At a Glance

China issued its first ever red alert for smog.Some 24 cities have issued red alerts.Hundreds of flights were canceled as a result of the smog.

China issued its first-ever national red alert for severe fog Tuesday after two dozen cities reported persistent air pollution issues.

Theby China's national observatory for parts of the Beijing-Tianjin-Hebei region, as well as in the provinces of Henan, Shandong, Anhui and Jiangsu, according to state news agency Xinhua. A total of 24 cities are currently on red alert for smog, while an additional 21, including Beijing and Tianjin, are listed for an orange alert.

Theas limiting car usage and closing factories to reduce the amount of pollutants entering the atmosphere, according to Reuters.

(MORE:)

A foreign tourist and a child wearing protection masks walk through Tiananmen Square in Beijing as the capital of China is blanked by heavy smog on Wednesday, Jan. 4, 2017.

(AP Photo/Andy Wong)

The regions will experience thick fog, with visibility reduced to less than a third of a mile between Tuesday and Wednesday, the National Meteorological Center reported. Visibility could drop below 200 feet in some of these regions, the center added.

Hundreds of flights have been canceledand many roads were closed because of the smog, Reuters also said.

In 2014, China began a "war on pollution" but continues to struggle in its efforts to tackle the problem.

While this is the first national red alert, it is common for pollution alerts to be issued during the winter months in the northern provinces, which rely on the burning of hundreds of millions of tons of coal each year to heat homes and businesses during China's brutal winters.

MORE ON WEATHER.COM: Beijing China Smog

A woman wears a protection mask as she walks along a street on a polluted day in Beijing, Tuesday, Dec. 8, 2015. Schools closed and rush-hour roads were much quieter than normal as Beijing’s first-ever red alert for smog took effect Tuesday, closing many factories and invoking restrictions to keep half the city’s vehicles off the roads. (AP Photo/Andy Wong)