Air Sampling with Remote Control: Telematics for Personal Exposure Assessment
Modern sample pumps can send their operating status, current flow rate, and total volume sampled to a smartphone or tablet, giving safety and IH professionals confidence the samples are "delivered on time and intact."
- By Rob Brauch
- Oct 01, 2015
Exposure monitoring for hazardous gases, vapors, and particulates using personal air sampling pumps is the tried-and-true method for quantifying personal exposure and maintaining compliance with regulatory limits. Because many toxic and carcinogenic compounds still cannot be accurately measured with a wearable direct-reading instrument due to cross interferences or other environmental influences, laboratory analysis of a physically collected sample is necessary to comply with OSHA requirements using NIOSH-approved methods and satisfy multiple compliance directives.
Sample pumps present their own challenges for the safety and industrial hygiene professional, however, as they must be tightly controlled and their performance should be monitored regularly throughout the work shift if the proper sample collection procedure is followed. Failure to ensure the sample pump has maintained proper flow rate, has not "choked out" (as happens if a sample inlet tube has become blocked or kinked), or even stopped working completely due to lack of battery capacity or other problem, causes the sample to be challenged as invalid or insufficient for accurate exposure assessment. Add in the fact that most exposure studies involve multiple workers being tested on the same day, each going off to do different tasks in multiple locations, and you can see with many sample pumps running all at once, knowing the status of each individual pump becomes important—and this alone can be a time-consuming task. Failure to obtain a valid sample is even more disturbing because it means the worker being tested may have to wear the sample pump again the next day, which is something neither the worker nor the person responsible for sample collection wishes to endure.
Telematics is a term often used in the transportation industry to describe how information can be transmitted from over-the-road trucking fleets to a central location for logistics and control purposes. Information such as vehicle speed, mechanical condition, and even whether the vehicle has been incapacitated or otherwise immobilized will quickly become apparent to fleet managers who may be located hundreds or even thousands of miles away. Actions can then be taken to address the problem of any individual vehicle, making sure delivery objectives are met.
What do telematics have to do with air sampling? Using a more general definition of telematics, "the technology of sending, receiving and storing information via communications devices in conjunction with affecting control on remote objects" and by thinking of the multiple sample pumps being "wrangled" by the safety professional as a "fleet," the benefits of applying remote control and communications to air sampling devices becomes clear.
Sample pumps use various methods for collecting physical samples, but most common are filter cassettes for capturing dusts and particulates and sorbent tubes for collecting various chemical vapors and gases. For each material that can be sampled, there is a specific NIOSH method that defines how the sample pump should be set up, and the nominal flow rate and total volume of sample required for analysis are defined. When performing personal air sampling, it’s important to make sure the sampling pump is calibrated and set to the proper flow rate, which would typically be somewhere between 1.7 to 2.2 liters per minute if measuring for respirable dust using a cyclone to separate the ultrafine particles and collect them on a filter cassette. Or the flow rate may be set for a very low flow for using a sorbent tube to capture organic chemicals onto a charcoal tube for later analysis.
Modern pumps have "constant flow" regulators built in so they can maintain the set flow rate despite changes to the sample train impedance, or "backpressure." Backpressure increases as particulates buildup ("loading") occurs on a filter cassette, and to maintain a constant flow rate the pump must be able to sense the changing pressure as it builds and compensate by running the pump harder to maintain the same flow rate against the increased backpressure. This could compromise battery run times if the pump was not fully charged or has not been properly maintained, so a pump runs out of "juice" before enough sample volume has been collected. Other faults can occur, for example, when the tubing that connects the filter cassette to the pump body gets kinked or pinched, completely restricting air flow. Veteran "Pump Jockeys" are all too familiar with the many things that can go wrong when trying to collect a valid personal exposure sample using a sample pump. But so often, pumps are just one of the sampling devices being used on a given day—the safety professional or IH consultant may be visiting a remote operation for just a few days and will be tasked with collecting data on many hazards beyond dust, fumes, and vapors, likely including things such as noise dosimetry, heat stress monitoring, and risk assessment on their overcrowded task list.
It's here where the magic of telematics for air sampling come to the rescue. By utilizing wireless communications, modern sample pumps can send their operating status, current flow rate, and total volume sampled to a smartphone or tablet. Important running condition information such as remaining battery time and the number of times a pump has "choked out" and restarted can be viewed remotely. These data are key to understanding how the sample is proceeding and all can be viewed from a distance, without interrupting the worker or the work. As an added convenience, wireless-enabled pumps can be started and stopped remotely.
So with telematics, the ability to receive vital information about pump condition and status of the sampling session, plus control devices remotely, brings to the modern safety and health professional what vehicle fleet managers have enjoyed for years: peace of mind and confidence that the samples will be "delivered on time and intact."
This article originally appeared in the October 2015 issue of Occupational Health & Safety.