If I over crowd my livestock their very own feces will make them unhealthy. Bones is correct too many folks crowed together. Ive been to Southern Calif when the wind was blowing from the Salton Sea and its was terrible. All the citys stink. I can drive up I57 and about Kankakee I can see the dark cloud. and pretty soon I can smell it. St Louis used to be the same. Now the factorys are gone its not as smelly. Mt Vernon Indiana still smells. However when you look at the big picture those places are a small % of the total area of the planet. They don't amount to diddly squat.