An index of 10 indicates the highest and most hazardous PM 2.5 concentration. According to the EPA's air quality monitoring network at 10:30 a.m., the PM 2.5 concentrations detected at monitoring stations were at "very high" levels in Tainan, Changhua, Yunlin, Chiayi, Miaoli, and Taoyuan cities and counties, and in the outlying islands of Kinmen and Matsu.
The EPA said concentrations of PM 2.5 in Kinmen and Matsu were very high because of pollutants from outside -- presumably from mainland China, while the high concentration in western Taiwan was due to poor atmospheric circulation and the situation there is expected to improve after rainfalls.
Under Taiwan's 10-tier PM2.5 index, with level 10 (71 痢/cubic meter or above) being the highest, measurements above level 7 (54-58 痢/cubic meter) are deemed severe enough to cause tangible discomfort and health problems.
The EPA said children and the elderly in areas north of Tainan should refrain from outdoor activities and the public are advised to wear masks if they have to go outdoors. (By Yu Hsiao-han and Lilian Wu)