Emission Characteristics of Ultrafine Particles and Volatile Organic Compounds in a Commercial Printing Center

Laser printers are one of the common indoor equipment in schools, offices, and various other places. Laser printers have recently been identified as a potential source of indoor air pollution. This study examines the characteristics of ultrafine particles (UFPs, diameter <100 nm) and volatile organic compounds (VOCs) emitted from laser printers housed in a commercial printing center. The results indicated that apart from the printer type, the age of printers, and the number of pages printed, the characteristics of UFPs emitted from printers also depend on indoor ventilation conditions. It was found that at reduced ventilation rates of indoor air, there was a rise in the number concentration of UFPs in the printing center. Interestingly, the contribution of UFPs to the total number of submicrometer-sized particles was observed to be higher at a sampling point far away from the printer than the one in the immediate vicinity of the printer. Black carbon (BC) measurements showed a good correlation (r S = 0.82) with particles in the size range of 100–560 nm than those with diameters less than 100 nm (r S = 0.33 for 50–100 nm, and r S = −0.19 for 5.6–50 nm particles). Measurements of VOCs in the printing center showed high levels of m-, o-, and p-xylene, styrene, and ethylbenzenes during peak hours of printing. Although toluene was found in higher levels, its concentration decreased during peak hours compared to those during nonoperating hours of the printing center. IMPLICATIONS This study reports the emission of ultrafine particles (UFPs) and volatile organic compounds (VOCs) from laser printers in a commercial printing center. It was found that the number concentration of UFPs released was not only influenced by the printer-related parameters, but also by indoor ventilation conditions. The fraction of UFPs was high at lower air change rate and at distances away from printers, presumably due to the formation of new particles. The results imply that laser printers equipped with particle traps and high ventilation rates in the commercial printing center are needed to reduce the exposure of occupants to UFPs and thus the associated health risk.