Fun fact: 0.3 micron particles are the most penetrating particles of any size, including smaller particles. It’s counterintuitive, but 0.1 micron particles will be filtered out more easily than 0.3 micron particles. [0] That’s in fact why all masks are rated this way, since it gives you the absolute worst case. It’s fair to say that an N95 would filter out at least 95% of all particles.
Wearing a mask has additional benefits of filtering out pollution, microplastics in the air and blocking common flu, pollen etc.