Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time. On April 16, 2017 there were 11 potentially hazardous asteroids.
Radiation therapy is often delivered from a machine outside the body. One of the most common side effects is a skin condition called radiation dermatitis, which can range from a mild, red rash (erythema) and itchy, peeling or flaking skin (dry desquamation) to a more severe reaction with blisters and wet, peeling skin (moist desquamation).
The biological effects of UV radiation do not appear readily, so individuals who are often overexposed become aware of the damaging effects and the extent of damage over time. If exposure is sufficiently high, systematic effects such as nausea, fever and malaise may transpire. In cases of tremendous exposure, premalignant or malignant changes may ensue (2). Moreover, skin cancer, cataracts and immunosupression are the primary health effects associated with UV-B radiation exposure (3).