Background  Printing and copying equipment is likely to release a large amount of particulate matter, thereby endangering human health. However, there is insufficient research on the level of particulate matter released by printers in offices and its influencing factors.

Objective  This study is designed to investigate the usage of printing equipment in college teachers' offices and the level of indoor particulate matter during printing, and to explore the influence of printer location and indoor ventilation on the particulate matter pollution level released during printer operation.

Methods  From 9:00 to 16:00 on January 4 to 6, 2021, 20 faculty offices in a university in Beijing were selected by convenient sampling to measure the indoor particulate matter level during printing, and to investigate the printing equipment usage of 31 users in the offices. Besides, experiments were designed to explore the influence of position and distance from a printer, ventilation, and the distance between a printer and a nearby window during ventilation on the number concentration of particulate matter released by the printers.

Results  Except one printer being placed on the ground, the other 30 printers were placed on office desks (0.71±0.16) m above the ground. Among them, 65% of the printers (n=20) were less than 1 m away from the users horizontally, and 74% of the users (n=23) accessed the printers 1-5 times a week, printing (7.03±4.07) pages per time. The peak mass concentrations in users' offices during printing of PM₁₀, PM_2.5, and PM₁ were (21.96±12.96), (7.92±5.54), and (5.77±5.00) μg·m⁻³, respectively, and the peak number concentration of PM_0.25−0.28 was (40941±36926) P·L⁻¹. The experiments showed that when the particle sizer was located in the front, side, and back of the printers, the peak values of PM_0.25−0.28 number concentration during printing were (24257±551), (12588±1354), and (11192±249) P·L⁻¹, respectively, and the difference among them was statistically significant (F=214.9, P<0.01); when the particle sizer was placed 0.1, 0.2, and 0.3 m away from the printers, the peak values of PM_0.25−0.28 number concentration during printing were (24257±551), (19847±1426), and (16480±878) P·L⁻¹, respectively, and the difference among them was statistically significant (F=44.66, P<0.01); when the experiment room was ventilated or not, the peak values of PM_0.25−0.28 number concentration during printing were (18595±488) and (24257±551) P·L⁻¹, respectively, and the difference between them was statistically significant (F=192.6, P<0.01); when the distance between the printer and the window was 1, 2, 3 m, the peak values of PM_0.25-0.28 number concentration during printing were (16780±823), (18347±348), and (18595±488) P·L⁻¹, respectively, and the difference among them was statistically significant (F=8.407, P<0.05).

Conclusion  The overall printer workload is small and the concentration of particulate matter in the faculty offices is low when the printers are working. Printer position, distance, ventilation, and the distance from a nearby window under ventilation conditions are factors affecting the concentration of particulate matter released by the printers.