxin, which requires an approach similar to chemical agents (Wannamacher et al., 1991; Wannamacher and Weiner, 1997).
Protection of the first responders will likely involve barrier protection
similar to the equipment currently used for potentially infectious patients supplemented by SCBA or HEPA filters. It is important to note the current OSHA regulations for response workers require protection levels similar to those required for chemical agents. These regulations should be reevaluated for applicability in light of the risks posed by biological toxins.
Implementing these PPE strategies may prove difficult, as it is human nature to proceed to maximum protection when the perceived danger is unknown or unusual. It is important to emphasize basic principles of infectious disease control and emphasize the lack of person-to-person transmission for the majority of the biological agents when responding to such incidents, so as to maximize the available medical resources to provide care for the largest number of victims.
Research and development in personal protective equipment has yielded vastly improved protection for the military and, to some extent, civilian first responders. However, the use of even the most up-to-date respirator is greatly restricted by the necessity of air monitoring, time of exposure limitations, and relatively low protection factors. Civilian first responders are also hampered by the weight, size, and heat of the protective suits. Aside from issues surrounding the equipment itself, policy and regulation also influence use and effectiveness of personal protective equipment. As listed below, the committee recommends that research and development continue to focus on better and more effective equipment, but also recommends that current policy and procedures be reviewed as well.