'''2''': There are three area category types, with Category 1 requiring a very high level of protection and defined as an area having a permanent or prolonged risk of explosions (Zone 0), Category 2 which requires a high level of protection and has a frequent risk of an explosive mix being present in the air (Zone 1), and Category 3, specified as requiring a normal level of protection with a small chance of an explosive mix forming (Zone 2). | '''2''': There are three area category types, with Category 1 requiring a very high level of protection and defined as an area having a permanent or prolonged risk of explosions (Zone 0), Category 2 which requires a high level of protection and has a frequent risk of an explosive mix being present in the air (Zone 1), and Category 3, specified as requiring a normal level of protection with a small chance of an explosive mix forming (Zone 2). |