Table 2.9.

Control classes and frequency of reassessment and monitoring (eight-hour exposure) (numeric values in the parentheses indicate the range of permissible changes)

Reassessment and re-monitoring	Control class (previous rating)
	3	2B	2A	1C	1B	1A
*Risk reduction measures shall be implemented with priority. Reassessment and monitoring at this frequency is limited to special cases. Please refer to the main text.
Reassessment	6 months*	6 months*	6 months (6 months to 1 year)	6 months (6 months to 2 years)	1 year (1 to 3 years)	2 years (2 to 3 years)
Re-monitoring	6 months* (6 months to 1 year)	6 months* (6 months to 1 year)	6 months (6 months to 2 years)	1 year(1 to 3 years)	2 years (1 to 3 years)	3 years (1 to 5 years)