This video of drone surveillance of a factory hog farm is pretty incredible. It comes from director Mark Devries, a documentarian who has worked to expose factory farms.

In it, we see a massive pool of pig waste, which contains waste from pigs that drops through flats in the concrete floor of the factory. It's pushed into an open pit.  A factory farm can produce as much waste as a medium-size city, according to University of North Carolina professor Steve Wing.

What's worse is what they do with the pig waste when the pit fills up.

"If you're familiar with a garden sprayer, they [use] gigantic versions of that," Wing said. 

That's right -- factory farms empty these pits by spraying pig waste in liquid form. The droplets of pig waste that's created is released into the air and nearby communities. In the video, residents say they can't go outside or can't open their windows while the farms are spraying hog waste.

"You think it's raining," said one person who lives nearby a Smithfield Foods hog farm in North Carolina.

Factory farms in the spot light

There has been an increase in attention on the conditions of factory farms and their effect on the environment. Last year, Rolling Stone published an in-depth investigation into factory farms and even shot some video inside hog and chicken farms that exposed some shocking video of animal abuse:

"[E]ach year, an estimated 9 billion broiler chickens, 113 million pigs, 33 million cows and 250 million turkeys are raised for our consumption in dark, filthy, pestilent barns," Rolling Stone reported.

As a result of these kinds of exposes, agricultural companies have pushed states such as Iowa, Missouri, and Arkansas to ban the practice of recording undercover video inside factory farms.