We have discussed the Future of Avgas before in this blog, and some of the predictions made there started coming true on 15 October 2008. That was the day that United States Environmental Protection Agency (EPA) changed the environmental standards for lead contamination from 1.5 microgram/m3 to 0.15 microgram/m3.
The new standard requires that the sources of lead in the United States, which includes lead smelting, airplane fuels, military installations, mining and metal smelting, iron and steel manufacturing, industrial boilers and process heaters, hazardous waste incineration and production of batteries reduce their emissions by October 2011. The EPA has named avgas as one of the most "significant sources of lead".
The new rules aren't clear as to exactly how non-industrial sources of lead, like those from burning avgas, will be impacted.
Most pilots see this as a bad thing, as this new standard will probably mean that 100LL will no longer be available to be used in the USA after 2011, but the story is more complex than that. The tetra-ethyl lead that is used in leaded avgas is a neurotoxin (i.e "brain poison"), as are all its combustion products. Those stories that you may have heard that the tail-pipe products of leaded gasoline combustion are harmless are not correct, all compounds of lead are toxic to humans.
So what does lead in the environment do? Mostly it causes mental retardation in children as well as cardiovascular disease and death in people of all ages. New research has conclusively shown that even in very low levels environmental lead causes retardation in children. In fact the EPA's own research shows that the acceptable level shouldn't be the new 0.15 microgram/m3 standard, but more like 0.02 microgram/m3, which is seven and a half times lower.
The last round of environmental standards imposing the old level of 1.5 microgram/m3 came about in 1978 and that resulted in the end of leaded auto fuel. Why wasn't unleaded avgas invented back then? The answer to that question is complex, but the short answer is that it was, sort of. A 100 octane lead-free fuel hasn't been invented, and may in fact be impossible, but a new standard was developed for 82UL. Aircraft designed for the old minimally leaded 80/87 avgas could run on 82UL, but it was never put into production. As long as 100LL was still being made no refiner was interested in making 82UL. Also 82UL will only work for those low-compression engines that can use an 82 octane fuel. For example, you can't run a Cirrus SR22 with its high-compression Continental IO-550-N 310 hp engine on 82UL, so it is not a complete solution.
Essentially because 100LL wasn't caught in the old lead standards in 1978, there was no major motivator for the fuel and engine makers to come up with either an unleaded high octane fuel or to find another technical solution. There are some possibilities on the horizon, like Unison's LASAR ignition system that will allow some high compression engines to use premium auto fuel, but in general we are still dependant on 100LL here in 2008 and just accept the lead it is putting into the environment. We probably should have spent the last 30 years developing real solutions, because it has been obvious since 1978 that leaded avgas's days are numbered.
This is all happening in the USA, how does all this affect Canada? Well 100LL is all made in the USA and shipped to Canada. So if they stop making it, it won't be available here. The Canadian volumes of avgas used are tiny and won't justify starting up Canadian refining of this difficult to make (because of the lead) product.
The key question is then, should we try to fight these environmental concerns to keep flying on 100LL? Some organizations, like AOPA, argued during the hearings before the standard was changed that 100LL should be retained, saying that "any changes that would force an immediate change in the current composition of avgas would have a direct impact on the safety of flight and the very future of light aircraft in this country."
Essentially we have a choice here: keeping flying on 100LL and accept that it will cause mental retardation in children or stop using 100LL and find something else. Which is the right thing to do?
The EPA seems to have made their choice.