By Christopher Wrenn, Senior Director, Sales & Marketing, Environics USA
This summer, a HazMat team was called to support a police investigation of a potential Clandestine Methamphetamine Lab (“Clan Lab”). A ChemPro100 set to the “Clan Lab” library was used as a sniffer for the entry into the single-family dwelling. Upon entry into the house, the ChemPro100 provided a “Chemical Detected” alert indicating that the entry team should use supplied air respiratory protection due to the potentially toxic atmosphere in the house. After entering the house, the atmosphere in it naturally cleared out the “Chemical Detected” alert stopped.
The kitchen was suspected to be the area where the “cook” of methamphetamine took place. But the kitchen had apparently been cleaned by the suspects prior to the team’s arrival. When the ChemPro100 approached the kitchen in the “Clan Lab” library, it again alerted with a “Chemical Detected” alarm. Toentify the location of the contamination, the technician using the detector stated “I switched over to the Trend [library] and saw the closer I got to the sink trap, the more the Trend went up. When I started to back away, the Trend would reduce.”
The HazMat Technician advised the agent in charge of the higher concentration found at the drain in the sink. Upon disassembling the sink trap and garbage disposal unit, they found small balls of what was suspected to be baking soda. It appeared that the suspect attempted to neutralize the toxic mix of clan lab chemicals using baking soda and then wash it down the drain to eliminate the evidence. However, the trap on the drain had accumulated the necessary evidence, which was sent for further laboratory analysis.
When first responders and investigators enter clan labs, they must be provided proper protection – which means wearing effective PPE (personal protective equipment) gear and carrying accurate and reliable detection devices and equipment. They also must be able to detect toxic gases and vapors, primarily to know not only when to “mask up” but also, and more importantly, when to exit the lab environment.
There currently are four principal gas-detection technologies available, and being used, that provide the type of protection needed by responders. However, although all of these technologies provide at least some protection, they fall short, in two important ways, of the full spectrum of capabilities really needed. More specifically, those technologies: (a) may not see the complete picture; and/or (b) provide the full protection needed to cope with all gas and vapor toxic threats at an incident scene. Fortunately, a relatively new multi-sensor “orthogonal” technology may be able to fill these gaps.
To understand why it is so important to remedy current deficients, one must recognize that there has been a dramatic increase in the past few years in the number and geographical diversity of clan labs producing methamphetamine and other illegal drugs. The chemical processing carried out at these labs is often done by untrained “cooks” who, rather than having an extensive chemical background, merely follow a simple “cookbook” of some type. The lack of chemical knowledge means that these cooks do not have a professional chemist’s respect for toxic and flammable chemicals – and the result, usually if not always, is widespread chemical contamination in and around most clan labs.
Initial Assessments & Carefully Calibrated Choices It is largely for that reason that responders and investigators of the crime scenes must protect themselves from the toxic and flammable gas and vapor threats left behind. Only after making an accurate assessment of the residual levels of gas/vapor/liquid and solids present can the responders and investigators properly protect themselves from these threats. Clan labs are crime scenes by definition, and investigators often have to make very quick decisions. Currently, the best way to assess on-scene risk is through use of a continuous monitor that provides instantaneous readings. The use of portable monitors not only decreases the risk to personnel, but also can reduce costs – primarily because the cost of medical testing for law-enforcement personnel who have been exposed to clan-lab chemicals in the wake of a major exposure can approach six figures.
There are four types of detection systems and equipment now commonly used to protect first responders and investigators in clan-lab environments: Wheatstone bridge/catalytic bead LEL (lower explosive limit) sensors, photoionization detectors (PIDs), electrochemical (EC) sensors, and colorimetric (“Draeger”) tubes.
Comparing the positives and negatives of each type will help responders understand what is being “seen” and what is in the “blind spot” of each technology. Following are brief descriptions of the four types of systems now being used by most of the nation’s law-enforcement agencies.
