What kinds of pollutants are ruining Taj Mahal's white marble revealed

Scientists have shed light on what kinds of pollutants are discoloring one of the world's celebrated wonders, Taj Mahal.

Mike H. Bergin, Sachchida Nand Tripathi and colleagues note that Indian officials have tried to reduce the effects of pollution on the Taj Mahal by restricting nearby traffic and limiting local industrial emissions, but despite regulations and an occasional deep clean, the domes and minarets continue to accrue a layer of soot.

The researchers analyzed particles in the air and on marble samples near the main dome over several months and using a novel method they developed, the team estimated how these specks reflect light and therefore affect the color of the building.

They conclude that black carbon and brown carbon from the burning of trash, fuels and other materials are among the primary pollutants tarnishing the Taj Mahal. In the future, their approach could be used to craft strategies to address the chronic yellowing and improve air quality, they say.

The study was published in the ACS journal Environmental Science and Technology.