'''Particle''' is a very small piece of material. The biggest natural sources are [[dust]], [[volcano]]es, and forest fires. Aerosols or fine particles, are tiny particles of solid or liquid suspended in a gas. | '''Particle''' is a very small piece of material. The biggest natural sources are [[dust]], [[volcano]]es, and forest fires. Aerosols or fine particles, are tiny particles of solid or liquid suspended in a gas. |