The best source of activated carbon is a coconut shell. This is what is used in the Austin Air Cleaner. Activated carbon is the most common element in military gas masks. The Austin Air Cleaner uses a minimum of 13.5 pounds of coconut shell activated carbon and zeolite to remove odors and gases. The HEPA, activated carbon, and zeolite are combined into one large cartridge which weighs about 19 pounds.
Natural zeolite is mined from the earth.
It is a cream-colored mineral. Zeolite has exceptional abilities for capturing small molecules such as ammonia, formaldehyde, and sulfides. Air flow becomes restricted through the clean air exhaust outlet. It's very simple. Just turn the unit upside down and remove the four retaining screws holding the bottom on.