The answer would be a chemical hazard
It depends on the context; it does allow gas exchange to occur, however gas exchange occurs in the capillaries of the alveoli.
Note:
<em>The upper airway not only provides a passage for air to be breathed in and out of the lungs, but it also heats, humidifies and filters the air and is involved in cough, swallowing and speech. Air goes to the lungs where gas exchange will occur. </em>
If you are still confused try looking up gas exchange diagrams for more information.
TLDR: Disagree; it does allow oxygen to flow into the lungs as the upper respiratory tract is a passageway to the lungs. However, the upper respiratory tract is NOT where gas exchange occurs because the lower respiratory tract holds the lungs which allow for gas exchange.
