Airborne contamination monitoring

Airborne contamination. Monitoring should be carried out by means of continuous on-line measurement or by sampling and off-line analysis. Whenever there is a potential for a significant release of airborne contamination, monitors should be installed in the workplaces and/or the ventilation system. Sometimes area gamma monitors are used at locations of interest to warn of increasing airborne contamination. In this case, care should be taken to distinguish between dose rates from airborne contamination and those from other possible sources. 

Health Physics Laboratory. The health physics laboratory is located at the entrance to the radiation sources controlled area (Figure 2). From this laboratory the access to the radiation sources area is monitored and controlled. The health physics laboratory is equipped with portable beta, gamma, and neutron survey meters of various designs and ranges to facilitate the area monitoring, air monitors for airborne contamination, and anticontamination equipment. It is equipped with monitors and alarms for the area radiation detectors, pool water level indicators, and access doors. It also has ready access to the counting equipment of the radiochemistry laboratory. 

Questions about accuracy can also arise from the use of measurement data collected for one purpose that are used for another. For example, investigators and governments often rely on general area sampling of airborne contaminants from fixed monitoring stations in a metropolitan area as a proxy for exposures of individuals. However, numerous factors may affect the accuracy of this assumed relationship (e.g. the locations of the monitors, the mobility of the individuals with respect to the monitors over time, presence of other sources that affect the monitors but not the individuals, exposures of the individual in the workplace or elsewhere that are not picked up by the area monitors). 

The personnel working in the corrosion laboratory are usually exposed to a variety of chemicals and gases. The monitoring of airborne contaminants is to ensure that potential employee exposures are controlled. It is also useful to monitor chemical exposure of personnel and to compare the levels with chemical exposure guidelines of National Institute for Occupational Safety and Health (NIOSH), Occupational Safety and Health Administration (OSHA) OSHA (29 CFR 910.1450, 29 CFR 1910.1048, 11910.1001-1101, Z9 CFR 1910, subpart Z and National Health Canada). It is also useful to perform a walkthrough check for hazardous chemicals and exposure of personnel to the chemicals, as shown in Figure 3.2. 

Hiac/Royco is a division of Pacific Scientific together with Met One. Hiac manufacture a wide range of counters for liquid borne systems whereas Royco and Met One manufacture counters to monitor airborne contamination. A brief description of a selection from the Hiac range is presented below. 

Two types of sampling monitors are in general use air samples are used to assess the airborne contamination levels at selected points. In the case of particulate materials a volume of air is drawn through a filter paper on which the particulates are deposited. An alarm may be set on increase of activity. 

A third study evaluated S04 and exposure to 24 children (ages were not provided) living in Uniontown, Pennsylvania (Suh et al. 1992). This study did not focus on ammonia exposure per se, but on other airborne contaminant concentrations in aerosols found outdoors, indoors, and by personal monitors. It sought to determine how personal exposures to these aerosols correlated with indoor and outdoor concentrations. Ammonia concentrations were measured in order to assess their potential for neutralizing found in aerosols. Ammonia was found to be in highest concentrations near the children (detected by the personal monitors), followed by indoor concentrations, and were minimal outdoors. It was proposed that a large proportion of the found in indoor aerosols are neutralized by NH3, and thus would lower the children s exposure to acid aerosols. The authors noted that more research is needed to fully model the influence of factors, including NH3, on indoor acid aerosol exposure. 

If surfaCe-to urface contamination is potentially more significant than airborne contamination, as many aseptic filling operators now believe, then touch plates (finger dabs) become a critical part of environmental monitoring. Not so much does their value lie in whether they indicate contamination or absence of contamination but in the identification of contaminants to their most likely source. Touch plates should be seen as a route to identifying systems failure and... 

Reimann C, Banks D, de Caritat P (2000) Impacts of airborne contamination on regional soil and water quality the Kola Peninsula, Russia. Environ Sci Technol 34 2727-2732 Riget F, Asmund G, Aastrup P (2000) The use of lichen (jCetraria nivalis) and moss (Rhacomitrium languginosum) as monitors for atmospheric deposition in Greenland. Sci Total Environ 245 137-148... 

The process of measuring an individual s exposure to airborne contamination in the workplace. A sampling device is fitted to suspected individuals who may he exposed. Personal sampling devices include gas monitoring badges, impingers, and filtration devices. 

The need for accuracy in a workplace monitoring method is vital, since the measurements need to reflect the actual conditions in the workplace. On the other hand, given the temporal and spatial variability in most airborne contaminant concentrations in the workplace, it is generally not required that the monitoring method be highly accurate, i.e. within a few percent of the true value . The NIOSH (USA) recommends that (1) the overall bias of a monitoring method be < 10% of the values determined by a well-characterized independent method, and (2) that the overall precision of sampling and analysis should be such that the total error is <25% in at least 95% of the samples analyzed, based on the analysis of 6-10 samples at each of three or four concentration levels. 

Diesel exhaust is a dangerous airborne contaminant. Currently available control technology could significantly limit many diesel exhaust exposures, although additional information and research is needed on the methods to monitor diesel particulates, and determine the level of risk such particulates cause. OSHA is developing an action plan to reduce worker exposures to this hazard but is not initiating rulemaking at this time. 

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