A variety of alpha emitters have been used to ionize the air around the tip of lightning rod tips (e.g., radium, thorium, americium). Radioactive lightning rods are pretty much a thing of the past in the U.S., but they are still employed in many other regions of the world.

The examples shown here employ radium. Radium activities would generally be in the 1 -10 mCi range. The radium is applied to the circular disks.