Superior hydroxyls are provided which have effects on organic and inorganic compounds and/or pollutants over substantial periods of time and/or at substantial distances from where the superior hydroxyls are generated. Also provided is a hydroxyl generator, in which UV-lamps are positioned such that the coronas which they produce when emitting UV-radiation fill substantially all of the interior space of the hydroxyl generator. The coronas overlap each other by a maximum amount of between 5% and 25% of the radius of each corona.