A staff member works at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the packing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

Staff members work at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

Staff members work at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the packing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the packing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]

A staff member works at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo /Xinhua]

A staff member works at the producing workshop of face mask in a medical devices company in Nan'an District of southwest China's Chongqing, Jan. 27, 2020. In order to ensure the supply of face masks on the market, some mask manufacturers in Chongqing resumed work during the Spring Festival holidays, working overtime to help with the prevention and control of the novel coronavirus. [Photo / Xinhua]