The Lishui Bridge in Chaoyang District, Beijing in heavy fog on November 14, 2018. (Photo: VCG)

The Central Meteorological Observatory issued a yellow alert for smog in the Beijing area on Tuesday.

Pedestrians walk in heavy fog in Beijing. (Photo: VCG)

It was estimated that from Tuesday evening to Wednesday morning, the Beijing-Tianjin-Hebei region will have heavy smog. Some areas in Beijing will have extremely thick smog with visibility less than 50 meters.

The Beijing Municipal Environmental Monitoring Center on Wednesday characterized the air pollution level as heavily polluted. 

(Graphic: Wang Zi and Zhan Huilan)

This is the first yellow alert for air pollution since a new plan released in September aimed to reduce the average intensity of PM2.5 by around 3 percent year-on-year in Beijing, Tianjin, Hebei and surrounding areas from by March 2019.

The CBD area in Beijing in heavy fog on November 14, 2018. (Photo: Chi Jingyi/People's Daily app)

The CBD area in Beijing in sunny day in October, 2018. (Photo: Chi Jingyi/People's Daily app)

The plan was released by the Ministry of Ecology and Environment, several other central government departments and the governments of six provincial-level regions.

A total of 3.62 million additional households in Beijing, Tianjin and 26 other cities in nearby regions will have had their coal-fired heating systems converted by the end of October 2018, the plan noted, citing data included in local government plans.