Its not many. They are stupidly innefficient.

https://www.edmunds.com/car-reviews/features/emissions-test-...

Given those stats, Gemini says about 8 leafblowers is the same continuous CO emissions as a private jet in flight.

I love the idea of "one Taylor Swift" becoming a standard unit of measurement for pollution!

Not many, one or two 2-stroke leaf blowers should do the trick.