Which of the following statements about mezzanines is true?

The statement regarding untenable smoke concentrations affecting the mezzanine level before impacting the floor below is true. This relates to how smoke behaves in a fire and how it accumulates in different spaces. When a fire occurs, smoke rises due to its temperature and buoyancy; however, as it rises, the distribution and concentration can be uneven. This means that smoke could potentially accumulate at the mezzanine level first before affecting the main floor below, particularly in spaces with high ceilings or open layouts.

Understanding the dynamics of smoke movement is crucial in life safety planning, especially in buildings with mezzanines, as this can influence evacuation strategies and the effectiveness of smoke control systems. Recognizing that mezzanines are often open to the space below contributes to a clear comprehension of the risks involved, especially in emergency situations.