One problem is what to do with it. Sometimes, landfills are used and wastes are buried. This is commonly done in many parts of the world. If done properly, it is relatively inexpensive. However, poorly designed or managed landfills can create environmental problems. One is litter can attract vermin like rats. Also, wastes may become airborne. Sometimes, pollutants can leach into the water table. As wastes decompose, the methane produced by bacteria smells awful, is a greenhouse gas and may kill the plants growing above the landfill. A sanitary landfill covers the garbage, has a liner to catch materials that leach down and may have a way of utilizing the gas produced to generate electricity. Burning waste creates ash and soot. Incinerators produce pollutants that include dioxins, PAH's, carbon dioxide and others. Recycling of metals, paper, glass and others is a wonderful idea. However, people must be willing to separate their trash to be collected. Biological waste decomposition relies on the natural bacteria and fungi in nature that can digest organic matter and break it down. This material can then be used as mulch or compost to grow crops or for landscaping. There are other methods and associated problems with wastes. As the planet gets more crowded, the 6 billion plus people who reside here are all adding to the problem of waste management.