The Archaeological Survey of India (ASI) seems to be on a chemical cleaning spree. Having cleaned three monuments in the last few months -- Sabz Burj, Feroz Shah Tughlaq's Tomb and Isa Khan's Tomb in the Humayun's Tomb complex -- this sudden interest in making monuments spotlessly clean seems to have got conservationists across the city concerned. Bright white and covered with scaffolding, the chemical cleaning of the monuments seems to have alarmed even the residents of Nizamuddin and Hauz Khas village. "I saw them throwing buckets and buckets of water on Feroz Shah Tughlaq's Tomb. The labourers then started scrubbing the monument with iron-bristle brushes. It looked as if the monument was painted white. The ASI officials insisted that no harm would be done to the monument, but the building does not look the same. It has changed colour," said a concerned resident of Hauz Khas area who has taken photographs of the chemical cleaning process.