Field Evaluation of a Diffusive Sampler for Monitoring Formaldehyde in Air: A Comparison of Methods

Abstract

This field study was conducted to evaluate the performance of the SKC Passive Bubbler (SKC Inc., Eighty Four, Pennsylvania) in monitoring formaldehyde in a working environment. For comparison, a traditional pump and impinger method, National Institute for Occupational Safety and Health (NIOSH) Method 3500, was used as the reference method. Two approaches were used for the field evaluation of diffusive samplers: paired comparisons, where individual samplers were matched to give a total of 22 data-pairs; and multiple comparisons, where sets of 5 passive monitors were compared to sets of 4 reference-method samplers in 6 sampling trials. Statistical analyses described in the NIOSH Protocol and the European Standard documents on diffusive sampler evaluation were used to determine a systematic difference between the two methods. An estimate of accuracy was also determined using the field precision and bias, which demonstrated that the SKC Passive Bubbler appeared to meet the Occupational Safety and Health Administration (OSHA) ±25% accuracy requirements for monitoring formaldehyde in the workplace. Of the comparative approaches used in this field study, multiple comparisons provided the most pertinent information, including field precision and a stronger statistical test for the comparison of the two sampling methods. Results from pooled, sampler pairs were not as statistically rigorous as were results from sampler replicates, due to variability between individual data-pairs.