SACRAMENTO, Calif. — The California Air Resources Board (ARB) has completed an 18-month evaluation of decamethylcyclopentasiloxane (D5) silicon, the solvent used in GreenEarth. According to a letter published at its website, ARB has determined that D5 is an “acceptable drycleaning solvent alternative” to perchloroethylene, but is not eligible for the state’s grant program.