Under what condition should employees not work in excavations?

Employees should not work in excavations when the oxygen levels are less than 19.5% or higher than 23.5%. This is critical because both low and high oxygen concentrations can lead to serious health risks, including loss of consciousness, impaired judgment, and ultimately death. An oxygen level below 19.5% indicates an oxygen-deficient atmosphere, which can lead to asphyxiation, while levels above 23.5% indicate an oxygen-enriched atmosphere that can increase the risk of fire or explosion.

Maintaining safe oxygen levels is a fundamental aspect of hazard recognition in confined spaces, such as excavations, and is crucial for ensuring the safety of workers in these environments. Monitoring air quality is a key safety practice mandated by OSHA standards to protect workers from these potentially deadly conditions.