Curious how we never get articles about the harm caused by western countries nuclear tests...

Well, they haven't conducted any since 1996.

> Since the treaty's opening for signature in 1996, only sixteen nuclear tests have been conducted, all by non-signatory states: Pokhran-II by India and Chagai-I by Pakistan in May 1998, and six tests by North Korea from 2006 to 2017.

Why were nuclear explosions harmless before 1996?

They weren't. Hence the treaty.

because they're not doing them anymore