Abstract
A field comparison between active and diffusive Hydrar samplers for measurements of mercury in air was performed in a chloralkali plant, in a thermometer factory, and in six dentistry surgeries. Personal and stationary air samples were taken, as well as blood and urine for biological monitoring. In the chloralkali plant, in the thermometer factory, and in dentistry, the diffusive samplers showed considerably lower values than the active samplers. In the range 1-123 μg/m3 of mercury in air, the passive samplers showed 64 percent (95 percent confidence interval 60-68) of the results of the active samplers. One possible explanation is that the proposed sampling rate given by the manufacturer was incorrect to use here, owing to the low air velocities. However, no model for correction of the sampling rate is available. Mercury levels in air were low in dentistry (median 2.8 μg/m3) and moderate in the thermometer factory (median 38 μg/m3). The exposure for maintenance workers in the chloralkali industry was higher, median 56 μg/m3 during normal maintenance and 97 μg/m3 during a shutdown. As expected, stationary samplings in industry showed lower concentrations than personal samplings. In dentistry surgeries, however, there was a relatively good agreement between the results from the personal Hydrar tubes and the stationary ones placed behind the patient, probably owing to the rather sedentary work in small rooms and the frequent use of evacuation during drilling operations.