Prior to sampling, the collection substrates and back-up filter are preweighed and placed in the impactor. The sampling flow rate of the personal sampling pump is set at 2 LPM. The personal mounting bracket is attached to the lapel or pocket. After sampling, the impactor is disassembled and the substrates and filter weighed. If desired, the samples are analyzed chemically. The weight increase on each substrate is the mass of particles in the size range of that impactor stage. The total weight of particles on all stages and filter is added up, and the percent particle mass in each size range is calculated. Usually, the data is presented graphically as a cumulative size distribution showing the percent of particle mass smaller than the aerodynamic particle diameter. The respirable particle mass fraction is determined from the particle size distribution. The total particulate mass concentration also can be calculated since the impactor collects all particles.