Recent advancements in sensor and wireless technology have created new and better ways to monitor short-term exposure limits (STEL) and long-term exposure limits (LTEL) for underground miners. Additionally, safety regulations in several countries are creating stricter and more robust requirements for monitoring environmental hazards and protecting underground workers from them.
This article will provide a brief overview of some high-level methods to advance your STEL and LTEL monitoring based on your mine’s broader technology infrastructure investment strategy.
The primary factors in evaluating the effectiveness of your exposure-limit monitoring strategy are accuracy of data collected and automation of measurements and alerts to reach real-time awareness.
The obvious way to track long-term exposure is to do periodic sampling of the environment and cross-reference with logs of workers' time spent underground. Depending on the mines processes this could be a manual endeavor. This approach is most commonly used to monitor against diesel particulate matter (DPM) in the Canada and US as well as coal dust in several countries.
The challenge with long-term exposure monitoring comes from combining data sources which may be prone to human errors. Ideally, some sort of worker tracking system is involved to provide an error-reduced record of who was underground and when. In order of accuracy these historical logs can be derived from shift-schedules, tag-in/tag-out logs or Real-Time Location Service (RLTS) logs.
Some products, such as the Smart Tagboard, can automatically log time spent underground for each individual worker and export it into common programs such as Excel. Once in Excel, it can be cross-referenced with environment sample logs to determine personalized long-term exposure metrics. This semi-automated system can work well for many small-to-mid sized mines that lack capital to invest in an underground RTLS system.
Many RFID-gate systems used for RTLS can also export historical records of time-spent underground. However, these systems often come with significantly higher investment costs which are comparable to the installation of a wireless network.
Fully-automated monitoring can be made possible by combining nearby environmental sensor data with worker location in real-time. This approach can be extremely effective at both STEL and LTEL monitoring.
For mines planning underground Wi-Fi network investments for short-interval control and better communication, the most cost effective approach is to use open-standard environmental sensors and a modern RTLS system.
Products such as ConnectedWorker™ Vizualization can then combine the two information sources into intuitive interfaces and to provide personalized STEL and LTEL alerts to underground operators, their supervisors, and safety managers.
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