If you live in a big city, you probably perfectly know what it is like - exhaust gases. They are a great problem for city-dwellers. They harm their health, generally pollute environment and simply make life in city not that pleasant.

I think that it would be great if every mechanism, producing these gases, was supplied with a special container, which would absorb and store gases, not letting them be released into environment. And then, after this container becomes full, it can be brought to special processing plant, which through some chemical reactions transforms it into oxygen! But, probably, this dream is rather impossible to become true. :(