Since the National Institute for Occupational Safety and Health (NIOSH) and Unimin Corp. developed the Helmet-CAM assessment technology, which integrates video and dust data into an exposure assessment tool, it has proven to be so effective for assessing respirable dust exposure that it is now being expanded and applied to other health contaminants, including noise exposure. Recently, NIOSH partnered with Vulcan Materials Co. to be the first to test and evaluate the Helmet-CAM system for noise assessment at its Havre De Grace mining operation near Baltimore, Md. Kelly Bailey, Vulcan’s corporate director of Safety, Health, and Environment, along with a team of individuals from his Industrial Hygiene staff, traveled to the Havre De Grace Operation to learn about the Helmet-CAM assessment system and to participate in this testing. Nine different Vulcan Material Co. miners wore the Helmet-CAM system for approximately a 2-hour time period.
Figure 1. This beta version of EVADE (version 2.0) software shows graphs representing both the miner’s noise exposure (1-second noise measurements plotted as a function of time) and respirable dust exposure. In the upper right of the figure above the graphs, the activity being performed is viewed.
The system included a video camera attached to the worker’s hardhat, as well as a dosimeter and a respirable dust monitor for a combined noise and dust assessment to be made simultaneously. The launch of this new health contaminant assessment was extremely positive for Vulcan’s corporate health and safety staff, for the plant’s management team, for the miners who actually wore the Helmet-CAM system, as well as for NIOSH personnel involved in this testing. NIOSH is currently in the final stages of modifying the related software (EVADE v2.0) to allow the Helmet-CAM technology to be used with other types of health assessments, and this approved version should be ready for public release within the next few months.
Developing the Helmet-CAM
The Helmet-CAM assessment technology system breaks a major roadblock preventing the assessment of how, when, and where workers are being exposed to respirable silica dust. Respirable silica dust and the development of silicosis remains a serious health issue for all workers around the world. A significant challenge in the fight against silicosis has remained the inability to determine the magnitude of respirable silica exposures in the workplace. This challenge has been reduced significantly by the development of the Helmet-CAM technology, which provides a quick and proven method to identify elevated levels of worker exposure, and a simple assessment tool to determine the effectiveness of targeted engineering control techniques or interventions to lower respirable dust exposures.
Figure 3. Various Vulcan miners wear the Helmet-CAM system for simultaneous noise and dust assessment as they perform their regular duties.
Helmet-CAM is a simple and relatively inexpensive technology to set up and use. It consists of a lightweight video camera, a direct-reading data-logging aerosol monitor, and a method for housing these instruments in a way that allows workers to perform their work in a safe and unimpeded fashion. A small compact video camera is attached to a worker’s hardhat and records the workers’ job tasks and movements while wearing the system. Simultaneously, an instantaneous aerosol nephelometer quantifies the worker’s respirable dust exposure at specific time intervals — typically 2-second intervals. Once the video footage and respirable dust data are downloaded to a computer, the EVADE (Enhanced Video Analysis of Dust Exposure) software merges the data for simultaneous viewing to provide an assessment of specific aspects that impacted the workers’ respirable dust exposure. By identifying those culprits responsible for elevated respirable dust exposure, a hierarchy of controls can be tailored and implemented to lower exposures.
After extensive field testing by NIOSH at numerous mine sites in many different states, Helmet-CAM has become a driving impetus for mine operators to implement engineering control technologies and interventions to lower respirable dust exposures. Numerous examples can be cited by major stakeholders as to the benefits of identifying elevated respirable dust exposures which, in turn, results in the implementation of engineering controls/interventions to successfully lower worker’s exposure. Accordingly, this technology has been adopted by many of the member companies in the Industrial Minerals Association–North America and the National Industrial Sand Association. Helmet-CAM has also been adopted as a training tool for a number of major industrial sand producers. For example, plant management at one company included the Helmet-CAM as part of its management performance appraisal requirements, making the use of this technology mandatory for assessing workers’ exposures. The Helmet-CAM assessment technology is being used extensively throughout the United States in the mining industry and at various locations around the world, including Canada, Mexico, South America, Europe, Asia, and Australia.
Assessing noise exposure
Figure 2. A dosimeter microphone is attached to miner’s right shoulder harness, while a10-mm cyclone to classify respirable dust is attached to the left harness.
