
People outside sheltered locations in the Sierra Madre are exposed to low concentrations of the toxin. The lethal dose depends on the concentration. Most of the Cloud in Salida del Sol South can also be cleared. Parts of the Cloud can be dispersed in the streets of Puesta del Sol by reactivating the ventilation fans. The Cloud can be corraled and dispersed through the use of fans. It smells of copper, Old World gold, with a tinge of sulfur. It is blood red in color, with the consistency of a dust cloud. The Cloud is a self-replicating airborne toxin that's poisonous to living beings that causes a noticeable burning sensation in the lungs and can even enter the body through the skin. “ The alloy that makes up the Pre-War kitchen knives is unknown, and seems to have decayed in contact with the toxic cloud. He could then use modified REPCONN rockets to push out both the New California Republic and Caesar's Legion at Hoover Dam, and finally, let traces of it drift west to NCR territory. He also plans to use it as an offensive technology, unleashing it upon the Mojave, cutting it off from the rest of the world. It was intended to be used to reclaim the Mojave and destroy the New California Republic. Upon further research, Elijah decided to weaponize the Cloud as a weapon of mass destruction, to wipe the slate clean. When preliminary samples taken from air on the edges of the Sierra Madre yielded promising results, he set up a chemistry set to allow it to replenish itself and traveled to the Madre in person, to perform research onsite. Father Elijah, a disgraced Brotherhood of Steel elder, learned of its existence from Ulysses. It wasn't until the 23rd century that it became important once more. įor centuries, the Cloud protected the casino and the villa, killing scavengers or weakening them so that they would become another victim of the tribe inhabiting it, the hazmat suited ghost people. The maintenance crews who donned their hazmat suits and tried to fight it, succumbed to its effects, mutating and becoming the violent, savage guardians of the Sierra Madre. It became a grim, uncompromising guardian of its secrets. The Cloud gradually seeped into the area, climbing out of the damaged vents, eventually blanketing the area, blotting out the sun. When the Great War hit shortly afterward, it continued to work for a few more years, before finally giving up the ghost. However, despite the problems, the ventilation system was eventually restored to barely functional order. Much to the displeasure of the attending physicians, they cut themselves out of the suits with steak knives. The crewmen retreated and headed to the villa clinic to get medical attention.

However, traces of the dust cloud were present and eroded the metal of the suit's locks, exposing them to the Cloud and sealing them within. The teams managed to find the source of the problem in the main ventilation pipe. Although considered creepy by the maintenance crews, they allowed the crews to explore the ventilation system and try, in vain, to identify the source of the Cloud.

To deal with the problem, Sinclair negotiated with the Big MT executives for yet another technology: The Darklight hazmat suits. Hospitalized in the villa clinic, the damage to their health was extensive enough to put them out of commission for good. Workers in the area started choking and vomiting. The pipes backed up, spewing out the red cloud. The Cloud manifested itself for the first time when the cheap villa ventilation system ground to a halt, a victim of cutting corners and Mr. The Sierra Madre was the only testing ground that was protected by the Cloud, which was hardly a prize. Of course, he was not informed that he would be receiving more than just harmless prototypes. Sinclair likely saw no other way to get the technology he needed, as he was already teetering on the brink of bankruptcy when he started negotiating with the executives.

When Frederick Sinclair came to Big MT for technology to purchase for the Sierra Madre, he unwittingly signed a Faustian pact: Apart from holograms and matter recombinators, the Think Tank would also place the Cloud at the Sierra Madre, using the casino, villa and its inhabitants as guinea pigs in its experiments.

Created as an experiment by the Big MT execs, the Cloud is a product of the Z-43 innovative toxins plant located in the crater.
