It has been many years since the first concerns for firefighter exposure to blood-borne pathogens emerged. These worries were propelled by evidence that firefighters and other first responders were repeatedly exposed to blood and body fluids contaminated with infectious diseases as part of rescue and emergency medical activities. Since then, there have been documented cases of first responder exposure to tuberculosis and SARS, while pandemic bird flu is on the horizon, too.

Coupled with the prospects for terrorism involving biological agents, such as anthrax and plagues, the protective clothing industry has evolved to meet many of these threats. And, it is still changing in an attempt to minimize potential exposure to the range of biological agents that are around today.

Biological agents can be split between liquid-borne hazards, such as those contained in blood and body fluids such as hepatitis and HIV, and airborne pathogens such as tuberculosis and SARS.

Generally speaking, protection from exposure to airborne pathogens is provided by respirators, while clothing in combination with eye/facewear provides protection to vulnerable areas of the body. This includes the body's mucous membranes such as those in the eyes, nose, and mouth, or susceptible skin areas where there are cuts or abraded skin.

Protective clothing also plays a secondary role against airborne pathogens, keeping the skin and underclothing from being contaminated by those pathogens that can be spread by being reaerosolized or passed by physical contact.

Emergency calls
While SCBA provides the ultimate in respiratory protection from airborne biological threats, they are not worn on all emergency calls. In the case of emergency patient treatment, first responders typically rely on face protection that ranges from surgical masks to air-purifying respirators with particulate filters.

But surgical masks are not respirators and will provide little, if any, protection from airborne pathogens. They are not fitted to the individual's face and will permit some flow around the edges of the mask. These masks are designed mainly to assist with infection control to the patient, and to limit any of their blood coming into contact with the mouth and nose of the care provider.

In contrast, properly fitted particulate filtering facepieces are designed to filter out airborne pathogens. The most common of these, the N95 respirator, is what the Center for Disease Control recommends for protection against SARS and bird flu.

However, the International Association of Firefighters (IAFF) advocates that firefighters instead use the more efficient P100 respirators. These filter 99.97% of particulates compared to the 95% filtered by N95s, when evaluated in standardized tests prescribed by the National Institute for Occupational Safety and Health (NIOSH). The IAFF argues that more efficient facemasks are needed because it only takes one virus in some cases under the right conditions to cause infection.

Regardless of the type of NIOSH-certified respirator used, all respirators must be selected by fit-testing, where the size and seal of the respirator is assessed for its effectiveness in preventing inward leakage.

When it comes to protective clothing, several advances have been made in first responder protection against liquid-borne pathogens. In the late 1980s, the Occupational Safety and Health Administration (OSHA) developed regulations for establishing requirements for employers to provide protection from blood-borne pathogens.

The goal of the resulting OSHA blood-borne pathogen standard was to provide working conditions that protect employees from being unnecessarily exposed to blood-borne pathogens. Under the standard, OSHA defined health care workers as including firefighters and EMS workers, who in the course of their duties can be reasonably expected to come into contact with blood and other potentially infectious fluids.

Appropriate clothing
The OSHA regulations require that employers such as fire departments provide appropriate protective clothing and equipment for their workers.
 
Appropriate protective clothing is further defined by OSHA as clothing that "prevents blood and other potentially infectious liquids from passing through to the wearer's skin or underclothing under the conditions of use and for the duration of time which the protective clothing will be used."

But the OSHA cannot establish specific criteria for protective clothing in all application areas, since the conditions and duration of use vary between occupations. For instance, normal conditions of use and the duration of use for an emergency responder and a surgeon vary greatly.

The protective clothing industry, through standards organizations, has developed key tests to demonstrate the effectiveness of clothing and materials used in the construction of clothing for preventing firefighter and other responder exposure to blood-borne pathogens.

These include a test for overall garment liquid integrity and a material test for viral penetration resistance. Both tests are needed to evaluate how clothing will function in providing firefighters and other first responders with protection from blood-borne pathogen exposure.

Viral penetration testing has been added to several protective clothing standards to address the concern that blood-borne pathogens can pass through clothing materials.

During the testing, sample clothing materials come into contact with a liquid containing a non-harmful surrogate microorganism to simulate the hepatitis B virus and HIV. After a defined period of contact, a sophisticated procedure is used to detect if any of the microorganisms penetrated through the material. The viral penetration resistance is so sensitive that it can detect a single penetrating virus, thus establishing the basis for clothing material viral-penetration resistance.

'Shower test'
The overall liquid integrity test is commonly called the "shower" test. As this name implies, samples of protective clothing are subjected to liquid spray exposure to assess the overall liquid protection provided by the garments.

The test is conducted with sample clothing, placed on a mannequin that is dressed with a liquid absorptive undergarment. The clothed mannequin is then sprayed with water treated with surfactant, a surface-active substance, at a specific concentration and for a specified duration. The surfactant is added to simulate the "better" wetting characteristics of chemicals and blood or body fluids. The liquid absorptive garment is then inspected to determine if any liquid penetrated the undergarment; garments that show no evidence of liquid penetration pass the test.

Like many other NFPA tests, this requirement is not intended to simulate actual firefighter exposures. The test is designed with relatively long liquid spray exposure, so that penetration into the garment can be readily detected by test. It is important for demonstrating overall garment integrity, because penetration tests on individual materials and seams cannot show how well the garment is designed and constructed to prevent liquid penetration.

The test is therefore useful in specifically assessing garment closure systems, seam quality and overall design integrity and other clothing features that are not evaluated in material testing. The combination of the integrity and material viral penetration tests demonstrate how clothing keeps blood and other potentially infectious liquids from contaminating the firefighter, in keeping with OSHA regulations.

These test approaches have been built into all NFPA clothing standards where emergency patient care can be expected as part of the first responder mission.

Such test requirements have been incorporated into the standards for structural/proximity firefighting (NFPA 1971), technical rescue (NFPA 1951), hazardous materials response (NFPA 1991 and 1992), first responder terrorism response (NFPA 1994), and emergency medical operations (NFPA 1999). The latter standard offers a range of garments, gloves, footwear, and face/eye protection devices for protecting emergency responders.

Due to their insidious nature, firefighters and other first responders must constantly be guarded against biological threats. The array of suitably tested and certified protective clothing and equipment, when properly selected and worn, can help minimize these threats.

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