A hair dryer cannot operate in a vacuum. Hair dryers work by using the surrounding air to generate a flow of hot air that dries and styles the hair. When you turn on a hair dryer, it pulls in air from the surrounding environment, heats it up using a heating element, and then expels the hot air through the nozzle.
In a vacuum, there is no air to draw in and use for the hair dryer's operation. Without air, there would be nothing for the hair dryer to heat and blow out, rendering it ineffective in a vacuum environment.
Additionally, most hair dryers are designed for use in regular atmospheric conditions, and attempting to operate them in a vacuum or low-pressure environment could potentially damage the heating element or other internal components.
In summary, a hair dryer needs air to function, so it cannot operate in a vacuum.