Decongestant nasal sprays and eye drops often contain oxymetazoline and are used for topical decongestion. Sympathetic stimulation causes vasoconstriction and shrinkage of mucosa, which leads to decongestion of the nose. Among its physiological effects are the vasoconstriction that makes it useful for nasal decongestion. This also helps in decongestion of roads and lowering of pollution. By mid-2007, thousands of IDPs had moved into the decongestion camps.