Kortum concedes that the issue of reduced carbon monoxide emissions, which is supposed to be a function of MTBE in reformulated gasoline, is one in which there is currently a lot of disagreement. And there's plenty of disagreement from the experts. Kaufman, for instance, says MTBE is actually increasing NOx emissions making it harder for cars to pass smog checks and, thus, costing the consumer more to get their cars fixed. Kauffman also said that MTBE itself is a VOC which, when mixed with NOx, helps produce ground-level ozone. He thinks something else, possibly formic acid, which he believes may actually be produced from fuels with MTBE, is the real problem.
Formic acid is known to be extremely irritating to the respiratory system.
The EPA's Kortum also concedes that MTBE is leeching into the water supply as many critics have charged. The California Air Resources Board ignored warnings from the Environmental Protection Agency that gasoline additive MTBE might be carcinogenic before requiring it in every gas tank in the state. He later added, however, that the board never thought that levels of MTBE in the environment would ever reach a point that would adversely affect people's health. Wortman also stated that he thought that the board knew even before MTBE usage became mandatory in the state that the chemical wasn't healthy for people. According to Wortman, the main reason that the California Air Resources Board passed the resolution was because of political pressure.