Detection and Monitoring PDF

Detection and Monitoring - This helps provide additional or confirming information so that emergency responders can employ the safest approach in a risk-based response to a product release. - Monitoring must be an ongoing process. - No single instrument will completely identify or qua...

Detection and Monitoring - This helps provide additional or confirming information so that emergency responders can employ the safest approach in a risk-based response to a product release. - Monitoring must be an ongoing process. - No single instrument will completely identify or quantify the compounds that are identified. - Equipment can help: o Estimate the concentrations of a known product. o Help identify unknown products. o Identify hazards. o Assist in evaluating the health and safety eEects of a chemical. o Evaluate exposures during medical surveillance. Fundamentals of Monitoring - Often designed with specific features that make them safe and user-friendly in the field. - Features to consider when evaluating detection and monitoring. o Portability and durability o Cost § Maintenance cost § Calibration cost § Sensor replacement § Updates § Training o Ease of operation § While wearing PPE o Usability in a hazardous environment § Explosion-proof § Intrinsically safe § Purged - All certified devices must be marked to show class, division, and group. - Technology o Must be able to read, interpret, and communicate data from the detection and monitoring equipment used at a hazardous materials incident. o These factors include: § Instrument response time The time it takes to generate a data. It may range from seconds to minutes. The response relies on: o Test to be performed. o Wait time between sample periods. o Sensitivity of the instrument. § Interference Some equipment may be subject to some type of interference, which may impair the credibility of the equipment. § Sensitivity Accuracy of the measurement of changes in concentration Detection limit o The smallest quantity of a material that is identified within a stated confidence level. Saturation limit o The concentration at which the addition of more solute does not increase the levels of dissolved solute. § Selectivity  The ability of an instrument to detect and measure a specific chemical or group of similar chemicals. It depends upon interfering compounds that may produce a similar response. Interference can aEect the accuracy of the instrument reading. § Specificity A comparison of the relationship between an antigen and antibody. § Operating range Accurate concentration measure by the instrument § Amplification The ability to increase small electronic signals emitting from the detector to the readout Does not change the sensitivity. § Accuracy Relationship between an actual value and the instrument reading § Reliability The ability of a device to provide consistently accurate readings. - Instrument Response o The elapsed time between the movement (drawing in) of an air sample into a monitoring/detection device and the reading (analysis) provided to the user. o Times depend on: § Type of test to be performed. § Dead time is required for the instrument to analyze and display the data. § Sensitivity of the instrument o Some instruments may be passive, relying on air movements and currents to obtain the sample. o Some instruments may utilize a pump and draw tube to obtain the sample. Calibration - The operation to standardize or adjust a measuring instrument. - Checked before and after each use and in intervals. - Checked against the required calibration gas. - Bump Test (Calibration Test) o The set of operations ensures that an instrument’s alerts work at the recommended test levels of hazard detection. o Compared to the actual quantity of gas present. o Performed immediately before entering the hazard area. o It is not intended to reset the calibration but to determine the correct setting in the existing calibration. - Relative Response/Correction Factors o Each instrument responds to a vapor or gas as if detecting its calibration gas. Although the instrument will give a reading, the data presented may be higher or lower than the actual concentration. o Correction factors or relative response curves can convert the instrument reading to the true concentration of the vapor or gas present. However, they will only work if the vapor or gas can be identified. - Cross-Sensitivities and Interference o Interferences can result in either decreased instrument sensitivity or false readings. o Cross-sensitivities may occur in many diEerent types of instrumentation. o Filters may be available to prevent this Action Levels - Defined as a response to known or unknown chemicals or products that will trigger some action. - When the Action level is reached, it may trigger:  o Removal of unprotected or unnecessary personnel o Additional Monitoring o Alteration or adjustment of PPE o Total area evacuation o When considering action levels for LEL, it must be determined if the product is known or unknown. § If the product is known, then it may be possible to have high LEL action levels. § If the product is unknown, technicians must take a more conservative approach. o There may be multiple action levels established for response. o As readings change, technicians must reassess the situation and take action based on the new findings. Individual Monitoring and Area Monitoring - Two main methods of sampling to determine exposure to chemical hazards: individual monitoring and area monitoring. - Individual monitoring is when the emergency responder carries an instrument to evaluate the work area. - Area monitoring is performed by a team, sampling the area in an organized manner. - Individual Monitoring o Conducted with handheld equipment o Various factors must be considered when using this method because they can influence the technician's results and safety. o Factors to consider: § Location of the area to be monitored. § The proximity of the product within the area. § Oxygen concentrations within the sample area. § The specific instrument responds to a given substance. o Utilize a risk-based response. o Monitoring locations should be chosen based on environmental conditions and any information that may be known about the hazard. o If an interior location or confined space is to be monitored, it is important to consider vapor density. o Whether the product hazards are known or unknown, most chemicals that may be found during a response have a vapor density greater than one. o If the monitoring operation is conducted outside, the technician must consider wind direction and speed when selecting sampling locations. - Area Monitor o The objective is to determine the presence and concentration of