Where continuous forced air ventilation is used to mitigate a hazardous atmosphere, no employee shall enter the space until the ventilation has eliminated identified hazards.

Review the permit and validate the listed controls are in place

Okland

Subpart AA (3) pg 56

Atmospheric testing shall be conducted prior to any Okland employee entering any confined space.

OSHA

1926.1203(e)(2)(v)(A)