People drive and ride amid the smog in Beijing, China, February 14, 2017. REUTERS/Jason Lee

BEIJING (Reuters) - Beijing’s city authorities have taken down from their website a policy document put up just a few days ago that looked to help improve the city’s notorious air quality by banning construction during winter months.

It is unclear if the move means the prohibition is no longer in place, with an official at the Beijing Municipal Commission of Housing and Urban-Rural Development who gave his name as Yu saying the document had been pulled from the website due to misunderstandings over the rules in media reports. He declined to give further details.

The statement, dated Sept. 15, was posted on the commission’s website last Friday, but it was no longer available on Wednesday. It was not clear when it was withdrawn.

Under the plan, all construction of road and water projects, as well as demolition of housing, would be banned from Nov. 15 to March 15 within the city’s six major districts and surrounding suburbs.

As part of dust control measures, the government often instructs construction sites in northern cities to close during bouts of heavy smog in the winter when households crank up heating, drawing on the power grid which is mainly fueled by coal.

Provincial authorities are rushing to enforce the central government’s ambitious targets for preventing toxic air during the upcoming colder months as it has ramped up its years-long war on smog.

The possible pulling of the construction rules underscores the complexity of implementing some of the steps. Among the most stringent measures are orders for heavy industry such as steel mills to curb output by as much as 50 percent during the colder months.

Recent checks of factories across the north have forced many to close or curb operations, roiling supplies of some critical raw materials like coke and coal and sending prices of base metals soaring.