What is the recommended MMAD (mass median aerodynamic diameter) range for the lower airways?

The recommended MMAD (mass median aerodynamic diameter) range for the lower airways is indeed between 2 to 5 micrometers (not nanometers as mentioned in the choices). This size range is effective for targeting the bronchi and bronchioles within the lungs. Particles within this diameter have the right balance of mass and aerodynamic properties to be inhaled deeply into the lower airways and deposited effectively.

Particles that are smaller than 2 micrometers may pass through the lower airways and be exhaled without being deposited, while larger particles above 5 micrometers tend to get trapped in the upper airways, not reaching the deeper regions of the lungs where they can have a therapeutic effect. Understanding this range is critical in respiratory care practice, as medication delivery devices (nebulizers, inhalers) are designed to ensure that particles within this MMAD range can be delivered effectively to treat conditions like asthma, COPD, and other respiratory ailments.