What should firefighters assess regarding oxygen levels before entering a smoke-filled environment?

When entering a smoke-filled environment, assessing oxygen levels is crucial for firefighter safety. Oxygen deficiency risk is a primary concern because a concentration of less than 19.5% oxygen can significantly impair a firefighter's ability to function, leading to disorientation, unconsciousness, or even death. Firefighters rely on adequate oxygen levels to perform their duties effectively and to ensure their safety and the safety of others.

The potential for flashover, the status of fire containment, and current ventilation success are all important factors to consider, but they do not directly address the immediate life-threatening concern of oxygen deficiency. Ensuring that there is a sufficient level of oxygen is essential for survival and maintaining operational effectiveness during firefighting efforts. Therefore, understanding and assessing the risk of oxygen deficiency is vital before proceeding into an area where conditions may be hazardous.