Using its emergency authority, the Drug Enforcement Administration on Tuesday announced a temporary ban of five chemicals used to make synthetic marijuana products, which have grown increasingly popular over the past few years. The ban, which the drug agency said it would pursue in 2010, will remain in effect for at least a year until it is determined whether the chemicals should be permanently controlled. Fake marijuana products produce a high similar to marijuana when smoked. The products  typically sold at smoke shops  have caused numerous health problems including seizures and hallucinations, the drug agency has said.