During rain storming 2000 m water droplets falling down through 3000 m of ambient air from the

During rain storming 2000 µm water droplets falling down through 3000 m of ambient air from the top to the ground. In ambient air it containing 5 µm of particles with a density of 60 µg/cm3. Estimate the collection of particles. Assume Vt = 22 ft/s.