They are using a combination of Ozone and Hydroxyl generators. Ozone machines have been used for years to remove stubborn odors. The Key is you have to clean as well as you can and use the Ozone machine as the last step. It's kind of like, there is a big lump of stinky cheese in the middle of the room, or maybe Chavez is there, trying to get the cheese. You can Ozone all you like and you can temporarily remove the odor, but the cheese and Chavez are still there, stinking up the place. If you throw the cheese out the window, Chavez will probably follow it and you can turn on the Ozone generator and get rid of the last traces of that foul odor. Leave it on overnight. Hydroxyl generator are similar, they usually use ultraviolet light and take longer but people can stand the exposure. Ozone, you must remove all people and animals (Chavez) from the area.