Emergency response to a refinery fire, overturned tanker, terrorist alert, or chemical leak must include using atmospheric monitors to protect first responders investigating the incident. Firefighters, hazardous materials (HazMat) teams and law enforcement personnel should follow these ten reminders to safely and efficiently measure and monitor the presence of gases and vapors.

1) A clear understanding of the capabilities and limitations of each detector is critical. Purchasing decisions should consider past and potential response situations to evaluate the types of hazardous atmospheres that may be encountered.

Gas detection devices are used to qualify and quantify the hazard; most common are single-gas monitors, multi-gas monitors and photo-ionization detectors (PIDs). While PIDs can be used as gross detection devices, single and multi-gas detectors can detect multiple gases specifically and simultaneously.

2) A variety of detection options in an emergency helps identify and specify gases and vapors that could be hazardous. At the minimum, an emergency response team should be equipped with a photo-ionization detector for gross detection of volatile organic compounds (VOCs); a multi-gas detector capable of monitoring oxygen, combustible gases, and two or three toxic gases such as hydrogen sulfide, carbon monoxide and chlorine; and possibly a single gas monitor for a unique toxic sensor, such as phosphine or hydrogen chloride.

3) Use instruments according to the manufacturer’s instructions. Know capabilities and limitations prior to first use. Before using the equipment, consider the following: calibration and maintenance, training, basic operation and interpretation of the readings.

4) Designated monitors should be reserved for the emergency response team and not utilized by other work crews. Even if few incidents involve gas or chemical hazards, the equipment should be properly serviced and ready to go in any emergency response.

5) Gas detectors and PIDs require calibration against a standard with a known concentration of gas. Exposure to harsh environmental conditions, rough physical stress, or high concentrations of gas can jeopardize the accuracy of the instrument. A maintenance routine that guarantees each instrument is calibrated prior to the next emergency is critical.

6) Pay close attention to age-sensitive components. This includes sensors, batteries and calibration gas. Monitor expiration dates and performance degradation. Automated instrument maintenance systems that automate calibration, battery check, sensor performance, calibration gas check, and general instrument condition help to ensure your instruments will be ready to go when needed.

7) Know how to use your equipment and understand how to interpret the readings. This provides a base for critical decision-making during an emergency response call. Typically the manufacturer will include an instruction manual with the product, and offer alternative training tools such as training CD or video, online courses, or instructor-based training classes.

8) Get trained on detection principles. It's important to understand how gas readings can be affected by the total composition of the air. For instance, low oxygen content in the atmosphere is not only a hazardous atmosphere that presents the potential for asphyxiation, but it also will affect the ability to monitor for combustible gases. Also, if oxygen content is below normal concentration, something else is present in the atmosphere displacing the oxygen, and that gas may be very dangerous.

9) Understanding gas and vapor properties assists in rational management of the situation. When assessing atmospheric hazard potential, measure the concentration where the gas is expected to settle according to the weight of the gas compared to air, so that an accurate reading can be recorded. Also, some toxic gases generate a cross-interference with other toxic gases that may skew the readings.

10) Responders to incidents that definitely or may involve gas or chemical vapors should protect themselves with HazMat suits and other personal protective equipment (PPE) until the hazards are fully identified and mitigated. Gas detectors and instrument readings are only as specific as the sensors installed. Depending on the mix of sensors installed in the monitor, other constituents of a highly toxic atmosphere may be present and may go unnoticed due to the specific sensors installed. Most gas detectors have interchangeable sensors, but the complexity of emergency situations could not guarantee the right sensors are installed prior to arrival on the scene.