Which statement is true about PM10 and PM2.5 in indoor air?

• A. They are the two particle sizes mentioned that make up a large portion of indoor dust capable of reaching the lungs.
• B. They are the same as PM1 particles.
• C. They are not relevant to indoor air quality.
• D. They are larger than 10 micrometers.

Answer: (A)

Particles size determines how deeply they can travel in the lungs. PM10 and PM2.5 refer to particles with aerodynamic diameters less than 10 micrometers and 2.5 micrometers, respectively. These smaller particles are common in indoor environments and make up a large portion of indoor dust that can be inhaled and reach the lungs, with PM2.5 capable of penetrating the deepest parts of the respiratory system. That’s why this statement is true: PM10 and PM2.5 are the two sizes most commonly cited for indoor dust that can reach the lungs. They are not the same as PM1, they are relevant to indoor air quality, and they are not larger than 10 micrometers (PM10 is up to 10 μm, PM2.5 up to 2.5 μm).