Extreme smog with concentrations of dusty particles more than ten times over the official limits has forced authorities in Beijing to restrict traffic and factory operations.
The red alert – the most serious state on a four-level scale - was announced on Monday as severe air pollution is expected to linger for at least the next three days. Concentration of the so-called PM2.5 particles has reached 300 micrograms per cubic metre. The World Health Organisation considers 25 micrograms safe for human health.
Blamed mostly on coal-fired power plants, construction work, factory emissions and transport, the current spell is the first one that triggered the red alert since China put a new warning system in place.
The Beijing Municipal Environmental Protection Bureau advised schools to close and put restrictions in place that only allow drivers to use their cars every second day based on the last digit of their licence plates.
The city of 22.5 million people is trying to ease the situation by adding extra buses and subway trains to help people move around.
Struggling with severe air pollution on a regular basis, Beijing was covered in thick smog for most of November due to unusually cold weather. Although there have been stretches of severe smog previously that lasted for more than three consecutive days, these spells were originally forecast to ease in a shorter period of time, hence no red alert was issued.
The alert requires a forecast of more than 72 straight hours with PM2.5 levels of 200 micrograms per cubic metre or more. It has been reported previously that air quality in Beijing has improved in the first ten months of 2015.
The country has tightened its emission standards and started making investment into renewable energy generation. However, it still relies on coal-fired power plants for more than 60 per cent of its electricity.
China, the world's biggest carbon emitter, plans to upgrade coal power plants over the next five years to tackle the problem and says its emissions will peak by around 2030 before starting to decline.
According to a study by researchers from Germany’s Max Planck Institute published in the journal Nature this year, 1.4 million people die prematurely in China each year because of pollution.