Beijing just issued its first-ever red alert for dangerous smog levels

Beijing has just issued its first-ever red alert for heavy smog - the highest-level emergency response the city can issue to signal a threat to public health.

Around 6:30pm local time on Monday, the Chinese capital's state news agency, Xinhua, informed its citizens that half the city's drivers would be banned from the roadways and that school would be suspended until further notice.

It is the first code red Beijing has issued since the color-coded pollution response system began in 2013.

Pollution levels in China's major cities have been a mounting problem over the last decade, as the country's rapidly growing manufacturing industry races ahead of the government's ability to control emissions, particularly from coal burning.

The result is a constant and ever-expanding cloud of gray that engulfs China's urban areas.

Emergency red alerts are meant to be issued at least 24 hours before the onset of dangerous smog, based on wind and weather forecasts, the New York Times reports.

Smog is considered dangerous depending on its reading in the air quality index. A score above 200 is considered "unhealthy," while a score between 301 and 500 is "hazardous."

On Monday, Beijing's municipal reading was 253.

Here is Xinhua's announcement, with an accompanying photo of the Bird's Nest, Beijing's iconic stadium used during the 2008 Olympics.

The emergency initially began as an orange alert issued on Saturday, the Times reports. An orange alert requires outdoor construction to stop and companies with heavy emissions to quit running.

Red alerts, like the current one, can halt factory production for days on end and close schools, until the skies become clear enough again to lower the threat level.

Smog levels have become so treacherous in China, especially in the northern region, that breathing in a day's worth of polluted air does the equivalent lung damage as smoking 40 cigarettes, or two packs a day.