VIDEO: There have been numerous fires at the Milwaukee Materials Recovery Facility this year -- so officials with the Milwaukee Fire Department are reminding people that there are things you shouldn't be putting in your blue recycling bin. Officials say people commonly toss items they don't know what to do with into their recycling bin. Some of these items end up posing serious risks to the workers who come into contact with them. "When we think about propane tanks, when we think about pressurized cylinders, they are small bombs. And whether they contain propane, methane, butane or natural gas, under compression, they explode," Milwaukee Fire Chief Mark Rohlfing said. The Milwaukee Materials Recovery Facility is on pace to sort around 68,000 tons of recyclables this year.