Daily Exposures to Nitrogen Dioxide for Different Groups of Residents in Beijing

In 2006 and 2007, daily exposures to nitrogen dioxide were monitored in four groups of residents, including office workers, schoolchildren, taxi drivers and teachers. A total of 126 24-hour samples of personal NO₂ exposure were collected with passive diffusion samplers. The results show that the average NO₂ exposure is 0.049 mg/m³ overall. 11.9% of samples exceeded the national annual guideline standard, 0.080 mg/m³. Schoolchildren are exposed to the highest personal NO₂ exposure level, and teachers are the lowest, with office workers and taxi drivers in an intermediate position. There is significant difference between schoolchildren and office workers. But the exposure levels changed after adjusted to day-to-day ambient concentrations, which are lowest for teachers, and different from other three groups exposed to a higher level.