The FAA would argue that improved airport security has made flying safer during the past year. However, more sensitive metal detectors and random security checks don\u2019t address the medical risks of flying?from stress symptoms and dehydration to more serious maladies like blood clots and radiation exposure.When passengers are packed into coach-class seats like sardines, the lack of mobility can lead to blood clots. Dr. Peter Degnan, an integrative medicine physician at Equinox Health and Healing in Portsmouth, N.H., advises flyers to select an aisle seat for additional freedom of movement. Since Sept. 11, the stress and fears associated with air travel have increased significantly. Degnan recommends relaxation techniques like deep breathing to soothe nerves. One additional health risk is exposure to radiation, which is inevitable at the high altitudes that planes travel. The risk is more significant for airline personnel, who were actually reclassified by the FAA as radiation workers in 1996. For the average flyer, radiation exposure is both minimal and unpreventable.