As per chx's answer, please do not wear the SN98 pleated surgical mask on Vienna public transport. The local laws do not allow you to wear such a mask in such a situation.
An FFP2 / KF94 / KN95 / N95 mask is a far better choice than an SN98 mask or another pleated surgical mask. It may offer significantly better protection to both you and to those around you.
I will try to help you understand the difference between media filtration rate and fitted filtration rate.
The SN98 mask has a media filtration rate of 98%. However, because of its pleated design, it leaks unfiltered air through the sides. Therefore, it may provide a fitted filtration rate of 20% or even worse.
An FFP2 mask has a media filtration rate of 95%–99% or better. Because of its careful 3D design and shape, it may seal to the face of the wearer. (Not guaranteed.) Therefore, a well-fitting FFP2 mask may provide a fitted filtration rate of 95%–99% or better, which is far better than that of the SN98 mask.
The SN98 surgical mask is better than a cloth mask; but a well-fitting FFP2 / KN95 / N95 mask is superior to the SN98. I would encourage you to buy some FFP2 / KN95 / N95 masks, and to wear them on public transit and in all indoor public places.
In Europe, the 3M VFlex 9152 FFP2 and the 3M Aura 9320+ FFP2 are reasonably popular choices.
In the US, you can wear any random KN95 mask with ear loops; or you can buy the 3M VFlex 9105 N95 with headbands.