LEL Sensors: The most common continuously monitoring sensor used for these measurements by law-enforcement groups is the wheatstone-bridge/catalytic-bead/pellistor sensor (“wheatstone bridge”). The use of wheatstone-bridge sensors is problematic in the clan lab environment because: (a) They can measure flammable gases and vapors only – and some clan lab chemicals are not flammable; (b) They have difficulty nor only in measuring low vapor pressure but also the high-flashpoint chemicals often found in clan labs; (c) They do not possess the sensitivity needed for the ppm (parts per million) level of measurements usually required to determine toxicity threats; and (d) Many of the chemicals used in clan labs can permanently poison the wheatstone-bridge sensor, rendering it inoperable for making even gross decisions about combustible gas at LEL levels.
PID Sensors: A PID is a broadband sensor that can fill in some of the LEL gaps in measuring both chemical toxicity and 10 percent of LEL for clan lab investigators. The PIDs also provide a continuous means of measuring at the ppm levels needed for protection from the many toxic gases and vapors typically found in the clan lab environment. However, the most common PID lamp (10.6eV) misses some relatively common clan-lab chemicals – e.g., acetic acid, chloroform, hydrogen chloride – that have ionization potentials higher than the 10.6 eV lamp’s ceiling – higher-level eV lamps are available, but their high cost and extremely short life span generally rule out their use.
Another factor to consider is that a PID is a non-specific indicator that usually cannot differentiate the severity of threats and trigger an alarm appropriate to the threat(s) detected. The PID counts ions only; however, although ammonia and phosphine ions seem similar to the PID, those two chemicals possess very different human toxicities.
EC Sensors: EC sensors are generally specific sensors to particular species of gas. In a typical clan-lab scenario, it is common to see ammonia (NH3) and phosphine (PH3) sensors fielded as part of multi-sensor detection products. These EC sensors are reasonably specific and are sensitive enough to comply with time-weighted average (TWA) alarm limits. However, they have a limited life span (about one year or so), they are relatively expensive, and they require frequent calibrations (which involve the use of expensive and short-lived calibration gases).
Draeger Tubes: Colorimetric or “Draeger” tubes are commonly used in clan-lab responses and the investigations that follow. But they are neither continuous nor direct-reading. Therefore, although a wide variety of colorimetric tubes are available to detect the gases and vapors typically present in clan labs, an operator must firstentify the potential presence of a particular chemical, then take the additional time needed to run a tube test. However, if a chemical has not been detected at the beginning of an investigation, a Draeger tube is likely to miss it. On the other hand, if a chemical is vented during the investigation, and a tube is not used during that same period of time to detect it, the operator will miss that potentially toxic event as well. One of the principal benefits of continuous monitoring is that an operator does not have to stop to think about detection; it happens automatically, and provides continuing protection from any changes in the environment.
Chem-Pro100: An “Orthogonal” Solution One of the meanings of “orthogonal” is the characteristic of being independent (relative to something else). In the detection of gases, the term orthogonal is used to characterize detectors that use multiple, non-redundant sensors to solve a detection problem. Orthogonal detectors -- e.g., the Environics ChemPro100 – use aspirated IMS (ion mobility spectroscopy) sensors with additional sensors and what mathematicians call “fuzzy logic” to ify chemicals.
Orthogonal sensors have the desirable ability, particularly helpful in the clan-lab environment, to warn responders of the presence of more threatening chemicals than could be detected by any hand-held detection technology. The orthogonal detector represents a systematic approach to monitoring the clan-lab environment process for toxic gases and vapors; it also reduces both logistics costs and maintenance requirements, and has a much longer shelf life than the other technologies currently fielded.
While PIDs, LEL sensors, and specific EC sensors like ammonia and phosphine are routinely used during clan lab entries, none of these technologies can provide protection from as complete a list of clan lab chemicals as the ChemPro100. Other sensors have “blind spots” and can miss some important chemicals, while the ChemPro100 can see all of them. The ChemPro100 provides the most comprehensive protection from clan lab chemicals and provides the best masking alarm for entering potentially contaminated environments.
___________________________ Christopher Wrenn is the Sr. Director of Sales and Marketing for Environics USA, a provider of sophisticated gas & vapor detection solutions for the military, 1st responder and safety markets. Previously Mr. Wrenn was a key member of the RAE Systems team. Chris has been a featured speaker at more than 20 international conferences and has written numerous articles, papers and book chapters on gas detection in HazMat and industrial safety applications.