Hi, daun. If what you are describing is what it seems, the gas is basically methane. The good news is that it will not, to the best of my knowledge, give you any long term or short term health problems in low concentrations. The bad news is that it is flammable and explosive. It is also deadly in high concentrations.
Every house in the country that has indoor plumbing has vents to above the roof line for sewer gas. But I am amazed that a school would have it vented into an indoor space. There are major health, safety and liability issues. I just can't conceive of any building code that would allow this. I would certainly alert the administration to this, and if they are unwilling to do anything about it, get the building inspector and fire marshall involved. I don't know what level school you are in, but you might ask a chemistry teacher what he/she thought of having a methane gas vent in occupied space. You will probably be able to find a lot more information on the web.