The durability of the Taj Mahal has been subject to controversy for more than a decade due to an increase in the SO₂ level at Agra allegedly caused by operations of a new refinery. The failure of the lime plaster in some places has been attributed to this increase in SO₂ level. Detailed physicochemical, petrographic, infrared, and scanning electron microscopy studies were carried out on these plasters, but no evidence of degradation due to SO₂ damage was found.