A new study has identified the pollutants that are causing the marble of India’s iconic Taj Mahal to turn yellow. The discoloration of the white marble has long been a concern, but the latest study could help in drawing up more targeted measures to protect the 360-year-old famed monument of love.
Researchers say years of burning fossil fuels, biomass and garbage as well as dust has left behind carbon deposits which are turning the white marble dome and minarets of the Taj Mahal brownish yellow.
The 17th century monument is located in the busy, industrial city of Agra in northern India.
Many have long blamed air pollution for discoloring the famed monument, but the year-long study by two American universities – the Georgia Institute of Technology and the University of Wisconsin – the Indian Institute of Technology at Kanpur, and the Archeological Survey of India have identified the specific causes.
Researchers placed small samples of pristine marble on the Taj Mahal, left them there for two months, and then analyzed the particles deposited on their surfaces.
Fossil fuels, biomass burning to blame
One of the study authors, Professor S.N. Tripathi at the Indian Institute of Technology at Kanpur, said the particles come from multiple sources.
“We have [an] increasing fleet of diesel vehicles nowadays in cities, large vehicles, trucks, that’s number one,” he said. “And that is a major emission source for black carbon and organic carbon. But biomass burning – particularly the season now – we are seeing people, when they feel cold, they burn any kind of stuff. People, maybe in houses, they are burning just wood etc., but outside the people are burning cow dung and different kinds of trash. Burning is also a major source of organic carbon.”
Activists have warned for several years that Agra's air pollution is making the Taj lose its sheen.
Over the last decade authorities have banned vehicles within 500 meters of the monument. Efforts have also been made to supply clean fuel to industries and improve the power supply to lessen the impact of diesel generators.
But despite these measures, a 2010 study found that the relentless growth of industry, population and traffic have only worsened air pollution in Agra.
Targeted protection needed
Preservationists are stressing the need for more targeted protection of the monument.
Conservationist Ratish Nanda in New Delhi said some weathering is to be expected in a monument that is over 360 years old. He believes that the single issue of discoloration should not be blown out of proportion.
Nanda stressed, however, the need for more far more intensive monitoring and greater involvement of the scientific community, and more funding to protect the Taj.
“There are lot of studies which are saying that is the discoloration happening and how it is happening, but there is absolutely no real work on what to do to prevent it,” he said. “The whole preservation mechanism of the Taj Mahal needs to change… Absolutely the one thing that is absolutely essential is to put in a regime of conservation, that whatever cleaning is done, should be sensitive and have no long term impact.”
Since 1994, authorities have been giving the monument mud pack treatments to remove the pollution stains. Modelled on a centuries-old beauty treatment used by women, it involves plastering the Taj’s surface with lime-rich clay and then peeling it off. The monument received the treatment for the fourth time in June last year, but experts warn this too could have unwanted side effects.
In 2013, nearly 6 million people visited the monument, which is considered one of the finest examples of Mughal art and architecture in India.