Air and water pollution is a bigger concern for Americans than global warming, a Washington Post-Stanford University poll said. A survey last month of 804 adults found just 18 percent named climate change as their top environmental concern, compared to 33 percent in 2007, The Washington Post reported Monday. Global warming is still a concern but air and water pollution ranked higher with 29 percent of those surveyed, the Post said. Seventy-eight percent of those polled say global warming will be a serious problem if left alone and 18 percent say the government is doing enough to solve the problem Democrats voiced greater concern that Republicans and independents, the Post said, with more than half of Democrats concerned global warming will be a \"very serious\" problem if no action is taken, compared to 23 percent of independents. The margin of error for the poll, conducted by telephone June 13-21 was plus or minus 4.5 percentage points.