Many companies in China have found that good salaries, promotions and career prospects aren't enough — they also need to offer cleaner air within their offices to lure and retain staffers.

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.