Which two types of tests must be performed before entering a permit-required confined space?

The correct answer involves the testing for oxygen levels and flammable gases before entering a permit-required confined space.

In enclosed environments, the concentration of oxygen is critical because insufficient oxygen can lead to asphyxiation. To ensure a safe work environment, testing must confirm that oxygen levels are within the acceptable range—typically between 19.5% and 23.5% by volume—before personnel can enter.

Simultaneously, checking for flammable gases is essential as high concentrations can lead to explosive atmospheres. If flammable gases are present in concentrations above 10% of the lower explosive limit (LEL), it poses a serious risk to safety, making it imperative to conduct this test.

While temperature and humidity are relevant factors in other contexts, they do not directly impact immediate safety in the confines of a permit-required confined space in the same critical way as oxygen and flammable gas levels do. Thus, conducting these specific tests of oxygen and flammable gases is vital for ensuring the safety of workers entering such hazardous spaces.