American health care company 3M's Shanghai factory has been busy with production recently due to the rapid spike in demand for masks in China due to the novel coronavirus that recently appeared in Wuhan.

3M is popular in China for anti-pollution masks. As the novel coronavirus spreads, 3M sold out of masks on its official online stores on e-commerce platforms Taobao and JD.com as of Wednesday afternoon. 

Mask prices also went up from three yuan to as much as 40 yuan (seven U.S. dollars) each.

A staff member from the 3M Shanghai factory told China's business media Yicai that the factory is out of stock, and they are "working overtime to produce mask products."

"Some workers will return to their hometown on Spring Festival, and some will stay in the factory to work," said the staff member. "The factory's production will not stop (during Spring Festival)."

Read more: Battling the novel coronavirus: What we know so far