Glasgow Nights (Doctor Who RPG)
The Vortex emits a special type of temporal background radiation known as Artron Energy. Those who travel through it absorb some of this energy into their bodies, and those who make frequent use of time travel devices will often have high Artron Levels that can be readily detected by time sensitive equipment. Certain spacetime fissures are also known to emit Artron Energy.
Fortunately, this radiation is benign for the most part and is no more likely to adversely affect the health of those exposed than any other type of low-intensity radiation. In fact, the energy is highly unusual in that it has qualities similar to the psychic life energy possessed by living beings and can strengthen mental abilities.
There is one exception to the “benign” nature of Artron Energy. If the two versions of the same individual (whether from different universes or from different points of the being’s own timeline) touch, the effect is much more explosive. Such an explosion usually renders both versions of the individual unconscious, injures those nearby, and shorts out technological equipment nearby.
(adapted from Doctor Who: The Time Travellers Companion)