The control limit for asbestos is 0.1 fibres per cubic centimetre (f/cm3) of air measured over four hours for all types of asbestos (Regulation 2). The HSE emphasises that the control limit is not a “safe” level, and that exposure from work activities involving asbestos must be reduced as far below the control limit as possible. Respiratory protective equipment (RPE) must be ignored when assessing whether the control limit has been reached.