Rock Products

OCT 2014

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DUST MONITORING ROCK products • OCTOBER 2014 www.rockproducts.com 28 mation (logged respirable dust data and video) in a user‐friendly format. Helmet‐CAM is a simple and relatively inexpensive technology to set up and use. It consists of a lightweight video camera, an instantaneous dust monitor, and a method for housing these two in‐ struments in a way that allows miners to perform their work in a safe and unimpeded fashion. Once the video footage and dust data are obtained, the information is downloaded to a com‐ puter and the EVADE software is used to merge the video and dust data to‐ gether, permitting quick and effective assessment of the areas, tasks, and functions that impacted the miner's respirable dust exposure. Although there are a number of differ‐ ent types of commercially available cameras and dust monitors that can be used, we will only discuss the units used by Unimin and NIOSH during test‐ ing of this new technology. Helmet-CAM Components The first component necessary to employ the Helmet‐CAM system is a small com‐ pact video camera that records the worker's movements and tasks per‐ formed while wearing the system. The video unit chosen for NIOSH's testing was the POV (point of view) camera by V.I.O. This camera lens was attached to the miner's hardhat using various methods (flashlight clip, video camera mounting device, or duct tape). With the V.I.O. unit, a thin video cable approximately 18 in. in length connects the video lens to the dig‐ ital video recording portion of the device. The second component of the system is the instantaneous dust monitor. NIOSH chose the Thermo Scientific pDR‐1500 instantaneous monitor for the Helmet‐ CAM testing. Because this instrument was relatively new, NIOSH performed a comprehensive laboratory study at its Pittsburgh laboratory to ensure that the unit provided comparable dust data similar to what would be obtained with MSHA compliance and in‐house gravi‐ metric dust sampling [Reed et al. 2012]. The pDR‐1500 was also set to a 1.7‐lpm flow rate, which is the required flow rate as established by the American Conference of Governmental Industrial Hygienists (ACGIH) for the metal/non‐ metal industry [Mine Safety and Health Administration 1990]. The next component for a Helmet‐CAM assessment is a 10‐mm cyclone, placed on the miner's lapel. This location is classified as being within the miner's breathing zone and is identical to the location used for a gravimetric compli‐ ance‐type dust sample. A short length of conductive tubing is used to connect the cyclone to the main body of the pDR‐1500 monitor. The in‐ stantaneous dust monitor should be configured to take frequent samples for testing, which for the NIOSH testing was on a two‐second sampling interval. The last necessary item is some type of method to house the video camera and dust monitor to allow the miner to perform his or her work safely and with minimal interference. The au‐ thors recommend providing a number of different options to house the in‐ struments (backpack, safety belts, and safety vests) and allowing the wearer to choose the preferred method. Figure 1 shows a typical sampling setup using a backpack arrangement with the video camera lens on a miner's hardhat and the rest of the components housed either in or on the backpack. Helmet-CAM Usage One aspect critical to effective use of the Helmet‐CAM technology is that both the video camera and dust monitor need to be started at the exact same time because there is no adjustment within the EVADE software to synchronize the video and dust data. Once both units are simultaneously started, miners should be instructed to perform their routine job duties and tasks without any changes or deviations because they are wearing the device. The miner should also be provided with a time frame to wear the Helmet‐CAM sys‐ tem – usually recommended to be some‐ where between two and four hours to ensure comprehensive data collection. Once the miner returns the system after the pre‐arranged time period, the video and respirable dust exposure data files are downloaded to a computer. Using the EVADE Software Once the miner returns from perform‐ ing his or her work duties, both the dust monitor and video camera data are Figure 2 - The video taken by Helmet-CAM is in the top right corner and the respirable dust control graph appears along the bottom of the screen. Each blue dot on the graph represents a 2-second res- pirable dust measurement. This Helmet-CAM unit was inside the en- closed cab of a haul truck.

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