Absolutely. This is like 20 cars on a circuit! The event itself surely doesn't cause much pollution. In F1 in general, Barcelona and elsewhere, I'd say the circus _surrounding_ it causes by far the most pollution. Logistics to/from the circuit with trucks upon trucks per team, setting up the teams' respective pits, private airplanes to/from the circuit, thousands of spectators to/from circuits, some going by yachts, many by air for at least one stint.

The race track? In the big picture, a rounding error.

I'd guess the regular traffic would just take a detour around the closed roads.

Actually, I'm now also visualizing all the surrounding roads clogged with traffic related to the race. It's not increasing my enthusiasm.