[tptacek]

I think the chart would do better if removed from the arbitrary constraint of XKCD's page framing; if, for instance, a suitably large canvas was used, so that the eyes could immediately grasp the comparatively minimal exposures from common radiation sources to (say) the gigantic exposures from Chernobyl.

It's clearly within Munroe's capability to make such a graphic; he did this one on a deadline. I'm not criticizing Munroe (though: not an XKCD fan), just making an objective assessment of the graphic.

And, like I said: here's a case where a graphic, even an imperfect one, probably communicates rich information more effectively than prose. Unlike the "relative sizes of data" infographic upthread.