What is the difference between PM10 and PM2.5?

What is the difference between PM10 and PM2.5?

• A. PM2.5 is inhalable; PM10 is respirable
• B. PM10 is inhalable; PM2.5 is respirable
• C. They are identical in size
• D. PM10 includes fine particles only

Answer: (B)

Particle size governs where in the respiratory tract a particle can travel. PM10 includes particles with aerodynamic diameter up to about 10 micrometers, which are generally inhalable—they can enter the nose and mouth and settle in the upper, larger airways. PM2.5 includes particles up to about 2.5 micrometers, which are small enough to penetrate deeper into the lungs and reach the lower airways and alveolar region, making them respirable. So the difference is that PM10 describes inhalable particles, while PM2.5 describes respirable particles. Remember, PM2.5 is a subset of PM10, since all PM2.5 particles are also PM10, but not all PM10 particles reach the deep lungs.

Particle size governs where in the respiratory tract a particle can travel. PM10 includes particles with aerodynamic diameter up to about 10 micrometers, which are generally inhalable—they can enter the nose and mouth and settle in the upper, larger airways. PM2.5 includes particles up to about 2.5 micrometers, which are small enough to penetrate deeper into the lungs and reach the lower airways and alveolar region, making them respirable. So the difference is that PM10 describes inhalable particles, while PM2.5 describes respirable particles. Remember, PM2.5 is a subset of PM10, since all PM2.5 particles are also PM10, but not all PM10 particles reach the deep lungs.