What is the minimum allowable percentage of oxygen required by OSHA in an excavation atmosphere?

The minimum allowable percentage of oxygen required by OSHA in an excavation atmosphere is 19.5%. This standard is established to protect workers from the dangers of oxygen deficiency, which can lead to serious health risks, including unconsciousness or death. An atmosphere with oxygen levels below 19.5% is considered hazardous and poses a significant risk for workers in confined or enclosed spaces.

This requirement reflects the need to maintain a safe work environment, ensuring that workers have enough oxygen to perform their duties effectively. Oxygen levels above 21% are typically found in normal atmospheric conditions, but OSHA's threshold of 19.5% specifically accounts for safety considerations in excavation work where air quality can fluctuate due to conditions such as soil disturbances or presence of gases and vapors.

The other percentages listed do not align with OSHA's safety standards for minimum oxygen levels in the workplace, reinforcing the importance of adhering to the established 19.5% requirement for ensuring worker safety in excavation atmospheres.