When the sun comes up in Beijing on October 1, the Chinese government will aim to celebrate its 70th birthday under a bright blue sky. The Chinese capital will close building sites, reduce the use of fireworks and restrict fuel sales ahead of this year’s National Day. The holiday marks the founding of the People’s Republic of China in 1949. Ahead of major events in the past, officials have taken extreme measures to improve air quality, such as seeding clouds to make rain and closing factories for days. There is still time for the government to announce similar restrictions this year. But business leaders believe widespread closures are not part of the plan, as long as usual smog controls continue to do the job. An independent study last week showed Beijing is set to drop from the list of the world’s top 200 most-polluted cities this year.