Pasadena put into effect a gradual ban of gas powered leaf blowers last year with fines, etc and a special incentive program to help gardening crews to switch over.
I'd say about half the crews are compliant now and the electric ones are definitely an improvement from a QoL perspective. (I'm sure the gardeners prefer the strength of the gas powered blowers) If I were king high god emperor of the area though, I'd set a mandated day of the week for leaf blowing activities. As it is right now it's highly unusual for us to go a full day without at least one house/apartment/condo having a gardening crew working for some time. (thankfully, they're usually quick). The only ones who really gall me are the guys working on Sunday because that day is a required quiet day on the city books, except for property owners themselves.