Shanghai has urged management of tall office buildings to turn off any central air conditioners that are not ventilated, maximize ventilation in offices and implement flexible hours and staggered shifts to prevent the spread of the novel coronavirus.

Many office buildings in the municipality－h(huán)ome to offices of more than 50,000 foreign companies and more than 600 regional headquarters of multinationals－h(huán)ave disinfected their air conditioners, and people have been having their temperatures taken since work resumed last week.

In response, Shanghai Tower, China's tallest building with a capacity of 30,000 people, recently completed the disinfection of its air conditioning ducts and filters and turned on maximum ventilation.

Wang Xuezhi, CEO of Goldhorse, a Shenzhen-based company that helps reduce energy consumption in public buildings, explained that ventilation allows in air from outdoors, keeping the air indoors fresh and preventing the virus from continuously circulating inside.

"Usually, central air conditioning systems on different floors work independently and won't lead to infection across floors," he said.

Feng Kai, an indoor air quality trainer from the China office of the Building Owners and Managers Association, said commercial buildings built in recent years are usually equipped with air filtration layers and sterilizations in their fresh air systems, but the key for building operators is to understand how the heating, ventilation and air conditioning systems work in order to identify air pollution sources and pathways and prevent potential cross-contamination.

Cleaning and sterilization are conducted every 40 minutes in Shanghai Tower, including the lobby, office area, elevators and doorknobs. The frequency of such sterilization at the neighboring 101-story Shanghai World Financial Center and 88-story Jinmao Tower is once an hour.

Shanghai Tower also requested all leaseholders to report the names of people coming into the offices on a daily basis. There are only hundreds of people coming into offices every day－one-tenth the average number－as most people are working from home, according to the building manager.

In Pudong district's Lujiazui central business district, temperature testing of all commuters, the closure of at least half the entries and exits, real-name registration and whole-building disinfection have become standard practices.

Dominic Lau, executive director of the Building Owners and Managers Association of China, said that it had shared a guideline covering the physical environment, air ventilation, protective equipment and cleaning with its more than 70 corporate members on the Chinese mainland and the governments of different levels.

The guideline draws on domestic and foreign experience dealing with public health incidents in the past years, including SARS, H1N1 flu and Ebola.

Lau also suggested more office buildings resort to a unified cleaning team for the whole building, including the areas of the leaseholders, which comprise around 70 percent of a building.

"Only in this way can a unified standard of cleaning be guaranteed, as well as those concerning the management of pests, waste and hazardous materials, which all relate to pandemic control in the building," he said.

Zhu Xiaoming, China representative of Dr. Becher, a German company specializing in detergents, reminded property managers of scientific sterilization to be careful with corrosive and flammable disinfectants.

"People should be kept away when air disinfection is conducted," he said.