What comes out of the exhaust of a vacuum pump during the early part of evacuation?

During the early part of evacuation, a vacuum pump expels air and moisture from the system, which can include water vapor, dust, and other contaminants. This initial exhaust may contain volatile organic compounds (VOCs) or residual gases from the environment. As the vacuum level increases, the exhaust will primarily consist of lower-pressure gases being removed from the chamber. Overall, the composition of the exhaust will vary based on the specific application and the conditions of the vacuum system.