Workers install a new clean air system in J.D. Power's office in Shanghai, December 20, 2015. [Photo/Agencies]

BEIJING - It's not only about salaries, promotions and career prospects - many companies in China have found they need to offer cleaner air within their offices to lure and retain staff.

Air quality has deteriorated badly in China's north and east, including in Beijing and Shanghai. Companies, especially multinationals, based in these cities are spending tens of thousands of dollars to install air filtration systems and real-time pollution monitoring devices in their offices.

International market research company J.D. Power has installed new clean air systems at its Beijing and Shanghai offices, an executive said. Auditing firm Pricewaterhouse Coopers and British advertising firm WPP Plc are doing the same in their premises.

"If a company is willing to reduce pollution inside, it shows it is responsible and will have good growth," said Shanghai resident Yao Hui, who has decided to leave a Chinese furniture company where she has worked for four months after finding its office had the highest category of pollution on a measurement device she used.

"I'd still have to look for something in marketing, but a clean air environment is an important factor," said the 24-year-old marketing professional.

Staff turnover rates are relatively high for multinationals based in China, and air pollution has been cited as the top challenge in luring and retaining talent among such companies, according to the latest business confidence survey by the European Chamber of Commerce.

The screen on a mobile phone displays an air quality reading as workers install a new clean air system in J.D. Power's office in Shanghai, December 20, 2015. [Photo/Agencies]