Calculate the mass of fine particles inhaled by an adult each year, assuming that he/she inhales about 350 L of air per hour and that the average PM index of this air is 10 g m3. Assuming that 2.5 each particle has a diameter of about 1 m, and that the density of the particles is about 0.5 g mL1, calculate the total surface area of this annual load of particles. [Hint: The surface area of a spherical particle is equal to 4r2, where r is its radius.]