How often do I need to conduct toxic substance monitoring for my workplace?

The frequency of monitoring depends on the level of contaminant compared against the Permissible Exposure Limit (PEL) stated in the the WSH (General Provision Regulations) First Schedule.

The recommended frequencies are:

Ratio (in %) of concentration of contaminants compared to PEL	Frequency of monitoring
< 10% of PEL	No monitoring is required. A re-assessment should be carried out if there is any change in the process.
10% to 50% of PEL	At least once a year.
> 50% to 100% of PEL	At least once every 6 months.
> 100% of PEL	At least once every 3 months, until the exposure is reduced to be below the PEL by appropriate control measures.

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