A billboard blocks the view to a construction site against the backdrop of a polluted skyline in Beijing, Thursday, Dec. 27, 2007. Beijing is usually shrouded under a blanket of gray pollution. As a cover-up during the Olympics, city officials have tried to add some color. But it's mostly artificial, shades of blue and green coming from enormous murals and posters, many showing off palm trees and blue skies erected like Hollywood sets to hide the reality of the Chinese capital.