台灣地區近五年臭氧污染現況的統計與事件分析

Abstract

台灣地區空氣品質不良（空氣污染指標(PSI)＞100）的主要指標污染物種為懸浮微粒(PM10)與臭氧，但臭氧濃度與其前驅物之間並不存在線性比例的削減管制關係，使得近年來臭氧的防制效果並不佳，就未來欲達成台灣地區空氣品質之改善，臭氧問題將是重要的關鍵。 本研究利用2000年~2004年空氣品質監測站的監測資料，將臭氧及潛勢臭氧(O3+NO2)、臭氧前驅物非甲烷碳氫化合物(NMHC)及氮氧化物(NOx)之監測值予以分析，以濃度時間序列，地理空間分佈，解析易發生臭氧及O3+NO2之高污染的區域、季節、時段及污染趨勢，並探討其發生原因，以期對臭氧污染防制能有所貢獻。另外分析大氣通風指數，了解台灣氣候變遷情況，並藉由通風指數及污染物濃度之間的特徵值關係，建立一個定性的評估指標來推估污染物排放量的增加或減少的趨勢，以利執行目標區域的減量策略。 研究結果顯示台灣地區臭氧污染逐年惡化，且污染區域也有擴大現象，特別是中部地區臭氧污染明顯的惡化，而潛勢臭氧(O3+NO2)濃度亦是逐年增加，尤以南部地區更為明顯，所以中南部地區臭氧污染甚為嚴重。 高濃度O3+NO2易發生的地區都是主要工業區、都會區及交通要道的排放源，反而發生臭氧高濃度的地區大多屬於都市周邊地，甚或十分偏遠的測站。至於容易發生臭氧污染嚴重的季節，北部地區是春夏兩季，中部是秋春兩季；而南部則是在秋季最易發生，其主要發生時段，北部地區以12、13點最早，南部地區在13、14點，而中部地區較晚在14、15點。通風指數歷年來一直都有增加的趨勢，表示大氣擴散能力良好，空氣污染物不易累積，特別是中部地區通風指數上升幅度為最大。 臭氧前驅物氮氧化物(NOx)的濃度是逐年遞減的，而非甲烷碳氫化合物(NMHC)濃度則是逐年遞增；定性排放量指標推估結果，NMHC、NOx、CO、PM10等污染物，歷年排放量都是遞增的，與TEDS推估排放量遞增趨勢吻合，可見要管制臭氧污染的策略，對臭氧前驅物尚有很大的努力空間。

The major pollutants caused PSI greater than 100 were PM10 and ozone in Taiwan. The relationship between concentration of ozone and ozone precursor was not linear, and reducing the precursor couldn’t be helpful for the reduction of ozone. How to control the amount of ozone was important for the air quality in Taiwan. This research used the database from 2000 to 2004 of air quality monitoring station to analyze the value of ozone, potential ozone(O3 and NO2) and ozone precursor(NMHC and NOx). By concentration-time series method and geographic space distribution to understand why the concentration of ozone and potential ozone were high in some region and time period. Furthermore, this research established a qualitative assessment index to estimate the trend of emission of pollutants with the characteristic value relation between ventilate index and concentration of pollutants. The result showed that ozone pollution in Taiwan was more and more serious, and the regions in which ozone pollution happened were enlarged. The most obviously serious region was central Taiwan, while the concentration of potential ozone was much higher in southern Taiwan. The situation of high potential ozone concentration always happened in industrial regions, cities, and vital communication lines. But the regions in which high ozone concentration happened were always near cities or the remote monitoring stations. So far as seasons were concerned, the most serious ozone pollution happened in spring and summer for northern Taiwan, in fall and spring for central Taiwan, and in fall for southern Taiwan. However, in order of time period at which the serious ozone pollution happened was 12:00 and 1:00 p.m. for northern Taiwan, 1:00 and 2:00 p.m. for southern Taiwan, and 2:00 and 3:00 p.m. for central Taiwan. When ventilate index increased, it meant that the atmospheric diffusion was better so that air pollutants wouldn’t accumulate. And the ventilate index of central Taiwan increased much greater. From this research, the concentration of ozone precursor- NOx decreased year by year, but NMHC increased. And the result of qualitative assessment index showed that the emission of NHMC, NOx, CO, and PM10 increased yearly and which was identical with the estimation of TEDS. Therefore, control the amount of ozone precursor would be implemental for the control of ozone.