INSIGHT INTO CONTAMINANT MAPPING
Contaminant mapping is quite useful for communication of background concentrations to company decision makers as well as employees. Mapping activities can also document the effectiveness of engineering controls deployed throughout the environment to control exposures. It is also possible to use such mapping activities as a means to define the extents of regulatory areas (i.e. respiratory protection for respirable silica or hearing protection for noise).
Mapping typically involves the use of a real-time device to record concentrations at multiple locations within a facility. The results of these measurements are then placed (either numerically with tags, contoured into colormetric divisions, or both) onto a facility layout. Commonly mapped contaminants include respirable dust (particularly respirable crystalline silica), carbon monoxide, and noise.
Example Mapping Activity – ABC Company
Noise mapping is performed within the facility. In the example layout shown to the below, one-hundred and sixteen (116) noise levels were measured within the facility. Care was taken to target continuous background noise sources. Instances where short duration or mobile noise sources were observed (e.g. the audible alarm of the passing forklift, short duration hammering, the overhead public announcement system, etc.) were excluded. Often the linger time at each point is impacted by such short duration noise sources. Such sources should still be noted, as these activities are contributors to overall noise exposure. The background levels are often responsible for most of an employee’s dose, because the levels are present at all times.
It is ideal to further process the results of the initial survey into a contour map. These maps are easy to communicate to employees and upper management, and are ideal for posting within the workplace. They can identify sources of a contaminant, and in the case of dust and carbon monoxide, even determine air patterns and system balance.
Once sources have been identified, potential engineering controls can be deployed. In this fictional example, enclosures were placed around the highest identified noise sources (the motors). A follow-up map showed the effect of the engineering change, as half of the workplace that had earlier exceeded 80 dBA was now below that threshold, and the noise exceeding 85 dBA was mitigated from floor employees. The end result was that the majority of employees that exceeded 85 dBA over a full-shift was greatly reduced. Employees can now communicate more easily, the need for annual audiometric tests is reduced, and with further modifications (targeting the remaining contour in Production/Packaging), it may be possible to further reduce the noise levels within the facilities.
This contaminant mapping strategy can be deployed for many common indoor pollutants. Commonly targeted compounds include:
An example contour for respirable dust (targeting respirable crystalline silica) is shown to the right. This contour would be placed onto a transparent layer and overlaid onto a facility layout map. This greatly aids in determining sources and establishing a control program.
Insight IH Consulting has 13+ years experience in performing mapping activities at client sites. Typical jobs have ranged from a single map at a small manufacturing facility to 20+ contours in multiple runs across facilities exceeding one-million square feet. We utilize multiple programs (Excel, Surfer 8, AutoCAD) to create impactful contour maps that effectively communicate plant conditions.
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20 February 2019
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