PM₂.₅ Emissions from Office Laser Printers: Real-Time Exposure Assessment and Risk Mitigation

Abstract

Laser printers are emerging sources of indoor air pollution, emitting fine particulate matter (PM₂.₅) and trace heavy metals. This study assessed exposure risks in 20 office environments using real-time PM₂.₅ monitoring and toner analysis. The PM₂.₅ levels were recorded with a TSI DustTrak DRX during work hours over two weeks. Toner types (OEM, compatible, remanufactured, drill-fill) were analyzed for Cu, Fe, Ni, Pb, and Cd via atomic absorption spectrophotometry. Risk assessments were based on U.S. EPA models. The PM₂.₅ concentrations ranged from 6.2 to 59.1 µg/m³ and correlated with print volume (r = 0.77). Lead and nickel were primary contributors to non-cancer (Hazard Quotient > 1) and cancer risks (up to 1.15 × 10⁻⁷). While metal levels in toner met regulatory limits, cumulative PM₂.₅ exposure raises concern. High-Efficiency Particulate Air (HEPA) filtration and use of low-metal toners reduced PM₂.₅ by 40% and lead exposure by 25%. Effective mitigation is essential in managing office air quality. Laser printers were identified as significant indoor sources of PM₂.₅ and trace metals, with risks strongly influenced by print volume and ventilation. Lead and nickel posed the greatest health concerns, while HEPA filtration and low-metal toners effectively reduced exposures.