So I stumbled upon this thread and read it multiple times over the last couple days as I was trying to learn more about the Respro, the EN149FFP1 standard, and compare it to my North B5500 and its slew of cartridges. If you want to learn more about the standard, search for "EN149 FFP1" instead of "EN149FFP1"

There is a whole slew of masks conforming to this standard. The masks are for fine particulates and water soluble solvents. I am not sure if this means they are good for organic solvents. (can anyone answer this please?)

Regardless, I believe the North B5500 is easier to breath through then the Respro, can be seal tested, has a good selection of cartridges to choose from, and sits better on the nose ridge (i.e. more comfortable) than the Respro. However, it does look much more post-apocalyptic than the Respro. Also, if you want to wear a helmet and put the mask or take it off, the Respro will suit you better.