A leaf blower, often known as a blower, is a gardening instrument that propels air through a nozzle to move leaves and grass clippings. Leaf blowers are powered by either gasoline or electric motors. Traditional gasoline models had two-stroke engines, however recently four-stroke engines have been introduced to partially address air pollution concerns. Typically, leaf blowers are portable machines or backpack-mounted equipment with a handled wand. The second option is more ergonomic for extended use. Larger units may be equipped with wheels and a motor for propulsion. [1] These are commonly referred to as “walk-behind leaf blowers” because they require manual propulsion to function. Some machines known as blower vacs may also vacuum leaves and small twigs and shred them into a bag.