Particle emission from laser printers with different printing speeds

The present work investigated particle emissions for 10 min operating time for commercial color laser printers having different printing speeds (5, 24, 38 prints per minute (ppm)) in an experimental chamber (5 m3) under 1 h−1 of air exchange rate. Number and mass concentrations of the emission particles were measured, and a correlation between emission and printing speed is discussed. The average mobility equivalent particle diameter (50–244 nm) of the emission was proportional to the printing speed (5–38 ppm) but the average particle number concentration (5.3–1.2 × 104 particles cm−3) was inversely proportional to the speed. From morphology analyses of the particles, it could be estimated that the number decrease (or diameter increase) rates of the primary particles due to coagulation were 3.25 (0.17), 3.40 (0.44), and 9.31 × 103 (0.96) particles cm−3 s−1 (nm s−1) for 5, 24, and 38 ppm, respectively. Corresponding particle mass emission rates (or mass emission per print) were 0.007 (0.23), 0.039 (0.27), and 0.449 (1.97) mg h−1 (×10−4 mg print−1) for 5, 24, and 38 ppm, respectively.