It’s natural to want to understand the safety credentials of hydrogen compared to diesel. We’re used to the dangers of diesel, but less familiar with hydrogen.
There are differences: hydrogen is not poisonous, and it’s carbon free. Hydrogen is light, meaning if leaked it disperses rapidly and upwards. Diluted hydrogen is less likely to catch fire than diesel. If ignited hydrogen does not burn as hot as diesel. Hydrogen does need storing safely under high pressure or in a cold liquid form. When stored and managed properly it's no more dangerous than diesel.