Field comparison of two analytical methods for NO2 and NO at an ammonium nitrate fertililzer manufacturing facility.
American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas. Fairfax, VA: American Industrial Hygiene Association, 1997 May; :85
The National Institute for Occupational Safety and Health (NIOSH) conducted an investigation at an ammonium nitrate fertilizer manufacturer as part of the Health Hazard Evaluation program. This facility produces approximately 260,000 tons of agricultural grade ammonium nitrate annually for distribution throughout the Midwest. One objective of the investigation was to determine potential employee exposures to oxides of nitrogen (NO2 and NO) in the acid plant using two NIOSH analytical methods. NIOSH Method 6014 utilizes a personal sampling pump with two triethanolamine (TEA) treated molecular sieve sorbent tubes in series, separated by a chromate oxidizer tube. NIOSH Method 6700 uses a passive dosimeter (Palmes tube) with TEA-treated screens. Two Palmes tubes are required to quantitate both NO2 and NO. One dosimeter directly measures NO2 concentrations while the other tube, with the addition of a chromic acid disc, measures total NO2 concentrations. The NO concentrations are determined by the difference obtained from the two dosimeters. Adjacent samples for NO2 and NO were collected using both methods at eight locations in the acid plant. NO2 concentrations ranged from 0.09 to 9.7 parts per million (ppm) using sorbent tubes and from 0.09 to 5.8 ppm using Palmes tubes. Airborne concentrations of NO ranged from 0.02 to 8.7 ppm and from 0.06 to 11 ppm using the sorbent and Palmes tubes, respectively. Using the Wilcoxoon matched pairs test, it was determined that the NO2 concentrations obtained from the two methods were statistically different (p=0.012), but the concentrations for NO were not statistically different (p=0.S44). The NO2 concentrations determined by the sorbent tube method were also statistically greater than the concentrations determined by the Palmes tube method. This observation contradicts previously reported results which indicated that the Palmes tube method gives higher results for NO2 than the sorbent tube method.
Ammonium-compounds; Nitrates; Fertilizers; Fertilizer-industry; Agriculture; Exposure-levels; Oxides; Nitrogen-compounds; Molecular-structure; Chromates; Sampling; Airborne-particles; Statistical-analysis
6484-52-2; 7727-37-9; 10102-43-9
American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas