Complex sentence: In the city, the Doctor learns from a Geiger counter that the planet is radioactive, and, in view of the fact that they are feeling unwell, deduces that they are developing radiation sickness.
Split into simpler sentences: In the city, the Doctor learns from a Geiger counter that the planet is radioactive. In view of the fact that they are feeling unwell, he also deduces that they are developing radiation sickness.