Pollution in Shenyang, Liaoning province. Photo: Reuters/Stringer

Northern China continues to labor under stifling pollution that has persisted for almost a week. Flights, traffic and shipping have been disrupted, schools and factories have been closed, and residents have expressed dissatisfaction at the efficacy of anti-smog measures.

More than two dozen cities have issued pollution red alerts, which are issued when the AQI (air quality index) 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.

On Wednesday, concentrations of hazardous breathable particles known as PM2.5 were at a dangerous 360 micrograms per cubic metre in Beijing, according to official data. The safe recommended level of PM2.5 is 10 micrograms, according to the World Health Organization.

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.

As the haze has thickened, impacting everyday life, it has been reported that “smog refugees” are attempting to evacuate. Ctrip, China’s leading online travel agent, has said it expects 150,000 people to flee the smog by traveling to places like Australia, Indonesia, Japan and the Maldives.