Delhi’s iconic 17th-century Red Fort , a UNESCO World Heritage Site and symbol of India’s rich Mughal heritage, is showing signs of distress, and the culprit is the city’s worsening air pollution. Scientists have found that the monument’s signature red sandstone is gradually turning black due to a chemical reaction triggered by pollutants in the air. Also Read | Rishab Shetty's Kantara 1 maintains momentum, nears ₹250 crore
What’s behind the Red Fort’s darkening walls?
The study, conducted between 2021 and 2023 and published in the Heritage journal in June 2025, is the first detailed examination of air pollution’s chemical impact on the Red Fort. Scientists collected wall samples from different sections of the monument and compared them with Delhi’s air quality data. Also R