Matt Damon battled disgusting conditions while shooting his new movie Elysium in the world's largest garbage dump as the actor was breathing in dust formed from faeces. The Bourne Identity star leads the cast of South African director Neill Blomkamp's new sci-fi film, set on a ravaged future Earth, which features scenes shot on location at a huge landfill site in Mexico. Damon has revealed members of the film crew wore gas masks to protect themselves from a fetid dust which swirled around the site, but the actors had to breath the foul air. He says, "(It was) the toughest two weeks of shooting I've ever had... (We had to) literally eat s**t... It was explained to us that, like any dump anywhere in the world, the dust is actually comprised largely of faecal matter. After they tell you that the dust is all faecal matter, then they see what you're doing (on set), they go, 'You know, not your dust... all the other dust!' So, at the end of every day, as we'd wipe this stuff off, we'd be basically throwing these s**tty towels at each other." Damon admits the cast and crew saw the funny side of the situation, adding, "For instance one of (the locations) was called Poo River. Literally, that was, 'OK, can we get everybody down to Poo River for scene 36?'" However, the star insists the tough shoot was worth it: "Neill just said, 'Look, I know I can do a lot with a green screen... but I've never seen a giant set-piece in a sci-fi film in a setting like that'. Everybody on the crew recognised that it was a really good idea and it was going to be worth it. It's really one of the best sequences in the movie and I'm really proud of it."