However, scientists point to the the dangers of sudden changes in space weather — the radiation present in space, such as solar wind of heavy ions and atomic nuclei. These changes include ground level enhancement , when the charged particles from the Sun have enough energy measurable at the Earth's surface. They also include solar particle events when particles emitted by Sun — mostly protons — are accelerated by the Sun's atmosphere or space by a coronal mass ejection shock.
“Exposure to elevated levels of ionising radiation, such as those possible during GLE or SPE events, has been noted by the UK Health Protection Agency, to potentially ‘cause damage to DNA, lead to mutations, uncontrolled cell division and lead to malignancy’,” the The study reckons that existing regulation applies to space flight crews rather than paying passengers. “For the potential space tourist, regulation is still catching up with this new industry. Further input into potential future regulation will be required going forward, noting that current fit-for-purpose legislation for radiation protection and associated risk assessment for space tourism does not exist,” the paper says.