The biggest problem with that chart is that it mixes different time scales, which it only indicates in the text, not in the visual comparisons.
Take one of the ones that measures an hour's exposure and multiply it by 24. Or a day and multiply it by 365. Suddenly the visual comparisons look much, much different.
As mentioned in the BBC article though, doing that kind of math does not lead to an accurate result, due to the fact that your body is constantly healing. It's the bursts of radiation that are most damaging.
Yeah, this was one of my big complaints with that. However, it's not prevalent enough to disregard it. It's by no means scientific, but I think it gives a good high level orders-of-magnitude view, largely.
