> "Balloon Grade" Helium represents a slightly impure Helium. While there is no scientific definition of this quality, it is often accepted that the purity of "Balloon Grade" Helium is around 99%

https://www.quantum-technology.com/recover/balloon-grade-hel...

Sounds high, but not pure enough for MRI applications, and it isn't currently economical to reliquefy without shipping it to a processor.

> Manufacturers have stated that this wasted helium is considered a ‘recycled product’ as it would have been lost to the environment had it not been captured and re-purposed. If the balloon market demand declined, manufacturers would have to re-evaluate other markets and consider the possibilities of re-liquefying it. Re-liquefying is currently considered uneconomical from the locations of where the filling application take place.

https://www.partysafe.eu/balloon-and-gas-helium

Also it's small, but not insignificant, sector of the market:

> "A reasonable estimate is that latex 'party' balloons and their foil equivalent account for between 5% and 7% of the total helium usage."

https://www.theguardian.com/science/shortcuts/2012/dec/11/sh...