What happens to breathing at the highest point of the fire during the free-burning phase?

During the free-burning phase of a fire, the conditions can become extremely hazardous due to the intense heat and the presence of smoke and toxic gases. At the highest point of the fire, the temperature can significantly increase, leading to an environment where breathable air becomes severely compromised. In this situation, the heat can create a condition where inhaling air without mechanical assistance is nearly impossible. Instead, attempting to breathe in this environment can inflict severe damage to the throat and lungs, resulting in potential burns and respiratory failure. Therefore, the understanding of the dangers associated with high heat and smoke during a fire is crucial, highlighting the importance of using appropriate breathing apparatus in such situations.