What are the forms of contamination?

• A. Vapor, Liquid, Aerosol, Solid
• B. Gas, Liquid, Solid
• C. Powder, Liquid, Gas
• D. Vapor, Dust, Liquid

Answer: (A)

Contamination can occur in different physical forms that affect how it moves, how we detect it, and how we control it. The four primary forms here are vapor (the gaseous form that can mix with air), liquid (free liquid contamination or spills), aerosol (tiny droplets or solid particles suspended in air), and solid (discrete particulates on surfaces or in bulk).

Vapor spreads with airflow and is addressed with ventilation and gas-detecting sensors. Liquid contamination can pool or soak into materials and often needs absorbents or cleaners. Aerosols include both liquid droplets and solid particles suspended in air, requiring filtration or local exhaust to prevent inhalation. Solid contamination consists of discrete particles that can settle or become resuspended, needing containment and cleaning.

Other options leave out one or more important forms—such as not including aerosols or treating dust as a separate category—so they don’t fully cover how contaminants can exist in real-world scenarios.