1120 GMT May 25, 2019
Residents in Shijiazhuang, the capital of heavily industrialized Hebei Province that surrounds Beijing, complained that schools were still open even though the city remained on red alert with air pollution levels close to record highs, according to Reuters.
Media reports in central China's Henan Province also 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 windows are sealed shut and they don't dare to ventilate and visibility is at just 20 meters," the post said on Wednesday.
China began a 'war on pollution' in 2014 amid concern its heavy industrial past was tarnishing its global reputation and holding back its future development. However, it has struggled to reverse the damage done by decades of breakneck economic growth, much of it based on the coal-burning power sector.
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, another pollution gauge, were at a dangerous 380 micrograms per cubic meter. PM2.5 levels also remained high in Beijing, with average readings of 360 micrograms per cubic meter, according to official data. The safe recommended level of PM2.5 is 10 micrograms per cubic meter, according to the World Health Organization.