Before entering a confined space, what is the first step required by CALOSHA?

Testing the confined space for oxygen deficiency is crucial because it directly addresses the primary safety concern when entering such environments. Confined spaces can have limited air circulation, making it possible for oxygen levels to drop below safe thresholds. Ensuring that there is a sufficient supply of oxygen is vital for the safety of individuals entering the space.

If oxygen levels are inadequate, it can lead to unconsciousness or even fatality quickly. Testing for oxygen deficiency must be the first step taken to ascertain whether the environment is safe for entry. This step is part of a broader safety protocol that includes identifying other hazardous conditions, but verifying oxygen content is critical because it can be immediately life-threatening.

The other options listed do not effectively address the immediate need for verifying a safe atmosphere before entry into a confined space. Checking for spiders or doing warm-up exercises does not significantly contribute to ensuring a safe working environment in confined spaces.