The main environmental threats to a camera — particularly one that is installed outdoors — are cold, heat, water and dust. Housings with built-in heaters and fans (blowers) can be used in environments with low and high temperatures. In hot environments, cameras can be placed in enclosures that have active cooling with a separate heat exchanger.
To withstand water and dust, housings (often with an IP66 rating) are carefully sealed. In situations where cameras may be exposed to acids, such as in the food industry, housings made of stainless steel are required. Some specialized housings can be pressurized, submersible, bulletproofed or built for installation in potentially explosive locations. Special enclosures may also be required for aesthetic considerations.
Other environmental elements include wind and traffic. To minimize vibrations, particularly on pole-mounted camera installations, the housing should ideally be small and securely mounted.
The terms “indoor housing” and “outdoor housing” often refer to the level of environmental protection. An indoor housing is mostly used to prevent the entry of dust and does not include a heater and/or fan. The terms are misleading since the location, whether indoor or outdoor, does not always correspond to the conditions at an installation site. A camera placed in a freezer room, for example, will need an “outdoor housing” that has a heater.
The level of protection provided by enclosures, whether built-in or separate from a camera, is often indicated by classifications set by such standards as IP, which stands for Ingress Protection (also sometimes known as International Protection) and applicable worldwide; NEMA (National Electrical Manufacturers Association) in the U.S.; and IK ratings for external mechanical impacts, which apply in Europe. When a camera is to be installed in a potentially explosive environment, other standards — such as IECEx, which is a global certification, and ATEX, a European certification — come into play.