DNA 1240H-2 19 August 1973 In Some cases, the asymptomatic interval is even shorter than noted by Rider and Hasselback. Fig. 18-19 was prepared by Dr. Thomas Mobley of Air Force Weapons Laboratory, and will be published in a forthcoming Technical Report. The figure illustrates radiation effects on a young man (about 6 ft 4 in. tall, weighing about 180 1b), observed and documented by Dr. Mobley at the Ontario Tumor Clinic. The asymptomatic interval after irradiation in this case was only about 25 min, and for 5 hr after that, the patient was incapable of performing any task. Similar effects were noted, according to Dr. Mobley, in the treatment of patients at Naval Hospital, San Diego, California. 18.7.2 Thermal Radiation Thermal radiation from underwater bursts is either negligible or non-existent, and will cause no injuries or incapacitation to shipboard personnel. Thermal radiation from a surface burst will not affect below- decks personnel, but the eyesight and/or exposed or Lightly covered skin areas of topside personnel may be affected. Although no CDC casualty or risk criteria are given for either retinal burn or flashblindness, it should be noted that vision is vital to task performance of many topside personnel. Visual acuity is only slightly affected by a retinal burn (a permanent effect), unless an individual is looking directly at the fireball, a circumstance considered unlikely. How- ever, vision may be immediately temporarily, partially, or totally impaired due to the bright flash of a nuclear burst, even though the burst is not directly in the visual field. Time for recovery from this condition, termed flashblindness, may be from several seconds to several hours, depending on exposure conditions. Such effects can occur at far greater distances from surface zero than are hazardous due to any other weapon effect, and the possibility that some topside personnel may be unable to perform their duties should be noted. 18-28