Several parts of southern China are experiencing heavy smog. The national observatory has issued a yellow alert for air pollution. Weather authorities say heavy smog will linger in provinces in the southwest, southeast, and some parts of central China. The country has adopted various measures over the years to reduce the blanket of smog that shrouds many of the country's northern cities, but now the problem has extended to the south. 

Cities across China's south are on alert for the smoggy conditions.

Local authorities have implemented traffic controls on multiple expressways due to the smoggy conditions.

"(The traffic) leads to a lot of wasted fuel, which increases the cost of driving," said Zhang Yixin, driver of Jiangxi.

Some places with the worst of the smog had visibility of under 20 meters, or less than 70 feet.

In Shanghai, the heavy smog has even created a new job for hired photographers -- replace the sky color from gray to blue.

"It brings us more business. In winter, the smog is so much greater than before," said a photographer in Shanghai.

In southwestern China's Sichuan province, more than 20-thousand people were stuck at the Chengdu local airport. Flights had been grounded for at least 10 hours because of the smog.

It is said to be the worst fog to hit the city in years.

Experts say the air pollution was aggravated by polluters that are moving from North to South.

In response, people are trying to find ideas to reduce urban smog – for example, the invention of massive water sprayers to grab dirt from the air but that have proved ineffective.

China has set a target of reducing smog and ensure “good air quality” for 80 percent of the year. But weather authorities say smog levels are increasing.

It is hoped that officials can find better solutions, before the smog continues to spread.