Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 43 12 2014 12 15 1635 9 Kwang Rae Cho Dept. of Anesthesiology and Pain Medicine, Busan Paik Hospital, Inje University, Busan, South Korea. Myoung-Hun Kim Dept. of Anesthesiology and Pain Medicine, Busan Paik Hospital, Inje University, Busan, South Korea. Myoung Jin Ko Dept. of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University, Busan, South Korea. Jae Wook Jung Dept. of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University, Busan, South Korea. Ki Hwa Lee Dept. of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University, Busan, South Korea. Yei-Heum Park Dept. of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University, Busan, South Korea. Yong Han Kim Dept. of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University, Busan, South Korea. Ki Hoon Kim Dept. of Surgery, Haeundae Paik Hospital, Inje University, Busan, South Korea. Jin Soo Kim Dept. of Surgery, Haeundae Paik Hospital, Inje University, Busan, South Korea. 2015 10 15 Hypothermia generates potentially severe complications in operating or recovery room. Forced air warmer is effective to maintain body temperature. Extremely low frequency electromagnetic field (ELF-EMF) is harmful to human body and mainly produced by electronic equipment including convective air warming system. We investigated ELF-EMF from convective air warming device on various temperature selection and distance for guideline to protect medical personnel and patients.The intensity of ELF-EMF was measured as two-second interval for five minutes on various distance (0.1, 0.2, 0.3, 0.5 and 1meter) and temperature selection (high, medium, low and ambient). All of electrical devices were off including lamp, computer and air conditioner. Groups were compared using one-way ANOVA. P<0.05 was considered significant.Mean values of ELF-EMF on the distance of 30 cm were 18.63, 18.44, 18.23 and 17.92 milligauss (mG) respectively (high, medium, low and ambient temperature set). ELF-EMF of high temperature set was higher than data of medium, low and ambient set in all the distances.ELF-EMF from convective air warming system is higher in condition of more close location and higher temperature. ELF-EMF within thirty centimeters exceeds 2mG recommended by Swedish TCO guideline. https://ijph.tums.ac.ir/index.php/ijph/article/view/3762 https://ijph.tums.ac.ir/index.php/ijph/article/download/3762/3425