What size particles can reach the lowest parts of the lungs?

Particles that are 3 microns in size can penetrate deep into the respiratory system, reaching the bronchioles and even the alveoli of the lungs. The reason for this is primarily due to the way the respiratory tract can filter particles. Larger particles tend to get trapped in the upper airways or the trachea because of mechanisms like inertial impaction, sedimentation, and interception. Particles around 10 microns and larger are typically filtered out by the nose or upper respiratory tract.

Particles in the range of 2.5 microns and smaller are classified as PM2.5 and are particularly concerning for health as they can bypass the natural defense mechanisms of the respiratory tract and deposit deep within the lungs. This can lead to various health issues, such as respiratory diseases and cardiovascular problems, as these small particles can enter the bloodstream.

Understanding this concept is crucial for environmental health specialists, as they assess air quality and its impacts on public health. Knowledge of particulate size and their potential to affect human health is a pivotal component in evaluating risks associated with air pollution.