Sensors in the Measurement of Toxic Gases in the Air

Abstract

AbstractThe use of sensors to measure toxic gases and vapors in air has increased rapidly due to several factors, including a growing public awareness of the hazards associated with many airborne chemicals, increasing regulatory requirements for industries using hazardous chemicals, and continuous advancements in the technology and instrumentation available to measure these compounds. The principal advantage of sensor systems for toxic gases and vapors relative to traditional sampling and analytical methods, is the ability to measure chemicals over short time periods, that is, in a matter of seconds or minutes, thus providing the information necessary to protect workers from acute health effects. Modern sensor‐based instrumentation provides many options for processing and storing measurements, thereby allowing extreme flexibility in evaluating exposures to toxic gases and vapors relative to ceiling limits, short‐term exposure limits (STELs), or longer term average concentrations based on user selectable time periods. This extreme range of options for processing data makes sensors an attractive, and in some cases, the only alternative for measuring toxic gases and vapors in air. Most of these devices can be broadly categorized as: (1) electrochemical sensors which constitute the vast majority of devices currently available for detection of toxic gases and vapors; (2) mass sensors that are based on piezoelectric materials including surface acoustic wave (SAW) devices; or (3) optical sensors that rely on the interaction of electromagnetic radiation with an analyte, resulting in some alteration of the properties of the radiation. The most common applications of sensors for measuring toxic gases and vapors in air include industrial hygiene monitoring, confined space monitoring, process emission monitoring, and leak detection.