A 2017 Time article discussing the crumbling, wearing out, and water damage of France's Notre Dame Cathedral prior to the 2019 fire writes (emphasis added):
Notre Dame, which looms over the capital from an island in the center of the city, is a constant reminder of Paris’ history. It has seen more than its share of epic dramas, including the French Revolution and two world wars. But now there is another challenge. Some 854 years after construction began, one of Europe’s most visited sites, with about 12 million tourists a year, is in dire need of repairs. Centuries of weather have worn away at the stone. The fumes from decades of gridlock have only worsened the damage. “Pollution is the biggest culprit,” says Philippe Villeneuve, architect in chief of historic monuments in France. “We need to replace the ruined stones. We need to replace the joints with traditional materials. This is going to be extensive.”
Have scientists studied the effect of pollution on the Notre Dame Cathedral? What are the results of these studies?