C1 – Environments found inside heated or air-conditioned buildings with clean atmospheres
C2 – Includes dry, rural areas, remote from the coast or sources of pollution and interior environments where some condensation may occur
C3 – City, industrial and coastal environments with moderate sulphur dioxide and salt exposure interior environments with high moisture levels
C4 – On the coast extending up to 1km inland and aggressive industrial environments, interior environments that are exposed to significant moisture and contamination e.g. indoor swimming pools.
C5 – I – Aggressive industrial areas where the environment may be acidic with a pH of less than 5
C5 – M – This category is offshore and on the beachfront in regions of rough seas and surf beaches
