The experimental hazmat suit and hazmat darklight cowl were created at Big MT before the Great War. Described as an "experiment within an experiment," the new hazmat suits were issued to Sierra Madre Villa workers when the Cloud, a toxin also originating from Big MT, became a major problem for construction crews and to general health. Due to unforseen effects on the suit by the Cloud, the villa workers using the suits were trapped, and eventually mutated into the Ghost people seen in Dead Money.
The hazmat suit is said to be bulky and stiff, workers using the suit complaining about the lack of ventilation and difficulty understanding each other when wearing it, forcing the use of sign language to communicate. Due to the unprotected latches and the harsh chemicals in the cloud, many of the suits latches were rusted shut in a short amount of time exposed, forcing several suits to be cut open in order to get the villa workers out of them. Though the suit worked well against the elements and poison, it was useless when put up against the cloud, many workers are still dying in the suits and later mutating into ghost people because of it.
Wearing the helmet will give the wearer a night-vision effect. Unlike night-vision scopes, it does not turn off during the day. The effect is similar to Ghost Sight.
Unlike the suits used by the unfortunate Sierra Madre construction workers, the obtainable hazmat suit has practically no negative effects; it will not grow stiff in prolonged use, protects the wearer to the highest potential against hazardous chemicals and poisons, and the headgear will not affect speech in any way.
- Hazmat testing ground, the suit and the cowl can be found in a protected pod. The Courier must either find the hazmat pod security code (in the Z-43 innovative toxins plant) or shoot the field with an upgraded sonic emitter to gain access to them.
- Wearing the cowl while viewing any ending slideshow will cause the night vision effect to persist throughout the slideshow.
- The night-vision effect remains when switching to third-person mode.
- When the cowl is unequipped, the Courier will have a "dizzy effect" for a brief period, day or night.
- The suit, unlike the one worn by ghost people, has no gloves. This seems at odds with the intended purpose of the suit, which is to protect the wearer from hazardous materials in the environment. Additionally, the eyepieces of the ghost people's helmets glow solid green instead of bright yellow at the center and ringed with green.
- When donned by companions, the eyepieces of the cowl will not glow.
- Using Ghost Sight or Cateye with the darklight cowl brightens the night vision.
- This suit cannot be obtained by using the glitch though going into third-person mode and slowly rotating the screen in order to take things through walls; the option to take the suit is present, but trying to take the suit yields nothing.
- The Hazmat darklight cowl is based on the U.S. Navy M1-1-5 Optical gas mask.