Volcano rock deodorizers, also often called Zeolite deodorizers after a volcanic mineral, pull odors from the air naturally without the use of harmful chemicals. You will often find bags of such rocks sold in pet supply stores for use near litter boxes or in dog kennels. The rocks usually work for many months but will need to be recharged in order to replenish their odor-control abilities.
Place the rocks on a baking sheet. If they are in a resealable bag, remove them first and spread them out on the sheet in one layer. Otherwise, place the bag as flat as you can on the sheet so the surface area is as evenly distributed as possible.
Take the sheet with the volcano rocks outdoors. Place it on a sturdy surface, such as a table or driveway, in the sunlight.
Leave the rocks outdoors in the fresh air and sunlight for at least 24 hours. If the rocks are enclosed in a mesh bag, turn the bag over at this time to expose the rocks on the bottom to sunlight and fresh air. Leave it for another 24 hours.
Repeat the recharging procedure every six months or when the rocks seem to lose their odor-control ability.