Air quality is the second biggest concern for companies renting offices in Beijing, although the capital remains their primary location for regional or national headquarters, research showed on Wednesday.

About 66 percent of respondents identified air pollution as a key disadvantage for Beijing as an office location, second only to rising rents, according to international real estate service provider CBRE.

Sixty-eight percent of the respondents believed that "air pollution threatens employees' health and work efficiency". In addition, 60 percent said that "air pollution has made senior expatriates less willing to work in Beijing". A further 29 percent said that air pollution has "a significant impact".