How much?

How different colour come on surface which gas gives which colour

kzbin.info/www/bejne/b5rVpGeAptVgnKs

Maybe the "zero pollution" means the quality of the surface. The target material sticks clean and even to the surface of the substrate in a vacuum space where there are practically no other particles than ionized argon atoms and the target material.

Yes, zero pollution.

zero pollution? not if you consider the energy required for 10-6 Torr