Here are a few problems which probably won't affect you unless you work at NASA: hydrogen burns with a very pale blue flame that is almost invisible in daylight, hydrogen is highly flammable, and hydrogen tends to leak through the tiniest of cracks.
"That makes it a hazard, as the element is highly flammable, to the point where high-pressure joint leaks can cause combustion," NASA explained in a 2015 post. "As a result, detecting leaks is a top priority, but it’s also a challenge, because the gas—and the flame it emits—are odorless and colorless."
In 2003, NASA and the Florida Solar Energy Center came up with a solution in the form of a tape that changes color when exposed to the element. Before that, ultraviolet sensors were used to detect flames. The solution used before that, however, was far less dignified – and a whole lot more fun.
"Given those stakes, imagine the task of having to monitor liquid hydrogen as it flows through a few miles of pipeline—which is what NASA had to do in preparation for every Shuttle launch, when hundreds of thousands of gallons were transferred from a holding tank to the launch pad for fueling," NASA explained. "In the Apollo days, detecting a flame from one of those leaks was accomplished by using the 'broom' method, whereby workers would take a broom and walk around with the head stretched out in front of them. If the head began to burn, there was a leak."
The solution was practical and clearly worked, even if it probably wasn't the most reassuring sight to see the "is my broom on fire" test conducted at an organization that hurls people into space. The broom method was also used by firefighters responding to hydrogen fires. Thankfully it has been superseded by better methods, which aren't as susceptible to it being a bit windy outdoors.