Empty Cans = Recyclable Metal
A completely empty aerosol can is recyclable scrap metal, and many curbside programs accept it along with other metal cans. "Empty" means truly empty: nothing sprays out, there's no hiss of pressure, and you don't hear liquid sloshing when you shake it. You can usually leave or remove the plastic cap depending on your local program. Because acceptance varies, confirm aerosols with your local recycler.
Never Puncture or Crush Them
Do not crush, puncture or flatten an aerosol can at home. Even a can that seems empty can still hold pressurized propellant, and puncturing or crushing it can make it burst or ignite. Leave the can intact and let the recycling facility handle it. (Only industrial facilities with approved, vented, filtered equipment should ever puncture aerosol cans.)
Non-Empty or Hazardous = HHW
A can that still has product in it is not curbside-recyclable — and if it held something hazardous like spray paint, insecticide, pesticide or certain cleaners, a partially full can is household hazardous waste (HHW) and belongs at an HHW drop-off site or collection event, not your bin. The EPA added hazardous-waste aerosol cans to its "universal waste" rules in 2019 to make collection easier; household cans are technically exempt, but the practical rule stands — don't put a can with leftover hazardous product in the recycling.