Which of the following is an indicator of heat stress that might affect a firefighter's performance?

Pallor, characterized by paleness of the skin, is an important indicator of heat stress that can affect a firefighter's performance. It suggests that the body is experiencing difficulties in regulating temperature and blood flow, often indicating that the person is in a state of distress, potentially due to overheating. During strenuous activities, especially in high-temperature environments, blood flow is redirected to the skin in an effort to cool the body, and pallor can indicate a failure in this process, leading to compromised performance.

Recognizing pallor as a symptom allows for timely intervention to prevent more severe heat-related illnesses, which are critical in ensuring that firefighters maintain their performance and safety on the job.