Hundreds of government inspectors patrolled Beijing on Wednesday to enforce temporary bans on barbecues and make sure that cars with even number plates were the only ones on the roads. Many Beijing highrises simply disappeared into the grey haze, as commuters wearing face masks headed to work. Emergency closures of power plants, steel mills and ports to reduce the pollution are expected to pressure coal prices. China is the world's biggest consumer of coal and winter is peak demand season. Twenty four cities had issued red alerts for dangerously high pollution as of Tuesday. Residents in Shijiazhuang in Hebei province complained that schools there were open even though the city remained on red alert, and media reports in central China's Henan province carried images of students taking exams in the smoggy open air. 'We already don't know how long this smog will last, so why aren't classes being stopped?' a Shijiazhuang resident posted on China's Twitter-like Weibo microblogging service. 'The students are wearing masks every day and attending class in a daze,' the post said on Wednesday. Shijiazhuang's education authority issued a notice on Monday saying all classes would be suspended. The air quality index (AQI) in the major steel-producing district of Fengnan in the Hebei city of Tangshan was still as high as 578 on Wednesday morning. Red alerts are issued when the AQI is forecast to exceed 200 for more than four days in a row, 300 for more than two days or 500 for at least 24 hours. Concentrations of hazardous breathable particles known as PM2.5 were also at a dangerous 360 micrograms per cubic metre in Beijing on Wednesday, according to official data. The safe recommended level of PM2.5 is 10 micrograms, according to the World Health Organisation. The Beijing-Tianjin-Hebei region, known as Jing-Jin-Ji, has been at the forefront of China's efforts to cut pollution and has pledged to cut emissions of PM2.5 by 25 percent over the 2013-2017 period. Guo Jinlong, Beijing's top Communist Party official, said at a Tuesday meeting that the winter smog could make it harder for the region to meet annual targets. Pollution battle complex Guo said more work was required to ensure emergency measures were fully implemented, according to an account of the meeting released by the Ministry of Environmental Protection (MEP). China began a 'war on pollution' in 2014 amid concerns its heavy industrial past was tarnishing its global reputation and holding back its future development. But Environment Minister Chen Jining told the Tuesday meeting that the mix of industries and energy types throughout northern China made pollution a complex, long-term challenge, and clean-up efforts still lacked strength and focus. 'China's long-term clean air vision requires the cleaning up of both the industrial structure and energy structure,' said Tonny Xie, director of the Clean Air Alliance of China. 'The effect will be very limited if we only focus on the short-term emergency measures.' PM2.5 emissions in Jing-Jin-Ji and surrounding regions fell more than 14 percent in the first 10 months of 2016, but Xie said the state needed to deploy a 'special control strategy' during winter, when surging coal use and unfavourable weather routinely causes smog. The ministry has been naming and shaming companies for failing to cut output during bouts of smog, and it has also accused local authorities of monitoring lapses. Many citizens have been blaming lax enforcement in other regions, including Shanxi and Inner Mongolia, China's two biggest coal producers, though researchers said on Wednesday that the bulk of pollution sources remained local. 'Air quality in the Beijing-Tianjin-Hebei region is influenced by pollution from Shanxi, Inner Mongolia, Shandong, and Henan and that's why the State Council (China's cabinet) has been coordinating all these provinces,' said Xie. 'Emission control standards should be equally implemented in those regions to avoid the relocation of pollution,' he added.