> but I guess more pollution added up to the surrounding borroughs in addition to more traffic

Why? Fewer cars into Manhattan means fewer cars through the boroughs. And even if they all diverted, you’re still looking at less idling and less stop and start braking.

The article speaks to this as well, "Pricing led to a drop in pollution across the greater metropolitan area, according to the study, published in the journal npj Clean Air."

So while this was/is a common sentiment about congestion pricing, looks like it luckily didn't pan out.

This was a common anti-congestion pricing talking point, but it ends up not being the case. People either don't drive into the city, or they take transit.

The study found the opposite: people are picking healthier choices throughout the region. This makes sense: if you switch to taking the train, in addition to not driving in the congestion zone you also aren’t driving the distance between the closest train station and Manhattan, which for many people will be more engine operating time than they spend in the zone itself.

Good question, this happened in London for sure, congestion charging increased the net pollution from vehicles but reduced the metrics inside the city, probably not much either way.