Summary Box: China mulls microblog limits

CLAMPING DOWN: China is ratcheting up pressure on social media sites that have fast become forums for information and public expression.

WHY IT’S HAPPENING: The Communist Party is preparing for its biggest policy meeting of the year. For a government that is used to controlling what information the public consumes, social media are proving unnerving.

WHAT BLOGS HAVE DONE: Popular microblogs helped mobilize 12,000 people in Dalian to successfully demand the relocation of a petrochemical factory and served as an outlet for public anger after a crash on the showcase high-speed rail system in which at least 40 people died.