DID YOU KNOW?
Oxygen-deficient atmospheres are the leading cause of confined space deaths. [1]
KNOW THE RISK
- Oxygen-deficient atmospheres are a particularly dangerous hazard in confined spaces. Workers often don’t realize they’re in danger until it’s too late.
- A normal atmosphere contains 20.8%–21% oxygen. When oxygen levels fall below 19.5%, the atmosphere is considered oxygen-deficient. [1]
- These environments may be created when oxygen is displaced by other gases, consumed by chemical reactions, or absorbed by stored materials. [1]
- Low oxygen can cause dizziness, impaired judgment, unconsciousness, or death — sometimes without warning. [2]
MITIGATE THE RISK
1. Always Test Before Entry
- Test all confined spaces and high-risk areas with calibrated gas monitors before entering. Never assume air quality is safe. [1]
2. Know the Risk Areas
- Spaces to test include manholes, tanks, silos, pits, tunnels, and utility vaults. Many oxygen-deficient spaces look harmless from the outside. [1]
3. Check Other Areas With Potential for Gas Accumulation
- Oxygen may also be depleted near combustion engines, chemical storage, or welding operations. Always ventilate and test. [1]
ATMOSPHERIC SAFETY REMINDER
Lack of oxygen is a silent, invisible hazard. Testing, ventilation, and proper confined space entry procedures are critical to staying safe. Trust your monitor — not your senses.