Maine is opposing the construction of a cement plant in upstate New York. Critics said the plant will emit 20 million pounds of air pollutants each year that will make their way to Maine. State environmental officials are scheduled to meet Monday to determine how to respond to the proposed coal-fired Saint Lawrence Cement plant. The plant is proposed for the east bank of the Hudson River south of Albany. James Brooks is director of the Bureau of Air Quality at the Maine Department of Environmental Protection. He said the state has the option to become an intervenor, which would allow officials to participate in hearings in New York. The proposed facility would replace a 40-year-old plant in Catskill.