A Hazmat suit is a fully encapsulating garment worn as protection from hazardous materials or substances. Materials used to make such garments include heavy PVC or rubber and Tyvek, a paper-like material that has been treated to repel hazardous chemical, biological or radioactive materials. These suits may or may not include accompanying compressed breathing air supplies to aid the wearer with breathing under adverse conditions.

There are several kinds of Hazmat (Hazardous Materials) gear (or "bunny suits", as they are sometimes called), giving varying levels of protection, depending upon what material is being dealt with. There are two levels of protection, Level A and Level B. Level A suits are total containment suits, giving protection from all forms of chemicals: solids, liquids, and gasses/vapors. Level B suits are not airtight, so provide protection against solids and liquids splashed or on surfaces, but not vapors, gasses, or submergence. This gear allows specially trained firefighters to deal with substances which may be toxic, very caustic, etc., which their normal turnout gear and SCBA may not be sufficient to protect them from. The gear is also used by trained Hazardous Materials specialists who may not be fire fighters. Hazmat clothing does not normally provide protection against fire or explosion; in these cases flash protection must also be worn.

While wearing Level A protection, it is not uncommon for the environment inside the suit to be 20-30°F (11-17°C) hotter than ambient, and 100% humidity to develop within minutes of sealing up the suit. Because of this, medical monitoring is required before and after use of a suit.

Components

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Hazmat gear will usually be worn in several layers, making it even less comfortable to wear. Hazmat gear consists of an air- and water-proof oversuit, boots, gloves, and a hood. These pieces are often taped up, at the ankle and wrist, so that there are no gaps for dangerous agents to enter. After using this equipment in a hazardous environment, firefighters will have to be decontaminated before the protective gear can be removed.

First Layer

The first layer is often station wear or a one-piece Nomex jumpsuit. The jumpsuit seals snugly at the ankles, wrists, and neck, in case of fire exposure. Without this additional layer, the polymer fabrics of the jumpsuit would likely melt and stick to the wearer's skin. The back of the jumpsuit has a large patch identifying the wearer.

Second Layer

The next layer of defense is a Tyvek suit. This disposable suit provides a layer that is impermeable to most chemicals. In addition, the firefighter wears a SCBA unit, and carries a voice activated radio, because once sealed inside the outer suit, there is no way to reach any of this equipment. Tyvek booties cover boots, and an inner pair of Silver-Shield chemical protective gloves is put on over latex surgical gloves. At this point, "Level B" protection is in place. An optional cooling vest, which holds ice packs, can be worn to keep the wearer cool. Some firefighters also carry a knife, in the event that they have to get out of the suit quickly in an emergency. The suit is too heavy to tear through, and would have to be cut from the inside.

Outer layer

The outer layer is a completely sealed, Level A full encapsulation suit. The suit has a one way pressure bleed valve to let out the wearer's respiration. Even with this valve, the suits tend to blow up like balloons. When sealed up, the wearer is completely isolated from the outside atmosphere. Nothing should be able to get in, and, unfortunately, almost nothing (including body heat and sweat) can get out. These suits are comprised of up to a dozen protective layers.

Flash Suit

If the first three layers aren't enough, there is one more layer which can be worn if necessary, on top of everything else. This is a flash suit, worn to protect the wearer from fire and explosions. This outer layer would be worn in the unlikely event that a firefighter had to enter an explosive atmosphere, for example to rescue a victim inside. This is a situation which would normally be avoided at all cost, except when human life is in danger. Some Level A suits have flash protection built in, but at the expense of greatly increased cost.

If everything is being worn, the wearer has five layers of hand protection, five layers of foot protection, and is looking through three layers of protective windows. As a result, while extremely protective, they are very uncomfortable and difficult to work in.

These suits can cost anywhere from $800 - $10,000 each, and may need to be disposed of after one use, depending upon what they were exposed to and how contaminated they are.

Environmental suits