Atmospheric monitoring is conducted prior to entry and additionally, as appropriate (continuous vs. periodic).

Checked for oxygen (19.5-22%), flammables (<10%), CO (<25PPM), & Hydrogen Sulfide (H2S) (< 10PPM)

Okland

Subpart AA (4) pg 56

Supervisors shall provide for all necessary equipment needed for Okland employees to safely enter a confined space (e.g. emergency rescue, ventilation, atmospheric testing, etc.).

OSHA

1910.146(d)(5)(i)