When performing pre-entry atmosphere monitoring, the first thing monitored for should be

When performing pre-entry atmosphere monitoring in confined spaces, the first thing to monitor for is oxygen content. This is crucial because oxygen levels significantly impact human safety. Oxygen is essential for respiration; therefore, a deficiency or excess can lead to dangerous conditions for workers. If the oxygen concentration is below 19.5% or above 23.5%, it poses serious health risks, including asphyxiation in low-oxygen environments or the potential for fire and explosion in high-oxygen situations.

Prioritizing oxygen monitoring is essential because it sets the baseline for further assessments. If the oxygen levels are within safe limits, other factors such as flammable gases, toxic substances, and dust can be examined. However, without adequate oxygen, any work in the space becomes immediately hazardous, underscoring the necessity of checking it first. This proactive approach ensures personnel have safe breathing conditions before addressing other potential hazards.