A worker produces medical masks at Liaoning Shengjingtang Biotechnology Co., Ltd in Shenyang, capital of northeast China's Liaoning Province, April 14, 2020. The company has been actively manufacturing medical masks that will be exported overseas. (Xinhua/Yang Qing)

Workers produce medical masks at Liaoning Shengjingtang Biotechnology Co., Ltd in Shenyang, capital of northeast China's Liaoning Province, April 14, 2020. The company has been actively manufacturing medical masks that will be exported overseas. (Xinhua/Yang Qing)

A staff member checks stockpile of medical masks at Liaoning Shengjingtang Biotechnology Co., Ltd in Shenyang, capital of northeast China's Liaoning Province, April 14, 2020. The company has been actively manufacturing medical masks that will be exported overseas. (Xinhua/Yang Qing)

A worker produces a medical mask at Liaoning Shengjingtang Biotechnology Co., Ltd in Shenyang, capital of northeast China's Liaoning Province, April 14, 2020. The company has been actively manufacturing medical masks that will be exported overseas. (Xinhua/Yang Qing)

Workers produce medical masks at Liaoning Shengjingtang Biotechnology Co., Ltd in Shenyang, capital of northeast China's Liaoning Province, April 14, 2020. The company has been actively manufacturing medical masks that will be exported overseas. (Xinhua/Yang Qing)

Workers produce medical masks at Liaoning Shengjingtang Biotechnology Co., Ltd in Shenyang, capital of northeast China's Liaoning Province, April 14, 2020. The company has been actively manufacturing medical masks that will be exported overseas. (Xinhua/Yang Qing)