A man uses the Nasal Ranger to detect smells in the southern U.S., in this photo provided by St. Croix Sensory. In Denver, the device is being used to monitor complaints of strong marijuana smells. Courtesy of Nasal Ranger hide caption

itoggle caption Courtesy of Nasal Ranger

An ATM sits next to a rack of marijuana clone plants that are used to grow medical marijuana on Wednesday at The Joint, a medical marijuana cooperative in Seattle. Last week Washington became the second U.S. state to adopt rules for the recreational sale of marijuana. Ted S. Warren/AP hide caption

itoggle caption Ted S. Warren/AP

A man smokes marijuana outside Uruguay's parliament in Montevideo on Wednesday, where lawmakers in the lower house debated and passed a bill that would legalize marijuana and regulate its production and distribution. Matilde Campodonico/AP hide caption

itoggle caption Matilde Campodonico/AP