Very few pigs nowadays are in pens in a barnyard. You can go to Iowa where 27 million hogs live and you will never see one of them.
I visited a large hog farm in Tidewater, Virginia. I was impressed by how clean and modern it looked.
Then the smell hit me.
There was once a huge chicken processing plant in my home town. It stunk to high heaven. Then in the last few years before it closed they somehow figured out a way to kill the odor. I have no idea how but they did.
Maybe they can do the same with hog farms.