Experts say that the discolouration of the Taj Mahal — the ‘browning’, as observed by the Supreme Court on Wednesday — is due to a mix of weathering as well as industrial pollution but thorough studies are required before remedial measures are implemented.
Beginning from the 1970s, activists and conservationists have raised concerns that there were various environmental threats to the Taj — from sulphur dioxide emanating from the Mathura refinery to the constituents of the marble itself. This has, at various times, triggered restoration work as well as restrictions on the footfall and stricter restrictions on emissions. However Agra remains among the most polluted cities in the world, according to data made public by the World Health Organisation on Wednesday.
Most recently, in 2014, a study by Indian and US researchers argued that the key culprits responsible for the discolouration were: particulate matter; carbon from burning biomass and refuse; fossil fuels; and dust — possibly from agriculture and road traffic.
Conservationists caution that more research is required before hasty solutions are implemented. “We need to make sure that there is a genuine problem rather that just India's ‘fair and lovely’ mentality,” said Ratish Nanda, CEO, Aga Khan Trust for Culture, in an email to The Hindu .
So far there wasn’t convincing evidence that there were instabilities in the structure, and the discolouration was also due to a “natural ageing,” he added.
