I have to replace imperial units with metric units in a text, and since this is not technical writing , I have to maintain the prose style and clarity.
This is a troubling phrase: "...the air in 1 cubic foot...".
I think I can do that: "...the air in a 30-centimeter cubic region [or cubic volume]...", but since I've seen units being used wrongly before (like saying that 1 cubic foot = 30 cubic centimenters), I would like to have your opinion on this.
BTW: I'm not a native English speaker, nor have I used imperial units daily (my country uses metric).
EDIT: I can't use liters because this is describing a cubic area of space, and 30 liters (or 28 liters) is hard to picture as cube. Take a look at it on another way. When I say "this is a two-feet cubic volume", how big do you think it is in cubic feet?
Also, did you understand the diference between saying "X-feet cubic volume" and "Y cubic feet"?
EDIT2: Here is a new doubt, what is the more correct way of writing this: "the space of a 30-centimeter cube" or "the space of a 30 centimeter cube" (the difference in the hyphen).