The disposal of monitoring equipment, computers, and anesthesia machines also poses problems for the environment. Chip factories in Silicon Valley have left a legacy of pollution, creating 29 superfund sites in Santa Clara County alone. However, machines and monitors contain recyclable metals such as stainless steel, aluminum, brass, zinc, nickel and copper. The challenge is to separate the recyclable metals from the non-reusable materials. It is important to arrange environmentally preferable disposal with hospital waste management. An independent metal recycling facility may be more successful at recovering metal parts. Older anesthesia machines and monitors can also be refurbished and sold to a lab, another health care facility or veterinary clinic. There are also medical missions that will accept used equipment.