A permit has been granted by environmental regulators, paving the way for construction of the nation’s largest cement plant south of St. Louis in Ste. Genevieve County. Plans by Holcim, a Swiss-based company, to build the plant on the banks of the Mississippi River have become a lightning rod of controversy for environmentalist who fear the plant will belch pollution and undermine efforts to clean-up St. Louis’ air. The State Department of Natural Resources requires Holcim to restrict nitrogen oxide emissions. The company plans to use experimental technology to comply. It has seven years to prove it works. The plant will eventually employ 200 people. About one-thousand workers will help with construction of the plant.