Short-term monitoring of formaldehyde: comparison of two direct-reading instruments to a laboratory-based method

Airborne formaldehyde concentrations can be measured using several different techniques, including laboratory-based methods and direct-reading instruments. Two commercially available direct-reading instruments, an RKI Instruments Model FP-30 and a PPM Technology Formaldemeter htV, were compared with National Institute for Occupational Safety and Health Method 2016 in different test environments to determine if these direct-reading instruments can provide comparable results. The methods yielded the following mean concentrations for 47 samples: NIOSH Method 2016, 0.37 ppm; FP-30, 0.29 ppm; and htV, 0.34 ppm. Results from both of the direct-reading instruments were correlated with the laboratory-based method (R² = 0.78 for FP-30, and 0.902 for htV). Comparison of the means of the three methods showed that on average the FP-30 instrument (p < 0.001) differed statistically from NIOSH Method 2016, whereas the htV (p = 0.15) was not statistically different from the NIOSH method. Sensitivity and specificity tests demonstrated that the FP-30 had sensitivity above 60% to detect formaldehyde concentrations at all the cutoff levels tested, whereas the htV appeared to have greater sensitivity above 88% for the levels evaluated.