Assessment of sound levels in various working areas is important to determine the tasks that are contributing to the noise exposure of individual workers. There is no visual indicator to workers that they are in an area with hazardous noise levels, so they are often unaware of the potential danger. Importantly, dosimeter data alone does not indicate the cause of noise exposure — just the times that the exposure was acquired. Therefore, dosimetry measurements must be done along with an observer completing a time-motion study of the worker. The time-motion study involves following the worker through his or her various tasks and documenting those tasks in accordance with the time. Then, the tasks are aligned with the dosimeter measurements based on time, to determine where the most hazardous noise levels were generated. This is time-intensive for the observer, and may cause the worker to alter his or her normal activities. Thus, the data obtained may not be representative of the worker’s actual daily activities.
With the Helmet-CAM, the need for time-motion study is eliminated. The video, when synchronized with the dosimeter data, allows for determining the specific tasks that led to the most noise exposure. The observer can view the individual tasks the worker was performing throughout the day, as well as locations where he or she was working while simultaneously viewing the sound levels associated with those tasks and locations. This can remove much of the potential for error in note-taking or task observation. An additional benefit of using the Helmet-CAM is how easy it is for workers to view and review the noise exposure information through the EVADE program and understand what they are seeing. This can be a useful training exercise — workers can see their activities and understand exactly how those activities contributed to their overall noise exposure. This level of training and worker involvement is not possible with standard dosimetry and time-motion study.
Simultaneous noise and dust testing
Based on the success of Helmet-CAM for the identification and control of respirable silica dust, the natural progression is to then expand this technology for assessment of other related health effects, such as noise exposure, which can be done simultaneously (see Figure 1). Through a long-standing and positive working relationship between Vulcan Material Co.’s Kelly Bailey and NIOSH, noise assessment testing was performed during the last week of September 2014 at one of Vulcan’s mining operations.
To perform this testing, a team of researchers from NIOSH’s Office of Mine Safety and Health Research (OMSHR) facility in Pittsburgh, Pa., traveled to Vulcan’s Havre De Grace Facility near Baltimore, Md. These researchers met with Bailey and a team of his health and safety staff, along with key plant management team members, to explain the Helmet-CAM assessment technology and to lay out a proposed test plan. The following morning, Helmet-CAM assessment testing was initiated for both noise and respirable dust.
To begin the process, the mine’s management team requested that three different miners come into the mine’s conference room to be set up with the Helmet-CAM technology. When the miners arrived and were ready to be fitted with the system, the first component was to attach a small compact video camera to the miner’s hardhat. This camera was used to record the worker’s location and the tasks and functions being performed over the time while wearing the system. NIOSH chose to use a V.I.O. POV camera, but there are many different types of commercially available compact video cameras available (GoPro, Contour, Fire Cam, Polaroid XS100i, and others) that can be used with the Helmet-CAM technology. The V.I.O. system employs a video lens that was attached to the miner’s hardhat using a commercially available flashlight clip and duct tape. A thin cable, approximately 18 inches in length, connects the video lens to the digital video recording portion of the device. This video device creates two digital video files with “avi” and “thm” extensions, which are used by the EVADE software program.
The second component of the Helmet-CAM system is the assessment component, which, in this case, was to monitor for both noise and respirable dust simultaneously. For noise exposure assessment, NIOSH chose to use the Larson Davis Spark noise dosimeter. Noise dosimeter data can be used to determine sound levels at any point in time or to determine noise exposure over a specific period of time. The dosimeter was set up to continuously record A-weighted sound levels at 1-second intervals. The 1-second samples could then be compiled over any time period of interest to evaluate exposure. Prior to the start of the shift, the dosimeter microphone was attached to the midpoint of the worker’s left shoulder. After the predetermined work time period had ended, the dosimeter was removed from the worker, and the noise data was downloaded and analyzed to determine the amount of noise exposure the worker encountered. Exposure calculations derived from the dosimeter data were based on the MSHA permissible exposure level (PEL) of an 8-hour time-weighted average (TWA) sound level of 90 dB(A) with a threshold of 90 dB(A) and a 5-dB exchange rate.
