How to Select a Gas Mask for Chemical Warfare Protection?

When facing a chemical warfare situation, choosing a gas mask is crucial to protect against the following chemical elements¹:

1. **Nerve Agents**: Such as Sarin or VX.
2. **Blister Agents**: These agents include sulfur mustard gas and Lewisite, causing burns and blisters.
3. **Cyanide Compounds**: Such as hydrogen cyanide or cyanogen chloride, which interfere with oxygen uptake by red blood cells.
4. **Arsenicals**: Such as Lewisite, which have a very strong and unpleasant odor but are not as toxic as riot agents or vomiting agents.
5. **Toxins**: Such as Botulinum toxin.
6. **Incapacitating Agents**: These substances cause limited harm, usually not resulting in permanent injury or loss of life. Incapacitating agents, along with riot agents, are referred to as non-lethal agent types.

Any suggestions on how to select a Gas Mask?
Thanks in advance