I'm convinced that these leaf blowers cause half of the particle pollution here in LA. One day, the leaf blowers blow the dust into the street towards the other neighbor, only so that the next day the other neighbor blows the same dust back to the other side again. This is a great business for the gardeners, they are paid for pushing the same dust around the block ad infinitum.
The second reason they are a nightmare for the environment is what they cause of water consumption. Yes, you read that right. The same dust pushed around lands onto the cars parked on the street, causing them to need much more frequent trip to the car wash than they otherwise would. It has a a massive impact.
California can not claim to care about the environment before they ban leaf blowers.