Question

in october 2001 at the site of the world trade center in new york city, fires were still burning from the terrorist attacks that had brought down the buildings on september 11. what was the greatest danger for the respiratory systems of those people in the area?
multiple choice
large particles of airborne debris
falling material from damaged buildings
very small particles of airborne debris
the odor

Explanation:

Very small particles of airborne debris can be inhaled deeply into the lungs. The respiratory system has some defenses against larger particles (e.g., nasal hairs, mucus in the upper respiratory tract can trap larger particles). But very small particles (like fine dust from the debris) can bypass these initial defenses and reach the alveoli (tiny air - sacs in the lungs), causing significant respiratory problems. The odor is generally not a major threat to the respiratory system's structure and function compared to particulate matter. Falling material from damaged buildings is a physical threat (e.g., hitting a person) but not a direct threat to the respiratory system in the same way as inhaled particles.

Answer:

Very small particles of airborne debris