| This paper deals with 3-years investigative results of 37 underground installations in Changsha, Wuhan, Beijing, Shengyang and Dailian cities. The results show that as the installations have been in use, mean concentration of air anions is 201/cm3, much lower than that at ordinary rooms, while mono-polarity index are 2.0, much higher. The main factors affecting air anions are radon and its daughter, dust and air humidity, ventilating conditions etc. It has been determined that concentration of radon daughter in the air is 93 Bq/m3. In this paper, the method for estimating radon exhalation rate, radon proof ventilation rate and effective way for improving air anions have been discussed. |
