1500 remains were found at Pompeii. As for Chernobyl, the death toll is estimated to be about 4000. Not many direct deaths but a lot of cancer caused by radioactive fallout.
I visited Chernobyl a few years ago, our group used special radiation detectors from https://ecotestgroup.com/products/new-sprd-spectra/ to measure the level of radiation and in some places the radiation level was still above the norm. I think that radiation is one of the most dangerous thing 'coz even in tiny doses radiation could cause serious diseases.