Which pollutant can penetrate the lungs' natural defenses?

Question

Quizplus · Accepted Answer

Fine and ultrafine suspended particles, such as particulate matter smaller than 2.5 microns, can penetrate deep into the lungs and bypass the body's natural defenses, such as the mucous membranes and cilia. This can lead to respiratory irritation, inflammation, and other health effects. Ozone and other pollutants can also cause respiratory issues, but fine and ultrafine particles are particularly harmful due to their ability to penetrate the lungs. Large suspended particles and acid rain are generally less harmful to human health.

Which Pollutant Can Penetrate the Lungs' Natural Defenses