Abstract
A formaldehyde (HCHO) generation system suitable for animal and human inhalation studies has been constructed and employed in a large scale human exposure chamber at the University of Maryland School of Medicine. The generation system employs modified industrial hygiene calibration manifolds to vaporize paraformaldehyde to form monomeric HCHO. Generated concentrations of HCHO were maintainable within ±5% of the target concentrations. Measurement of HCHO levels in the exposure chamber has demonstrated a close correlation (r2=.981) between the NIOSH chromotrophic acid technique and TGM-555 monitors over the range of 0.5 to 3.0 ppm, with the impinger-chromotrophic acid technique yielding an average of 95% of the TGM-555 measurements.