GAW Report No. 205 - IGAC Project

CHAPTER 3 - ASIAnearly half of the C1–C3 aldehydes were attributed to secondary sources, while regionalbackground accounted for 21-23% of the mixing ratios of aldehydes. Primary anthropogenicemissions contribution to aldehydes was comparable to biogenic emissions contributions (10–16%)[Liu et al, 2009].Data available on air pollutantsThe air quality in Beijing is routinely measured by Beijing Municipal EnvironmentalProtection Monitoring center. The center runs 27 automatic monitoring stations with 13 stations inthe urban center and 14 stations in sub-urban regions. The air pollutants measured at thesestations are ambient concentrations of SO 2 , NO 2 , and PM 10 . The monitoring data are available viaBeijing Municipal EPB.From 2006, the air chemistry in Beijing city and surrounding areas were studied in theCareBeijing field campaigns. More species including O 3 , PM 2.5 , CO, volatile organic compounds(including carbonyls), HONO, and size distributions and chemical compositions of particles weremeasured. A database for CareBeijing-2006, 2007, and 2008 was established and assessablebased on the data protocol of the project.The status and trend of the pollutionThe trends of the concentrations of SO 2 , NO 2 , CO, and PM 10 were evaluated based on theannual communiqué released by Beijing Municipal Environmental Protection Bureau from 1999 to2007 (Figure 9). The SO 2 levels have been decreasing and went below the national ambient airquality standard (NAAQS) for SO 2 at grade II in 2005. The annual average NO 2 concentration hasstayed at a level of about 70 µg/m 3 and almost remained constant. PM 10 is reported to be the majorair pollutant on about 90% of the days in the last nine years in Beijing and its annual averageconcentrations were all above the NAAQS for PM 10 from 1999 to 2007. On 30% of the days eachyear, the daily average PM 10 concentration exceeded the Grade-II standard of 150 µg/m 3 .Figure 9 - The change of annual average concentrations of SO2, NO2, CO, and PM10 in Beijing between 1999 and 2007[Beijing Municipal Environmental Protection Bureau, The communiqué on the Environmental Status ofBeijing City, 1999 ~ 2007]The air quality is assessed by an Air Pollution Index (API) that reflects the concentrations ofthree pollutants; SO 2 , NO 2 , and PM 10 . However, the secondary air pollutants cause more significantadverse effects on public health and eco-systems. From a recent evaluation of air quality in Beijing[Tang et al., 2009], NO X concentrations decreased linearly at a rate of 3.9±0.5 ppbv/yr after 2002,70