For the average city-dweller's health, E85 emissions confer a mixed blessing, not necessarily an outright benefit. They contain less carbon monoxide than gasoline, which can aggravate heart disease. They also cut nitrogen oxides, those notorious perpetrators of acid rain, smog and haze, to half the level of gasoline [source: Yanowitz]. Lastly, E85 lowers emissions of two cancer-causing substances, benzene and 1,3-butadiene, below gasoline but dramatically boosts two other likely carcinogenic substances, acetaldehyde and formaldehyde. U.S. government-funded researchers concluded that the total toxicity for tailpipe emissions from gasoline and E85 is the same [source: Yanowitz].
The biggest benefit of making ethanol from cellulose is the inexhaustibility and convenience of cellulosic biomass. It's more available than corn or any other source of ethanol, or for that matter, any existing source of fuel. When done wisely, cellulosic ethanol production can get rid of waste and make fuel. If you're of the anti-greenhouse gas persuasion, its production and burning releases less greenhouse gas than gasoline. It has other environmental and clean-air benefits, which you read about in the last section. If you dislike oil drilling, oil importation, want an alternative at the gas pump when oil or corn prices increase or think there's a limit to how much fuel corn can make, cellulosic ethanol provides an alternative.
That's the good news. What about the bad news?