BEIJING/SINGAPORE (Reuters) - Nearly 300 million people have gone back to work in China since the Lunar New Year break as more companies restart business and coronavirus travel restrictions ease, although many small firms are still struggling to find enough workers to run plants.

A woman wearing face mask is seen on a subway as the country is hit by an outbreak of the novel coronavirus, in Shanghai, China March 2, 2020. REUTERS/Aly Song

Eighteen regions in mainland China have cut the emergency response level as of Monday, and authorities eased travel restrictions amid a sharp drop in new coronavirus infection cases.

The flu-like epidemic has killed 2,912 people and infected more than 80,000 across the country.

China transportation ministry data showed an average of 15.8 million passengers returned from their hometowns per day last week, the third week after the prolonged Lunar New Year break.

That brings the total to 295 million people so far tracked by the ministry as having returned to their workplaces since the holiday, according to Reuters calculations based on transportation ministry data.

(Graphic: China's February travel flows: )

Increasing traffic flows in big cities also indicate more commuting across the country.

Location technology firm TOMTOM’s traffic index shows congestion levels picked up noticeably in most major cities on Monday to their highest levels since the virus outbreak.

(Graphic: Traffic congestion levels rise in China: )

Public transportation systems have also gotten busier. Of the 33 Chinese cities that have metro lines, only three have system restrictions still in place: Wuhan where the virus originated, Wenzhou in manufacturing hub Zhejiang province, and Urumqi in northwestern Xinjiang.

Average daily passenger volumes at metros across the country reached 10.2 million last week, up 65.15% from a week earlier, according to data compiled by China Association of Metros.

(Graphic: China's metro passenger flows: )

But air quality measures indicate China’s industrial emissions remain well below normal.

Pollution data monitored by NASA and European Space Agency satellites show that the mean density of nitrogen dioxide - a noxious gas emitted by motor vehicles, power plants and industrial facilities - dropped significantly during February 10-25, to mostly below 125 micromoles per square metre in northern and eastern China.

That compares to more than 200 micromoles in Jan 1-20, according to maps from NASA’s Earth Observatory. The drop in readings suggests a greatly curbed industrial engine as the virus-led travel restrictions took hold.

“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” said Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Centre in a statement on Earth Observatory.

(Graphic: NASA satellites data on nitrogen dioxide emission over China: )

Underscoring the suddenness of the economic downshift, the Caixin/Markit Manufacturing Purchasing Managers’ Index (PMI) tumbled to 40.3 last month, the lowest on record, down sharply from 51.1 in January as well as the 50-mark that separates growth from contraction.

Daily coal consumption at six major coal-fired power groups across China is now starting to pick up, however, with 450,700 tonnes consumed on Monday, the highest level in five weeks.

(Graphic: China coal use and stocks March 2, 2020: )

China’s top officials have urged local authorities to do everything they can to help companies resume production, including extending cheap loans and simplifying paperwork.

According to Chinese authorities, at least 11 regions in mainland China have seen resumption rates at companies with annual revenue above 200 million yuan ($28.73 million) exceed 90%.

(Graphic: Work resumption rates at firms across mainland China: )

But the matrix doesn’t specify the utilisation rates at the firms, and excludes small-sized enterprises.

A "nightlight" index launched by China Merchants Bank 600036.SS, based on light intensity at a sample of 143 industrial parks across the country at night, shows that work resumption levels remain below 55% as of Feb.28, compared to a peak of more than 80% in late last year.

(Graphic: China Merchant Bank night lights resumption index at industrial parks: )

Ping An Bank 000001.SZ estimated that average capacity resumption at its 600 small- and micro-businesses (SMEs) clients was 59% as of Feb.24, up from 30% in the prior week.

A survey of 577 companies in China by the European Union Chamber of Commerce and the German Chamber of Commerce found almost half reporting staff shortages and almost a third struggling with compliance requirements.