| Title: | "A study of ground-level ozone pollution, ozone precursors and subtropical meteorological conditions in central Taiwan" |
| Author(s): | Tsai DH; Wang JL; Wang CH; Chan CC; |
| Address: | "Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, No. 17, Xu-Zhou Rd., Taipei 100, Taiwan" |
| ISSN/ISBN: | 1464-0325 (Print) 1464-0325 (Linking) |
| Abstract: | "Hourly concentrations of ozone (O(3)), 55 volatile organic compounds (VOCs, ozone precursors) and nitrogen oxides (NOx) were measured at an upwind urban site, a downwind suburban site, and a rural site in central Taiwan, from January 2003 to December 2006. VOC and NOx mean concentrations showed a gradient from high to low across the urban (56 ppb and 34 ppb), suburban (38 ppb and 27 ppb) and rural sites (25 ppb and 21 ppb) but a reverse gradient in ozone across these sites (24, 27, and 29 ppb, respectively). Although there was about twice the difference in VOC concentrations between the urban and rural sites, nearly 65% ozone formation potential was contributed to by the same 9 VOCs. Seasonal patterns showed peak ozone levels in autumn and minima in summer at the urban site, but minima in winter at the downwind suburban and rural sites. Ozone precursor levels, on the other hand, were lowest in summer and highest in winter. The diurnal pattern showed that ozone levels peaked one hour later at the rural site than at the urban site. The ethylbenzene to m,p-xylene ratio, an indicator of the age of the air mass, increased from 0.4 at the urban site to 0.6 at the suburban site and 0.8 at the rural site during daily peak ozone times. This finding suggests the transport of ozone and precursors from upwind to downwind producing elevated ozone levels in the suburban and rural areas. Ozone episodes occurred mostly in days with a mean midday UV index of 6.5 (1 UV index=100 J m(-2)) and wind speed at 1.3 m s(-1) at all three sites" |
| Keywords: | "Air Pollutants/*analysis Air Pollution/analysis Environmental Monitoring Hydrocarbons/*analysis Nitrogen Oxides/*analysis Oxidants, Photochemical/*analysis Ozone/*analysis Seasons Sunlight Taiwan Tropical Climate Vehicle Emissions Wind;" |
| Notes: | "MedlineTsai, Dai-Hua Wang, Jia-Lin Wang, Chieh-Heng Chan, Chang-Chuan eng Research Support, Non-U.S. Gov't England 2008/01/05 J Environ Monit. 2008 Jan; 10(1):109-18. doi: 10.1039/b714479b. Epub 2007 Nov 23" |
