Hundreds of NATO peacekeepers wearing surgical masks shut down a lead smelter in Kosovo yesterday, citing environmental dangers caused by its emissions, which have been measured at levels 200 times those accepted by the World Health Organization. A number of outraged local residents threw rocks and sticks at the troops to protest the closing of a facility, which is part of a mining complex that many locals see as vital to Kosovo’s economy. The troops used tear gas and rubber bullets to disperse the protestors. Kosovo’s top UN administrator, Bernard Kouchner, defended the shutdown, saying 160 people in the area have been hospitalized in the past year because of lead poisoning.