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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.”

Is pollution "the biggest culprit" in causing damage to the structure?

Two sentences before the bolded line, Time writes "Centuries of weather have worn away at the stone." This wouldn't appear to be pollution. Time also writes "Water damage to the spire’s covering is threatening the wood-timber roof, which the medieval craftsmen built using 5,000 oak trees." Again, this wouldn't appear to be pollution.

Maybe.

This study shows that natural stones (sandstones, limestones, marble) are severely affected by the emissions of SO2 and that culturally valuable objects in Europe are affected by SO2.

The problem is that

In particular, calcium oxide (lime) reacts with sulfur dioxide to form calcium sulfite:
CaO + SO2 → CaSO3

Here are the SO2 levels in France over the last 60 years. And while now the concentrations are very low, in the 60's it was more than 300 times the concentration.

And in the French Wikipedia it is mentioned that one of the main building materials were limestones.

French:

On y exploitait des formations calcaires de grande qualité : les calcaires du Lutétien, datant de 40 à 46 millions d'années, très caractéristiques de l'architecture de toute la région parisienne.

English (via google translator):

High-grade limestone formations were exploited there: the 40 to 46 million year-old limestone of Lutétien, very characteristic of the architecture of the entire Paris region.

Also is CO2 a major factor, because Calciumcarbonate was used in the construction industry

The main use of calcium carbonate is in the construction industry, either as a building material, or limestone aggregate for road building, as an ingredient of cement, or as the starting material for the preparation of builders' lime by burning in a kiln.

And like SO2, CO2 reacts with Calciumcarbonate, looking at the same study above

Of course it is hard to pinpoint down the exact amount of pollution levels per time needed to damage the stones, but nevertheless the effect of pollutants like SO2 and CO2 on natural stones is present.