Particles greater than what size (in micrometers) get trapped in the upper respiratory tract?

Particles greater than 10 micrometers in size tend to get trapped in the upper respiratory tract due to the anatomical structure and defense mechanisms of the respiratory system. The upper respiratory tract, which includes the nose, nasopharynx, and larynx, is designed to filter out larger particles through several means, including the turbulence of airflow and mucous secretions.

When inhaled, larger particles tend to collide with the surfaces of the upper respiratory tract due to their size, making it difficult for them to reach the lower respiratory passages such as the trachea and bronchi. This is particularly important because the upper respiratory tract acts as the first line of defense against pathogens and particulate matter, preventing them from entering the delicate tissues of the lungs where they could cause harm or infection.

Particles smaller than 10 micrometers can bypass this upper defense and reach deeper parts of the respiratory system, potentially leading to respiratory issues. Thus, the cutoff point of 10 micrometers is significant in understanding how the respiratory system protects itself from harmful substances.