Before choosing a disinfectant, companies should consider the work being performed in the facility, the effectiveness of the disinfectant, how it will be applied, how it might impact the air handling system, and what contamination, if any, it might create in the room. Companies may end up using multiple disinfectants, rotating them and treating them more often for the greatest effectiveness. In most BL3 or BL4 biosafety facilities, paraformaldehyde is used to decontaminate a lab or a room. While it is strong enough to kill highly infectious and potentially toxic organisms economically, it is also more dangerous to personnel than other disinfectants. Air handling systems must be designed to contain the formaldehyde per federal regulations, and personnel must wear protective clothing when using it. Other disinfectants are chlorinated or chlorine derivatives, which also pose high risks to humans. And instead of killing an agent, they may help create a more complex or potent material than the one they were meant to kill. Vaporized hydrogen peroxide is an option that can be effective in small, confined spaces. Peroxide is attractive because it is relatively benign, but it may not be as effective for the more serious agents. Another decontamination consideration is autoclaving requirements for solid or infectious materials.