I think you are probably fine. I am in college and have been in some of those situations. I also get drug tested for my summer internship. I've passed every time, but I did try to avoid being in a small room with people who were smoking. I don't know how long it takes for the THC or whichever chemicals they test for stay in your body, but if you have only have been exposed to secondhand smoke the levels of chemicals will be much lower at the start, and probably fall faster as well. As long as you stay away from any pot situations for a couple weeks or a month before the tests, you should have nothing to worry about.