The main factors of ambient air monitoring in Xuchang City were SO 2,NO X,total suspended particulate (TSP),dustfall and sulfation rate during the 9 th Five Year Plan.

• “九五”期间,许昌市环境空气监测主要因子有二氧化硫、氮氧化物、总悬浮颗粒物、降尘和硫酸盐化速率。