Radiosonde balloons can be inflated either with hydrogen or with helium. Hydrogen has a slightly greater lifting power than helium, it is much cheaper than helium, and it is usually available in most parts of the world. Hydrogen is delivered compressed in steel cylinders, or it can be generated locally by stationary or portable generators. Hydrogen is a highly explosive gas when mixed with air.
| WARNING To minimize the risk of fire or explosion, take precautions strictly into account in organizing the balloon-filling shed and working procedures. |
| WARNING Normally the balloon-lifting gas (hydrogen or helium) is supplied in gas bottles, but hydrogen can also be produced with a hydrogen generator. Carefully study the operation and safety instructions for the gas bottle facilities or the hydrogen generator. |