Video display terminals and radon.
Recent reports indicate that video display terminals (VDTs) can collect radon progeny from the air. This occurs especially when they are turned off and may have negative electric fields which attract positively charged radioactive dust. We have studied this phenomenon in detail and evaluated various techniques for removing the gettered radioactivity while the video display terminal is both off and on. We have evaluated what happens when the video display terminal is switched, thereby reversing the electric field near the screen. We have also studied possible inhalation effects by a video display terminal operator during field reversal and find that although some radioactivity may be released during the cycle, room air currents redistribute it into the room with no detectable levels being inhaled by users.
Evaluation of the DC electrical environment in proximity to VDTs
Abstract Two VDTs were tested to determine their impact on the DC electrical environment. Characteristics of the DC environment were measured — ion concentration, ion current density and DC electric field. Measures of particulate levels, temperature and humidity were included since these factors are known to influence the DC environment. Ion concentrations, especially negative ion concentrations, varied as a function of distance from the VDTs, with the lowest values observed in the immediate vicinity of the VDTs for both models tested. This effect was slight and within the range of expected indoor values for ion concentrations. DC electric fields were generally found to be higher during VDT operation compared to controls, although they were within the same order of magnitude as commonly experienced fields due to charges on materials (e.g. clothing, carpet) indoors. Particulate levels were not observed to be altered by VDT operation.
SMART-I and Clever Counter Environmental Data Acquisition Systems
Many instruments measuring environmental pollutants such as SO2, NOx, etc., have an analog data output for strip-chart recording. Data analysis and retrieval is tedious. SMART-I and CLEVER COUNTER accept, data from these analog instruments and provide computer-compatible digital data storage. These microprocessor-based data logging instruments contain a time-of-year clock, six-decade counters, timers, and a serial communications interface. The CLEVER COUNTER consists of four counters, each with its own timer, while SMART-I consists of twelve counters, a common timer, and a computer-compatible magnetic recorder. The four channel unit stores SO2, NO, and NOx data, while the twelve channel unit handles the concurrent twelve channels of meteorological data at our regional monitoring site.