Defining aerosols by physical and chemical characteristics

An aerosol is a suspension of fine particles in a gas, usually air, and is generally taken to include both solid and liquid particles with dimensions ranging from a few nanometers up to around 20 micrometers in diameter. This paper presents an overview of the various physical and chemical characteristics of aerosols. It also highlights some gaps in the existing knowledge on aerosols and throws open certain ideas on which research could be initiated.