HANGHAI (Reuters) – Shanxi province, China’s biggest coal producing region, has ordered local governments to further restrict industrial activity beginning on Saturday to curb winter smog, it said in a notice on Thursday.

Smog billows from chimneys and cooling towers of a steel plant during hazy weather in Taiyuan, Shanxi province, China, December 28, 2016.

The province said local governments must “strictly implement” emergency emission cutting measures and impose limits on industrial output and freight beginning on Nov. 4 after forecasters predicted a bout of unfavorable weather.

Shanxi originally planned to begin reducing industrial activity in major cities once the winter heating period started in mid-November. The sectors affected include coking coal, aluminum, steel and ceramics.

To meet 2017 air quality targets, China announced in August that 28 cities throughout northern China would cut small, breathable particles known as particulate matter 2.5 (PM2.5) by at least 15 percent over the October 2017 to March 2018 period.

Shanxi province is located southwest of the capital of Beijing and borders Hebei province.