Someone already mentioned burning oil, I'd like to also mention coal which makes oil look very clean by comparison. Coal is a few ppm uranium, arsenic, and othe

Someone already mentioned burning oil, I'd like to also mention coal which makes oil look very clean by comparison. Coal is a few ppm uranium, arsenic, and other unpleasant metals (this is from memory, but it has lot of impurities). We burned literally billions of tons of it, putting thousands or tons of these metals into the atmosphere in the process. Also, leaded gasoline