For respirable dust assessment, the Thermo Scientific pDR-1500 instantaneous monitor was used. Initially, NIOSH performed a comprehensive laboratory study with this light-scattering nephelometer to ensure that the unit provided comparable dust data to what would be obtained with MSHA compliance and in-house gravimetric dust sampling. The unit was slightly modified so that a 3-foot section of conductive tubing could be used to connect to the 10-mm Dorr-Oliver cyclone, which is the typical pre-classifier device used for respirable dust sampling in the metal/non-metal mining industry. The pDR-1500 was also set to a 1.7-liter/minute 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. For testing, the 10-mm cyclone was placed on the miner’s lapel, within the miner’s breathing zone and similar to the method used for a compliance-type dust sample. A 3-foot length of conductive tubing was used to connect the 10-mm cyclone to the main body of the pDR-1500 monitor. The instrument was configured to integrate samples over a 2-second period for this testing.
The last item necessary for the Helmet-CAM system was a method to house the video camera, as well as the noise and dust instruments, in a way that would allow the miner to perform his or her work in an un-impeded fashion and with minimal interference. For this testing, the best approach was to provide a lightweight backpack with a number of pockets to house the camera’s logger unit and the noise and dust monitor (this approach emerged as the method preferred by miners in all of NIOSH’s previous testing). An advantage of using the backpack is that it has two shoulder harnesses, as well as two other straps — one at chest level and the second at the waist — which allows the backpack to be securely adjusted and tightened to the wearer’s needs. The other benefit with the two shoulder harnesses is that the microphone for the dosimeter was attached to one shoulder harness, and the 10-mm Dorr-Oliver respirable dust classifier was attached to the other (Figure 2). Duct tape was then used to secure all the cables in order to provide a significant level of safety to the worker to minimize the possibility of them being caught or tangled on anything while performing their work.
The video camera lens was attached to the worker’s hardhat using a holder for a small flashlight clip. The video unit was turned on, and the lens was adjusted to ensure that it was recording in a horizontally aligned manner. The aligned camera lens was also duct-taped in place to ensure that it did not move over time and lose its alignment as workers performed their job tasks. At this point, the video camera, dosimeter, and dust monitors were all started simultaneously. It was critical that all three units were started at the same time, because there is no current adjustment in the EVADE software to offset the start time.
The miners were asked to return to work and to wear the Helmet-CAM system for a pre-determined time frame (Figure 3). The miners were instructed to perform their routine duties and tasks without any changes or deviations in relation to their wearing of the device. For all testing, the video sound function was deactivated because it was not needed.
After approximately two hours, the miners returned to the mine’s conference room, and the video camera footage was downloaded to a laptop computer. Because numerous workers were to be evaluated at the same site, it was important to differentiate the numerous videos, dosimeter data, and dust data files taken at this operation. All files were provided a name assigned by Vulcan that could be used to distinguish between the different miners. When using the EVADE software, this same naming system was used to ensure that the correct video files, dust data files, and dosimeter data files were linked together in the analysis software program.
Next steps
With the Helmet-CAM technology being successfully used in the United States and internationally to identify and control respirable silica dust exposures, the intent is to now expand this technology so that it can assess any type of physical, chemical, or biological agent where an instantaneous monitoring device is used — such as monitoring of diesel particulate matter, chemical, and noise exposure levels.
In a recent cooperative study between Vulcan Materials Co. and NIOSH, the Helmet-CAM technology was shown to successfully be able to simultaneously monitor and provide assessment for both noise and respirable dust exposures to miners. Further, the EVADE software that complements the Helmet-CAM technology is currently being expanded (version 2.0) to allow multiple video files and contaminant data to be viewed simultaneously.
The software for assessing worker’s respirable dust exposure to respirable dust (EVADE version 1.0) for the Helmet-CAM technology is currently available at the NIOSH Mining website at www.cdc.gov/niosh/mining/Works/coversheet1867.html. Within the next few months EVADE version 2.O will also be available at this website.
Disclaimer
Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.
Andrew Cecala, lead mining engineer, and Amanda Azman, research audiologist, are both researchers with the NIOSH Office of Mine Safety and Health Research in Pittsburgh, Pa. Kelly Bailey is the corporate director of safety, health, and environmental services for Vulcan Materials Co.