It’s leaf blower season, adding new layers of unwelcome noise to the cacophony of daily life. Leaf blowers — along with gas-powered lawn mowers, string trimmers, chainsaws and other garden equipment, also generate an alarming amount of air pollution. Some machines emit as much pollution in an hour as driving hundreds of miles in a car. A recently released report by the Maryland PIRG Foundation, called “Lawn Care Goes Electric: Why It’s Time to Switch to a New Generation of Clean, Quiet Electric Lawn Equipment,” attempts to quantify the public health risks and potential damage.