The threat of bioterrorism

April 30, 2003
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While public figures fretted over what to do in the face of biological terrorism, safety and security professionals were developing protocols from good common sense safety science. Taking a proactive stance, equipment manufacturers and suppliers are working with these professionals to develop the standards for the selection and use of protective clothing and respiratory protection to keep first responders safe from biohazards.

Protecting first responders

Planning is based on the same well-known criteria applied in the safety arena to protect workers against chemical and biological hazards. In a biological attack, if the agent is an unidentified substance at an unknown airborne concentration, first responders would be protected with EPA Level A, fully encapsulated chemical protective clothing and self-contained breathing apparatus (SCBAs). The airborne concentration in an attack will depend on the method used to release the agent. If the agent is released using an aerosol-generative device, airborne concentrations will be higher than if the agent is released without an aerosolization device (i.e. from a pressurized container, or from the force of an explosion).

As we learned from the anthrax attacks in October 2001, when the biological hazard was identified, responders could safely change to EPA Level B chemical protective clothing and finally to EPA Level C chemical protective clothing with N95 air-purifying respirators with HEPA filters. This level of respiratory protection is adequate to protect from tuberculosis and known concentrations of known biological pathogens. This is the same EPA Level C chemical protective clothing (with gloves and an air-purifying respirator) that is routinely used for known concentrations of lead and asbestos.

Of course, a biological attack is an unknown. Anything from anthrax, plague or tularemia is on the list of potential biological agents. However, smallpox contamination is considered the Most Credible Event (MCE). In that case, once it is known that it is smallpox and what the level of contamination is, an air-purifying respirator rated N95 with a HEPA filter will work, as long as the responder has been trained, fit-tested and medically approved to wear it and dons the appropriate EPA Level C chemical protective clothing.

Lots to consider

Training is a key to safety for all respiratory protection. Responders must be trained how to use the equipment and medically approved to wear a respirator. Medical evaluation ensures that the wearer is physically able to breathe while working in a respirator. Illnesses such as heart disease, emphysema or asthma may limit the user's ability to breathe while wearing a respirator and may result in potentially life-threatening health risks that may develop during a biological incident.

Fit-testing is important because a properly fitting respirator reduces user exposure by a factor of 50.

Going airborne

The Centers for Disease Control and Prevention (CDC) working with The National Institute of Occupational Safety & Health (NIOSH) scientists predict biological weapons will expose people to bacteria, viruses or toxins as fine airborne particles. These weapons infect through inhalation, with infection through respiratory mucosa or lung tissues; ingestion by contact with mucous membranes of eyes or nasal tissues; or penetration, through open cuts. Even very small cuts and abrasions, of which employees might be unaware, could provide a route of infection.

Military research on biological weapons and civilian research to control infections in hospitals show that organic airborne particles share the same physical characteristics in air or on surfaces, as do inorganic particles from hazardous dust. Since biological weapons are particles, they are not expected to penetrate materials of properly assembled and fitted respirators or protective clothing. So, the recommended minimum respiratory protection is a half-mask or a full-face air-purifying respirator with particulate filter ranging from a N95 respirator for hazards such as tuberculosis to a P100 respirator for hazards such as hantavirus.

First responders may use a full-facepiece respirator with P100 filter or powered air-purifying respirator (PAPR) with HEPA filters when it's determined that an aerosol-generating device was not used to create high airborne concentration, and spread was by a letter or package that can be easily bagged.

Non-respiratory factors

First responder protection from a biological hazard may also include gloves and booties to prevent skin exposures and contamination of other clothing. The type of clothing depends on the type of agent, its concentration and the route(s) of exposure. Pre-planning is a key to this protection since responders can only be protected if equipment is available, training is provided and the threat is properly recognized. Remember to detect before you decide to protect. If you can't detect, then protect to the maximum level (EPA Level A) for the best possible skin and respiratory protection.

Heat stress is a major concern when wearing Level A, B or C chemical protective clothing. Emergency and non-emergency personnel responding to HAZWOPER incidents are time-limited due to the heat stress that can become life threatening if it is not recognized and treated immediately. So, a work/rest schedule will be part of any first response effort.

After exposure to a biological agent, decontamination will be required for personnel, their equipment and the environment. It's not so different from the HAZWOPER standard. If you know the contaminate, you can decontaminate effectively using the appropriate decontamination protocol. Indeed it's expected that training for a potential biohazard event will be similar to the levels established for 29 CFR1910.120, the HAZWOPER regulation, for Awareness, Operations, and Technician levels.

Expect the unexpected

So, while people wonder what will happen if other weapons of mass destruction are used in the United States, safety and security professionals are applying the same technology proven successful in preventing industrial accidents and exposures. This is just another progression in quantitative hazard recognition and control. Once we take the proactive steps we already know about, identify what we think will happen, and determine what precautions we'll need to implement to be safe, we can "expect the unexpected."

The wild card is this: A second problem with terrorism is that an act of terrorism is likely to involve a primary and secondary event that involves more than one type of threat. In other words, just when you think it's over, a bomb explodes, or a chemical is suddenly released. The name of the game when responding to weapons of mass destruction is that no one type of technology or equipment covers everything.

SIDEBAR: In case of biological hazard. . .

  • Be prepared in advance by first providing training, fit-testing and medical approval for personnel wearing tight-fitting respirators.
  • Take no chances. If the hazard and/or the concentration of the hazard is unknown, use EPA Level A chemical protective clothing with a SCBA.
  • Determine the agent and the concentration of the agent released using quantitative methods. You must detect before you can protect!
  • Refer to the CDC, NIOSH or other accepted safety practices and information to select respiratory protection, agent detection and decontamination technology.
  • Provide work/rest schedules for workers in encapsulated suits.
  • Provide decontamination for personnel, their equipment and the environment.

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