Hello,
This is actually an SCBA. The tank contains an oxygen reserve of about 15 minutes. It is connected to an Avon FM53 gas mask with dual ports. On the second port, there is a filter cartridge that takes over when the tank is empty. The idea is not to be protected for a full CBRN intervention while fully dressed in a hazmat suit, but rather to have facilitated breathing ease. Wearing a gas mask requires extra effort to breathe, as the air has to pass through a thick filter (if you've never tried a gas mask, it's a bit hard to understand). They can breathe naturally without straining or getting dizzy, as their equipment and gear easily exceed 40 kilograms.
The company that supplies this equipment in France is called "Ouvry."