Environ. Sci. Technol. 2008, 42, 4338–4343
Evaluation of Ultrafine Particle Emissions from Laser Printers Using Emission Test Chambers TOBIAS SCHRIPP,† MICHAEL WENSING,† E R I K U H D E , † T U N G A S A L T H A M M E R , * ,†,‡ CONGRONG HE,‡ AND LIDIA MORAWSKA† Fraunhofer Wilhelm-Klauditz-Institute (WKI), Material Analysis and Indoor Chemistry, Bienroder Weg 54 E, 38108, Braunschweig, Germany, and International Laboratory for Air Quality and Health, Queensland University of Technology (QUT), GPO Box 2434, Brisbane 4001, Australia
Received September 27, 2007. Revised manuscript received February 8, 2008. Accepted April 1, 2008.
It has now been recognized that some hardcopy devices emit ultrafine particles (dp < 100 nm) during their operation. As a consequence, the time-dependent characterization of particle release from laser printers is of high interest in order to evaluate the exposure of office workers to such emissions. The emission profiles of different printers can be compared in test chambers using a standardized test protocol and measuring devices with high time resolution. The extraction of meaningful and comparable data from the obtained data set is a complex procedure due to the different emission behavior patterns of the printers. The calculation of the unit specific emission rate (SERu) is of limited use because the emission profiles during the printing process ranged between short-term bursts and constant particle release. Therefore, other parameters such as the particle loss-rate coefficient, β, which provides information about the testing conditions, and the area below the time vs concentration curve, F, which characterizes the particle release, allow for a comparison of the different printer tests. Variations in the emission behavior could not be associated with specific manufacturers or product lines. In addition, when performing several print jobs on the same device, with only short pauses between jobs, the emission rate was reduced in some cases. This further complicates the ability to determinetheinfluenceofprinterconstructionandconsumables, such as toner and paper, on the concentration of particles emitted.
1. Introduction In our private and professional lives, personal computers (PCs) and their peripheral devices are now one of the most important objects of utility. Bako`-Biro` et al. (1) have already pointed out that such an extensive use of electronic equipment has caused major changes in office organization and work habits. However, computers also have an influence on the private life and leisure activities in residential dwellings. In recent years, PC units, monitor screens, and hardcopy devices, such as laser printers and photocopiers, have been suspected as a possible source of indoor air pollutants (2, 3). * Corresponding author phone: +49-531-2155-350; fax: +49-5312155-905; e-mail:
[email protected]. † Fraunhofer Wilhelm-Klauditz-Institute. ‡ International Laboratory for Air Quality and Health, Queensland University of Technology. 4338
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Several researchers have studied the release of volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) from PCs, CRT-monitors, and flatscreens (4). Ren et al. (5) reported a potential exposure to particle-phase polycyclic hydrocarbons (PAHs) from dust collected in computer housings, and a chamber study on emissions of VOCs, ozone, and PM10 from office equipment was performed by Lee et al. (6). Bako`-Biro` et al. (1) found that PCs had a negative impact on perceived air quality and performance of work in office buildings. On the basis of analogue measurements, Rockstroh et al. (7) proposed a standardized testing method for hardcopy devices. Airborne particles are currently the major focus of indoor air related research, especially since several studies have shown a significant association between particle concentration and health risks (8–11). In Germany, an extensive discussion is currently underway on the negative health effects caused by ozone, VOCs, and particles that are emitted from laser printers and photocopiers during operation, which was inspired when the German journal Umweltmedizin in Forschung und Praxis dedicated a special issue to the topic (Vol. 11, 2006 (5)). Within this issue, a comprehensive review of the literature by Gminski and Mersch-Sundermann (12), regarding possible health effects of laser printer emission, was published. In 2007 a publication by He et al. (13) describing ultrafine particle (UFP) measurements of different laser printers in real office environments also drew international attention on this topic. For precautionary reasons, the Federal Environmental Agency of Germany has created eco-labels for low-emitting products (14–16). However, in the case of particle emissions, the labels recommend the use of a gravimetric technique for the determination of the total suspended particles (TSP), which actually underestimates the influence of UFPs with an equivalent diameter
