Which of the following is NOT a use of Toxic Gas Sensors?

Toxic gas sensors are specifically designed to detect and measure the concentration of harmful gases in the environment, ensuring safety for individuals who may be exposed to those substances. Each of the gases listed, such as hydrogen sulfide, sulfur dioxide, and ammonia, are toxic and present specific hazards; therefore, sensors for these gases are integral to protective measures in hazardous environments.

Testing for oxygen deficiency, however, falls outside the typical scope of toxic gas sensors focused on detecting toxic vapors or gases. Instead, this function is performed by oxygen sensors, which measure the concentration of oxygen gas in the air. They are important for ensuring a safe atmosphere, especially in confined spaces or areas where gas displacement might lead to oxygen deprivation, but they do not detect the presence of toxic gases themselves.

Thus, the option regarding testing for oxygen deficiency is not a typical use for toxic gas sensors, making it the correct choice in this context.