ADD AIR pollution to the list of challenges that China’s new leadership must address to satisfy its increasingly restless citizenry. Over the weekend, Beijing and more than 30 other cities were enveloped by a thick haze. Measurements of hazardous particles spiked to unprecedented levels — and so did complaints on the country’s social media. On Monday, the government’s principal propaganda organs essentially surrendered to public sentiment, breaking their silence and publishing a host of articles and editorials calling the pollution “choking, dirty and poisonous,” among other things.

The state organs were only stating the obvious. According to readings by the U.S. Embassy, the air quality in central Beijing on Saturday, based on a measure of hazardous particulates, stood at 755 on a scale of 0 to 500. According to the U.S. Environmental Protection Agency, a level above 300 is “hazardous;” according to the World Health Organization, a reading of 500 means the particulate level is 20 times that considered safe. By way of comparison, the level in Washington on Wednesday peaked at 39.

Still, the relative openness of the official media was a change from past practice. Up until a year ago, the U.S. Embassy, which began reporting air pollution levels in 2008, was the only public source of such information — and Chinese authorities repeatedly demanded that the embassy stop releasing the numbers, most recently last June. The State Department’s creditable refusal to comply helped raise awareness of the pollution problem and eventually prompted authorities to begin releasing their own numbers.

The Chinese government is not ignoring the pollution problem. Having spent billions in an attempt to clear the skies over Beijing before the 2008 Olympics, authorities are now spending billions more to replace the capital’s coal-fired power stations — a major source of the pollution — with cleaner gas-fired plants by 2015. They are also trying to push older cars and trucks off the city’s clogged streets.

Nevertheless, the high readings recorded in recent days underline that the continuing push for rapid economic growth is creating problems — from pollution to growing inequality and massive official corruption — that are fueling discontent, especially among the country’s growing urban middle class. Last week, China’s microblogs pulsed with outrage over the censorship of a weekly newspaper that attempted to publish an editorial supporting adherence to the constitution. Now they are echoing with complaints over the pollution emergency and the policies that caused it.

China’s outgoing cohort of leaders, led by Hu Jintao, responded to the discontent by trying to suppress it. But it’s becoming clear that that strategy will not work for their successors, under Xi Jinping. Mr. Xi’s regime will have to face the underlying problems or risk a crisis in Beijing much greater than any spike in air pollution.