The thing that surprised me about the Aliso Canyon/Porter Ranch natural gas leak is that it's coming from an underground gas storage zone which is comprised of an empty oil field that has been used for storage -- by pumping natural gas into the subterranean void in the earth.  The report I read says that the storage zone contains enough gas to run the city of Los Angeles for a month.  

Even if the natural gas they pumped into the field was pure natural gas when it filled the void down there, whatever impurities were latent in the surrounding rock and/or soil would obviously leech into the gas being stored, and now, with this uncontrolled leak going on, whatever the contents is of the stored volume, it's all leaking out.  

So it's easy to understand that radon gas (a bi-product of decaying uranium), benzene, toluene, xylene, hydrogen sulfide, sulfur dioxide, and whatever else, is all in the cocktail locals are breathing, even if they're not aware of it.  

Two area schools have been closed and the students have been moved to other nearby campuses.  But the Porter Ranch shopping center is operating without interruption while happy customers pretend that everything's fine.