What is ionized air? What are its uses ?

Ionised air which has been charged either positively on negatively.  The positive charge is given by removing an electron from the oxygen atoms.  When an electron is added to the oxygen atom, the atom acquires a negative charge.    Ionized air is produced by making air to pass through an electric field.

Most ionized air is negatively charged.  This helps the air to attract dust and other floating particles such as germs and pathogens.  For this reason, ionized air is used in hospitals as a disinfectant.  Thus air ionization has emerged as an effective air cleaning technology.

You would have noticed how the sky appears clearer after a rain.  This is because the air is charged after a rain due to the electric effects of the rainfall.  This attracts the dust particles giving a clearer appearance.

Ionized air also carries an inherent risk.  During the process of ionization, ozone (O3) is also produced.  Ozone can be toxic to humans at high levels.  Hence, ionized air used in medical applications should have low ozone generation.  

Ionized air is also used in electronic to prevent accumulation of static charge.  They are also used in industries to prevent charge accumulation in fabrics, paper, plastic, etc.