Which statement best defines an aerosol?

• A. A suspension of solid or liquid particles in a gas (usually air).
• B. Bio-aerosol
• C. Cloud
• D. Dust

Answer: (A)

An aerosol is a suspension of solid or liquid particles in a gas, usually air. This broad idea covers many forms you encounter in occupational hygiene, such as smoke, mist, and dust particles floating in air. A bio-aerosol is simply a subset where the dispersed material is biological, like bacteria or pollen, but it still fits the general definition. A cloud, while made of droplets in air, comes from condensation and is a specific atmospheric phenomenon rather than the general particle-in-gas concept. Dust is a common example of airborne particles, but the fundamental definition remains the suspension of solid or liquid particles in a gas, which is why the described statement is the best fit.