It exploits a new technology, Free Air Concentration Enrichment (FACE), now being implemented at four other international sites. It consists of rings (each approximately 70 feet in diameter) of pipes that release carbon dioxide or ozone into the wind as it flows across the crop. A computer continuously measures wind speed and direction and the gas concentration within the ring to determine which pipes release the gas and how much they release. The carbon dioxide or ozone is released into the naturally moving air so that the concentration within the ring is elevated to a preset level. The rings use about a ton of carbon dioxide or about a pound of ozone a day. Downwind of the rings, the added gas is diluted quickly in the flowing air so that concentrations are close to background within about 300 feet.