The EPA report has some interesting things, referencing all the members of this thread’s fortissimo symphony orchestra: leaf blowers/vacuums, trimmers/edgers/brush cutters, chain saws, snow blowers, mowers.
From the WSJ summary:
Four-stroke engines are more efficient, but two-stroke engines are inexpensive and pack more power. They also run in any position—even sideways or upside down—a feature made possible by the way they are lubricated.
Four-stroke engines must operate in a generally upright position because their lubricating system would spill oil, if the engine were turned upside down
Two-stroke engines lack a separate lubrication system; their oil is mixed in with the gasoline used for fuel. Some of it lubricates the engine, and some of it burns up, but a significant amount escapes through the exhaust.
All gasoline engines expel some unburned fuel in their exhaust, but two-stroke engines release a higher percentage.
ETA: Post #38 by Dolomite mentions the engine configuration in a different context.
The filthiness of small engines is nothing new, but the disparity compared to cars has gotten worse over the years as cars have gotten cleaner and cleaner. There’s a lot of emissions control tech on a car, and it can be justified because the increment in cost and weight is a small percentage of the car’s total cost and weight. Not so for a small engine: if you add liquid cooling, closed-loop fuel injection, EGR, an evaporative emissions recovery system and a catalytic converter, your handheld string trimmer ends up weighing 40 pounds and costing $1000.
I know this is an old thread but didn’t California ban two stroke engines? I vaguely remember some noise about such a laq a few years ago and that was the reason personal watercraft moved from two stroke to four stroke motors.
I had thought so too, but it seems no one told the gardeners. I do a lot of walking around my neighborhood and they’re all using gas two-stroke equipment.
As far as noise, it happens the guy who “gardens” my current rental actually uses an electric blower which he recharges here sometimes, but it is so damn loud it made me jump out of my chair one day when he showed up unexpectedly (his schedule is irregular; I suspect it depends on his binge drinking cycle).
I once lived in an apartment, facing another higher class apartment complex just across the street. One day I started hearing a new noise. They had hired a boy to put on a leaf blower, and walk around the property from 9 to 5, machine idling, and every time he saw a leaf on the sidewalk, he would rev it up and blow it onto the lawn. I phoned city hall. They phoned the apartment complex. The boy was reassigned to some other quieter task. Or, sadly, maybe fired.