Fume smell

Starting today 3/24, I noticed that when driving to work my car had a strange fume coming from the air vents. On the way back from work I smelled it again when driving and it was a very strong odor. I noticed that when I turned the ac off the smell went away. Idk if its because no air flow was coming in or what, but I am worried it is an exhaust leak. I didn't hear any sounds coming from the car when I was driving but im scared to drive it to work tomorrow and j dont have money for a mechanic at the moment.