Which type of hazard should always be checked before entering a confined space?

Atmospheric hazards are critical to check before entering a confined space because they can pose immediate and serious risks to the safety and health of individuals. Confined spaces may have limited air circulation, which can lead to oxygen deficiency or the accumulation of toxic gases, vapors, or fumes that can be harmful or even fatal if inhaled. This includes the presence of flammable gases that could lead to explosions. Monitoring for atmospheric hazards is essential to ensure that the environment is safe for entry and that proper safety measures, such as ventilation or personal protective equipment, are in place to mitigate these risks.

While physical barriers, temperature variations, and water accumulation are also important considerations for safety, they do not directly assess the life-threatening conditions that can arise from the atmosphere within confined spaces. These factors can lead to hazardous situations but checking atmospheric hazards is the highest priority when preparing for entry into a confined space.