However,the WBGT value was calculated as the average WBGT is found to be between 29.7-32.5 °C, which is well below the benchmark by the Ministry of Industry in 2546 (2003) on measures to protect the safety of the operation of the plant. The working group on environment in one heat and standard of the Regulation of the Ministry of Labour, B.E. 2549 (2006) that limit Wet Bulb Globe Temperature of workload is light not over than 34 °C.