An airstream at 1 atm and 27?C contains small spherical particles having a density of approximately 1000 kg/m3. The flow velocity of the airstream is about 0.9 m/s, and the mean velocity at a sampling device inserted in the airstream is about 0.75 m/s. The diameter of the spherical particles is about 16 μm. Calculate the error in the particle concentration as a result of the sampling process.