The only concern really is the radiation. Most of the bombs tested in Nevada were thermonuclear (fusion, hydrogen bombs), there a few pure fission bombs tested in 1951 – 1955 but that was very early on with tiny yields. Already in 1953, they were mostly testing thermonuclear bombs, they’re just not as radioactive.
You use a tiny fission bomb to set off a much bigger hydrogen bomb. You try naturally to make the fission part as small as possible because the fusing of hydrogen is what’s gonna get you to boom.