Cross-sectional studies have been conducted to compare 76 switchboard workers and 34 individuals as control in Vietnam Post and Telecommunication Group. The study results show that there was statistically significant decrease on some indicators of the EEG of switchboard workers before compared to after working cases. Alpha wave amplitude from 27.83 + or - 5.80 uV downed to 24.93 + or - 6.55 uV
Alpha wave index from 56.86 + or - 11.45 percent decreased to 49.61 + or - 11.60 percent, Alpha waves extinguish time from 0.051 + or - 0.011 s prolonged to 0.074 + or - 0,012 s
Alpha waves recovery time from 0.38 + or - 0.008 s extended to 0,55 + or - 0.011 s. Results of study clearly showed the worn-out status of workers of switchboard workers in working cases.