Fossil Fuel Residue

Sulphur dioxide develops when burning fossil fuels. After oxidation and reaction with water it forms sulphuric acid (H₂SO₄) that can contribute considerably to the atmospheric corrosion of zinc and steel.

Burning resinous woods, CCA-treated timber, low-grade coal or oils with a high sulphur content can increase the fall-out deposit or condensate from flue gas.

Exhaust fans can cause similar problems when corrosive gases are not filtered at their source.