A hazardous area is any area where an explosive atmosphere may occur at any time.
Such locations are divided according to the likelihood of an explosive atmosphere as follows:
 

Zone 0 is an area where an explosive atmosphere is present continuously or for long periods.

Zone 1 is an area where an explosive atmosphere is likely to exist in normal circumstances.

Zone 2 is an area where an explosive atmosphere is not likely in normal operation, & if it occurs, it will only exist for a short time.

The requirements for an explosion are:

• A Flammable Vapour

• Availability of Oxygen

• A source of ignition

 

This illustrates a typical example of how Hazardous Areas are classified.