Grant Gerlock:

Well, E15 wasn't even approved as a motor fuel until, in 2011, EPA approved it for most cars and trucks built after 2001.

And when they did that, they kept this restriction for about three-and-a-half months over the summer from June to mid-September. And the reason they did that was because of smog. That's the concern. E15 is more volatile than regular gasoline. And so it's a bigger risk for causing ozone pollution.

There are many parts of the country where smog is a problem during the summer months. And if there's smog pollution, it can be bad for your health, especially if you have asthma or COPD or other respiratory illnesses. So they try to keep that smog down.

That's one reason E15 wasn't allowed to be sold during that time of the year. But the trick, especially when you talk to ethanol — ethanol groups about this, is that during those summer months, when you can't buy E15, you could still buy E10, the 10 percent blend of ethanol, which has about the same impact on ozone and those smog issues.

So they really saw that more — as more of a technicality. The reason E10 can be sold in the summer and not E15 is because E10 was given a waiver, and E15 didn't have that waiver. That's what they're looking for the EPA to do. That's what the president is directing the EPA to do.