Why is helium safer than hydrogen for filling balloons and airships?

Helium is considered safer than hydrogen for use in balloons and airships primarily because it is an inert gas that does not burn.12

While hydrogen is the lightest known gas and provides superior lifting capacity, it is highly flammable. This flammability has historically led to numerous fatal disasters, most notably the 1937 destruction of the Hindenburg, which caught fire while landing in New Jersey. Although the Hindenburg was originally designed to use helium, it was filled with hydrogen due to export restrictions at the time.23

In contrast, helium is a noble gas that does not react or combust, making it a much safer, albeit less buoyant, alternative for lifting applications.12