I'm not sure it even prevents pollution. I am not sure you understood what I was trying to say though.
My point was that gasoline is sold in multiple octanes with names like "regular', "premium" or "super-premium" etc. depending on the gas station. The premium gas versions are sold for a ridiculous price over the regular gasoline with the price premium not reflecting the extra cost to produce the "premium" gasoline, but rather an exaggerated market price. The people paying the price are either captive because they have a car with a turbocharger or similar that actually requires the premium gas, or they are people who don't actually understand the point of the gas and think that putting it in a car that doesn't need it might actually make it perform better.
The difference between the different variants is the octane rating of the gasoline. The octane rating has to do with the fuel's anti-knocking properties. Knocking is when there is improper combustion in an engine cylinder. It can be premature combustion, or a staccato combustion, etc., just not a smooth burn. The higher octane the gas, the smoother the burn tends to be. As for the name, there are various types of hydrocarbon compounds in gasoline. Some of them are alkanes, cycloalkans and isoalkanes like pentanes, hexanes, heptanes, oxanes, etc., then there are alkenes, aromatics (basically benzene and benzene based compunds), etc. Anyway, one of them is called iso-octane, but that is an industry name. There is another hydrocarbon that is also found in gasoline that meets the proper structural requirements to be iso-octane but, ironically, it has a low octane rating (a lot of octanes do). Anyway Iso-octane (the industry-named version) has very good anti-knocking properties and, on the octane scale, it is the baseline at 100. Traditionally, refineries used fractional distillation and cracking to control the mix of high octane rated compounds in gasoline, but also some interesting additives, that I will go into further down.
In an actual engine, for most cars, octane rating doesn't matter any more. 87 octane gasoline is fine for operating in most cars and they have knock sensors and other systems to figure out exactly the right mix and timing to prevent knock. Where this doesn't work is various kinds of high powered engines, for example with turbochargers, where there just isn't enough leeway to make those kinds of adjustments so if the fuel is low octane, either performance has to drop, or there is engine knock, which is not good for the engine and, of course, also lowers performance. So, some cars really do need high octane gasoline. Of course, it's rare that they would actually be damaged by it, the computer would just sacrifice performance to protect the engine. Most of the people who buy those kind of cars these days aren't actually that interested in real performance of course, because hybrids and EVs can outperform them (there's an argument that can be made about BEV weight, but if anyone were that truly concerned about performance, they wouldn't worry about range and an EV with a very light battery would be the clear winner). Anyway, to the companies selling gasoline, these people are a captive market for high octane gasoline. Those people, and then the people who buy it for their cars even though their cars have no need for it.
So, for octane rating in gasoline, the obvious thing to increase is iso-octane, of course, but the industry is always happier to find another way. One of those ways was a wonderful chemical called tetraethyl lead. Unlike the hydrocarbons I mentioned, it didn't have high octane itself, but mixed in gas in tiny percentages and burned, it increased the octane level dramatically by slowing down and smoothing out the combustion. Of course, I think we know how leaded gasoline worked out both with its direct effect on health and that it was not compatible with catalytic converters. Then there was MBTE, which worked both by having its own high octane rating, but also by releasing oxygen when burned. Also BTEX with also has high octane and because the benzene content resulted in a slower burn. Of course, both were really toxic and BTEX caused a lot of particulates. So those were phased out.
So, with those old favorites phased out, that means that high-octane ethanol is one of the primary ways to boost octane levels in gasoline now. Sure they use refining and cracking too, but then ethanol usually is used to take it the rest of the way, and it's convenient because of the subsidies. Many researchers are not really sure that corn ethanol actually is more ecologically sound due to its own externalities. Ultimately though, the oil companies ended up with a fairly good relationship with it because it gives them a cheap octane booster.
So, that's why I said it was a silver bullet... for the oil companies. Because they can use a cheap product to help turn something into a premium product and make a nice margin on its sale.