A few years with a half-life of less than four days? I doubt you could perceive any glow after more than a few weeks.

In a year the radon would've undergone about a hundred halvings, so around one 10^30th of the original radon nuclei would be left. Which is to say, almost certainly zero. One mole worth of radon would've decayed down to the last atom after less than 300 days (mostly to lead-210, which would then comparatively slowly decay to stable lead-206 with a half-life of about 22 years).