The various atmospheric pollutants which affect our monuments are discussed. The monuments and other material remains are not inert to permissible levels of gases and particulate matter. Concentrations of atmospheric pollutants equal to zero should be regarded as a safe level. The science of the decay of materials is very complex; as such, suggesting acceptable levels would prove detrimental to the objects in the long run. Once the process or effect of pollutants sets in, damage cannot be reversed. Famous Indian monuments and monuments in other countries which have been damaged by air pollution are discussed, as are the effects of air pollution on the Taj Mahal and some of the measures taken by the Archaeological Survey of India.