I've seen that we search for exoplanets with life by using spectral analysis to estimate the temperature, atmospheric composition, etc. of these planets, and se

I've seen that we search for exoplanets with life by using spectral analysis to estimate the temperature, atmospheric composition, etc. of these planets, and seeing whether or not they fall within a range that is similar to Earth's. I wonder if it would also be instructive to search for planets who exhibit signs of a man-made apocalypse, like massive nuclear fallout.