Libertarians have a slogan "your rights stop at the end of my nose".  You can dump anything you want into the air over your powerplant as long as you can keep it from floating into my airspace. Since we don't have the technology to do that (and probably never will) it means you can't dump anything into the air that will impinge on my property rights.  

Of course, you also don't have the right to poison your workers either so that implies you have to disclose to them what they they will be breathing while they work and get their consent to work under those conditions which means you would probably have a problem getting labor for your plant.  Does that explain things for you?