According to OSHA standards, what is the maximum allowable percentage of the lower explosive limit of flammable gas in an excavation atmosphere?

The maximum allowable percentage of the lower explosive limit (LEL) of flammable gas in an excavation atmosphere, as per OSHA standards, is established to ensure worker safety by preventing the risk of explosions and harmful incidents. The correct choice reflects OSHA's guideline that workers should not be exposed to an atmosphere that exceeds 20% of the LEL.

This threshold is critical because concentrations of flammable gases reaching or exceeding this percentage increase the likelihood of a hazardous situation. By maintaining the limit at 20%, it allows for a buffer to account for potential fluctuations in gas levels and provides a safeguard against ignition sources, thereby protecting workers in the excavation area.

Understanding this standard is vital for those working in excavations, as it reinforces the importance of monitoring atmospheric conditions and implementing appropriate safety measures to mitigate the risks associated with flammable gases.