Hazardous Atmospheres

Excavations in landfills or near hazardous waste sites may expose employees to contaminated air or oxygen-deficient atmospheres (atmospheres containing less than 19.5 percent oxygen). In such worksites or any worksite where a hazardous atmosphere could reasonably be expected to exist, the atmospheres in excavations greater than 4 feet (1.22 m) in depth must be tested before employees enter.

Take the following specific precautions against hazardous atmospheres:

• Provide employees with proper respiratory protection or ventilation to prevent exposure to oxygen-deficient atmospheres and those containing a concentration of a flammable gas in excess of 20 percent of the lower flammable limit of the gas.
• When controls are used to reduce the level of atmospheric contaminants to acceptable levels, conduct testing as often as necessary to ensure that the atmosphere remains safe.

In addition to the requirements set forth here for personal protective equipment and atmospheric testing, employers are required to follow 29 CFR §1926.50-§1926.107 (Subpart D - Occupational Health and Environmental Controls, and Subpart E - Personal Protective and Life Saving Equipment).

To learn more about Trenching and Excavation visit our Trenching and Excavation Safety Online Training web page.