Five Chemicals Deleted as Smog Precursors

A solvent and four chemicals that could substitute for stratospheric-ozone-depleting substances are no longer considered smog-forming compounds by EPA. The agency has granted a petition by Lyondell Chemical to exclude the solvent tert-butyl acetate (TBAC) from materials classified as volatile organic compounds that can form ground-level ozone, producing smog. TBAC, used to make drugs and pesticides, can potentially substitute for smog-forming solvents such as xylene and toluene and could be used in paints, inks, and adhesives, EPA says. Lyondell is restricting its production of TBAC until it completes chronic toxicity tests on the compound, the agency adds. In addition, the agency excluded hydrofluoroether-7000, HFE-7500, hydrofluorocarbon 227ea, and methyl formate from its definition of VOCs. These compounds, used as refrigerants, fire-suppressing compounds, and propellants, are environmentally preferable substitutes for chlorofluorocarbons and hydrochlorofluorocarbons that deplete Earth's protective stratospheric ozone layer, according to EPA.