Which of the following is NOT one of the six common TIH gases?

The correct choice identifies ethyl alcohol as not being one of the six common toxic inhalation hazard (TIH) gases. TIH gases are materials that can pose a significant threat to human health and safety when inhaled and are typically associated with chemical spills or releases during transportation.

Common examples of TIH gases include ammonia anhydrous, chlorine, hydrogen, and others that are noted for their potential acute risks to life and health. Ethyl alcohol, while it can be hazardous, especially in high concentrations, does not fall into the category of TIH gases in the context of the Emergency Response Guidebook (ERG). It is more commonly recognized in discussions of flammable liquids rather than toxic inhalation hazards, which primarily encompass gases that are harmful upon inhalation due to their chemical properties and impact on the respiratory system.

By pinpointing ethyl alcohol as the outlier, it becomes clear that the focus of TIH gases is on substances that have an immediate and severe impact on health when inhaled.