Yes, the government have ordered many factories, not only in North China, to halt production, due to pollution levels. This is especially true in metal fabrication, electroplating, fabric dyeing and many other trades that use chemicals as part of the manufacture or finishing processes.
These restrictions all have a knock on affect within the supply chain for the final product.
The time limits are open ended and do not have an "end date", until the government lifts the ban, which could be a month, a year or even closing a manufacturing plant (or thousands) down completely.
Different areas in China will have different limits imposed, so the option is to find alternative suppliers in a different area, which is easier said than done.
China (believe it or not) are very pro active when it comes to cutting down pollution levels. Heavy fines are imposed on factories, or are closed down for non compliance.
This has been in effect for the past 18 months and is spreading to many trades.
Some suppliers will not tell you the whole truth for fear you will cancel and move to find alternative suppliers.