These are non-metallic oxides,commonly represented as SOx. All nonmetallic oxides, in a chemistry point of view are highly reactive and thus, unstable and gets stability after forming acidic substances with water. These acids are harmful to the biotic life, because all the biotic components do have about 70-75% of water. Beside biosphere, all other environmental segments like lithosphere and atmosphere have the presence of hydrosphere i.e water. As a result, ultimate fate of these gases in this environment is to dissolve in water producing strong acids and becomes corrosive even to the abiotic components. Thus, in the environment, these gases are always harmful and corrosive in nature and in absence of water/moisture in any environment, the chemistry of these gases may be different.

Thanks Phani. This is helpful.