product in an area. o The IC may ask the team to develop an average exposure potential for a defined area in a given zone. o May use portable equipment, or for prolong-term incidents, fixed equipment should be used. o To measure air concentrations at a scene, photoionization detectors, oxygen sensors, explosivity meters, and chemical sensors can be combined. Confined Spaces - Space or enclosed areas are not intended for continuous occupation, have limited (restricted access) openings for entry or exit, provide unfavorable natural ventilation, and have the potential to have a toxic, explosive, or oxygen-deficient atmosphere. - The atmosphere must be tested for hazards. Cargo Containers - Materials can be transported without the knowledge of port personnel. - Take extreme care because of the unknown conditions. - Attempt to monitor through open vents. Sampling Techniques - Hazmat technicians may be required to collect samples of contaminants to support medical treatment, determine how to best mitigate the situation, and determine the type of decontamination required. - Some incidents may be of a criminal nature, and samples can become evidence. Sample Collection - The particular type of material present and the amount of the material will determine the sampling method and equipment. - Safety samples should be collected as per AHJ requirements and may later be used as evidence. Field Screening Samples - Technicians must conduct field screens to eliminate specific hazards before samples can be sent to the laboratory. - Ensure the safety of individuals involved in packing, transporting, and performing lab tests on the samples. - Consider the potential for the presence of explosives. - Check for crystalized materials around caps and containers as there are indicators of potential shock-sensitive explosives and reactive chemicals. - When conducting field screening, technicians will need to establish a suitable work area that is well- ventilated. - When using destructive field screening, leave enough material to be tested by laboratories for evidence purposes. - Field screening samples test at a minimum: o Corrosivity § Using pH paper o Explosivity § Bomb squad personnel check for explosive materials/devices o Flammability § Use a combustible gas meter to check flammability. o Oxidizer § Use Potassium iodide (KI) paper. o Radioactivity § Check for alpha, beta, and gamma radiation o Volatility § Use a photoionization detector (PID) § Flame ionization detector (FID) for volatile organic compounds - Sampling Plans 1. Preparing containers before entering the exclusion zone 2. Recording the sample locations, conditions, and other pertinent information in field notebooks 3. Confirm sample container agrees with the overpack container number 4. Wrapping sample container in absorbent material 5. Placing the sample container in an overpack container and sealing it with tamperproof tape 6. Completing the chain-of-custody form 7. Placing the sample and chain-of-custody form in an approved transport container o The sample plan should also include sampling protocols for: § Protecting sample and evidence § Field Screening samples § Labeling and packaging § Decontaminating samples and evidence A minimum of two individuals are recommended for sampling o Sampler – Takes samples and handles all pertinent equipment o Assistant – Handles only clean equipment and provides it to the sampler when needed.  o The law enforcement AHJ, in cooperation with the receiving laboratory and the transport vehicle operator, is responsible for the safe packaging and transportation of evidence. - Chain of Custody for Sampling o A continuous change of possession of physical evidence must be established in court to admit such material into evidence. For physical evidence to be admissible in court, an evidence log of accountability must document each change of possession from the evidence’s discovery until it is presented in court. o Chain of custody must be used for the following purposes: § Public safety sampling § Environmental § Documentation § Public health § Identification Evidence Collection Techniques - Hazmat crime scenes fall under two categories: o A traditional crime where hazardous materials are involved. o A hazardous materials WMD or CBRNE event where the intent is to cause harm to persons, property, or the environment. o Technicians must work with law enforcement to preserve and protect potential evidence. o Technicians may be called to assist law enforcement. Evidence Collection - Evidence must be documented, collected, preserved, and packaged with careful attention to scene integrity and protection from contamination or harmful change. - Maintain scene security throughout processing and until the scene is released. - Lay out the investigative evidence collection grid system. - Document the collection of evidence by recording its location at the scene, date of collection, and who collected it. - Collect each item identified as evidence. - Obtain control samples. - Provide blank samples. - Immediately secure electronically recorded evidence and remove it in a secure area. - Identify and secure evidence in containers at the crime scene. o DiEerent types of evidence require diEerent containers. o Follow the lab requirements for analyzing the samples regarding the types of containers and the number of samples to collect. - Package items to avoid contamination and cross-contamination. - Document the conditions of firearms/weapons designed to render them safe for transportation and submission. - Maintain evidence at the scene in a manner designed to diminish degradation or loss. - Transport and submit evidence items for secure storage. Chain of Custody for Evidence - A written history that must include each person who maintains physical control over the item. - Each person in the chain of custody is a candidate for a court subpoena. Evidence Collection and Preservation - Will determine the sampling method and equipment required. - Initial monitoring should indicate the general characteristics of the potential threat and the type of contaminant that is present. - Wipe samples can be used for visible or suspected contaminants on surfaces. - Smaller samples can be collected by using a swab with a scoop or spatula. - Staples can be used to scrape surfaces. Maintenance of Monitoring, Detection, and Sampling Equipment - Technicians must know the proper use and operation of monitoring equipment and apply the information to response objective tactics. - Technicians must be able to maintain and test equipment. - Technicians must be able to understand the hazards and what bearing these dangers have on detection and monitoring equipment. o Damages o Inaccurate readings o Failure of equipment