Final answer:
Vapor suppression is an action taken to reduce the emission of vapors at a hazardous material spill by using foam, vapor barriers, or chemical agents.
Step-by-step explanation:
The spill control and confinement tactic that is an action taken to reduce the emission of vapors at a hazardous material spill is Vapor suppression. Vapor suppression involves using a material or method to prevent or reduce the release of hazardous vapors into the air. This can be achieved through the use of foam, vapor barriers, or chemical agents that inhibit vaporization.