Evaluation of a test method for measuring indoor air emissions from dry-process photocopiers

A large chamber test method for measuring indoor air emissions from office equipment was developed, evaluated, and revised based on the initial testin g of four dry-process photocopiers. Because all chambers may not necessaril y produce similar results (e.g., due to differences in sink effects, temper ature and humidity control, air exchange, pollutant monitoring, and measure ment biases), a preliminary four-laboratory evaluation of the revised test method was conducted. To minimize variability, the evaluation used a single dry-process photocopier that was shipped to each of the four laboratories along with supplies (i.e., toner and paper). The results of this preliminary four-laboratory evaluation demonstrate that the test method was used successfully in the different chambers to measure emissions from dry-process photocopiers. Differences in chamber design and construction appeared to have had minimal effect on the results for the vo latile organic compounds (VOCs). Perhaps more important than the chamber it self is the sample analysis as identified by duplicate samples that were an alyzed by a different laboratory. Percent relative standard deviation (%RSD ) was used to provide a simplistic view of interlaboratory precision for th is evaluation. Excluding problems with suspected analytical bias observed f rom one of the laboratories, the precision was excellent for the VOCs with RSDs of less than 10% in most cases. Less precision was observed among the laboratories for aldehydes/ketones (RSD of 23.2% for formaldehyde). The pre cision for ozone emission rates among three of the laboratories was excelle nt (RSD of 7.9%), but emission rates measured at the fourth laboratory were much higher.