Clean air, clean water. That's the image that's projected onto the silver screen, but actually Los Angeles is a cesspool of toxins. The good news is that Los Angeles rates at #6 on the list (under New York's #4), but that still doesn't make it a very healthy place to live. The air quality is the worst, with smog creating a thick layer of poison over the city, and the water quality is literally poisonous containing elements like nitrate, arsenic, and methane.