ATEX zones for gases/vapour:

Zone 0 (gases/vapours): an area in which an explosive mixture is continuously present or present for long periods.

Zone 1 (gases/vapours): an area in which an explosive mixture is likely to occur in normal operation.

Zone 2 (gases/vapours): an area in which an explosive mixture is not likely to occur in normal operation and if it occurs it will exist only for a short time.

ATEX zones for dust:

Zone 20 (dusts): an area in which an explosive mixture is continuously present or present for long periods.

Zone 21 (dusts): an area in which an explosive mixture is likely to occur in normal operation.

Zone 22 (dusts): an area in which an explosive mixture is not likely to occur in normal operation and if it occurs it will exist only for a short time