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A hazmat suit (hazardous materials suit) is a piece of personal protective equipment that consists of an impermeable whole-body garment worn as protection against hazardous materials. Such suits are often combined with self-contained breathing apparatus (SCBA) to ensure a supply of breathable air. Hazmat suits are mostly used by firefighters, researchers, personnel responding to toxic spills, specialists cleaning up contaminated facilities and workers in toxic environments.
The United States Department of Homeland Security defines a hazmat suit as "an overall garment worn to protect people from hazardous materials or substances, including chemicals, biological agents, or radioactive materials." More generally, hazmat suits may provide protection from:
The hazmat suit generally includes breathing air supplies to provide clean, uncontaminated air for the wearer. In laboratory use, clean air may be supplied through attached hoses. This air is usually pumped into the suit at positive pressure with respect to the surroundings as an additional protective measure against the introduction of dangerous agents into a potentially ruptured or leaking suit.
Working in a hazmat suit is very strenuous, as the suits tend to be less flexible than conventional work garments. With the exception of laboratory versions, hazmat suits can be hot and poorly ventilated (if at all). Therefore, use is usually limited to short durations of up to 2 hours, depending on the difficulty of the work. Level A (United States) suits, for example, are limited by their air supply to around 15–20 minutes of very strenuous work (such as a firefighting rescue in a building).
However, OSHA/EPA protective level A suits/ensembles are not typically used in firefighting rescue, especially during a building/structure fire. National Fire Protection Association (NFPA) compliant "turnout gear", and NIOSH-certified SCBA, or CBRN SCBA, are the primary protection technologies for structure firefighting in the US.
Hazmat protective clothing is classified as either Level A, B, C, or D, based upon the degree of protection they provide.
Most suits used in Europe are covered by a set EU Norms, and divided into a total of six types (levels) of protection:
1: Can be used in places where the chemical in gaseous form isn't harmful to the body exterior.
Hazmat suits come basically in two variations: splash protection and gastight suits. As the name implies the splash protection suits are designed to prevent the wearer from coming into contact with a liquid. These suits do not protect against gasses or dust. Gastight suits additionally protect against gases and dust.
Such suits (level A in the US) are gas or vapor-tight, providing total encapsulation and the highest level of protection against direct and airborne chemical contact. They are typically worn with a self-contained breathing apparatus (SCBA) enclosed within the suit.
These suits are typically constructed of several layers and, being airtight, include a release valve so the suit does not overinflate from air exhaled by the SCBA. The release valve does retain some air to keep some positive pressure ("overpressure") inside the suit. As noted, such suits are usually limited to just 15–20 minutes of use by their mobile air supply.
With each suit described here, there is a manufactured device designed to protect the respiratory system of the wearer while the suit/ensemble is used to protect skin exposed to potential, or actual dermal, hazardous agents. That device is a respirator. A respirator may be something as simple as a headband strap filtering facepiece respirator (FFR), to a headharness negative pressure fullface respirator (air-purifying respirator/APR), to a full face, tight fitting, closed breathing air, or open circuit, self-contained breathing apparatus (CC-SCBA or SCBA).
Such suits (level B in the US) are not vapor-tight and thus provide a lesser level of protection. They are, however, worn with an SCBA, which may be located inside or outside of the suit, depending on the type of suit (encapsulating or non-encapsulating). They more closely resemble the one-piece Tyvek coveralls often seen used in construction and demolition work. Yet, Level B splash suits may also be fully encapsulating suits which are simply not airtight.
Lesser protection (level C in the US) suits may be coveralls of treated material, or multi-piece combinations, sealed with tape. This kind of protection is still "proof" against many non-invasive substances, such as anthrax.
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