actually i'm looking at recovery sandals..not shoes sry
BTW i cant find back the post which you asked in other haze thread about exercise, i think what you can do is to wear a KF94 and just do zone 2......long 3hr zone 2 also no big issue, that is what i am doing.
No real risk one, it's not that super dissimilar to high altitude training. But dont get me wrong, wearing a KF94 is totally not the same as high altitude training (actually it doesnt work in terms of training).
Only "issue" is that it gets uncomfortable due to the humidity under the mask esp coz of sweating. If you want, can bring a change of mask(s) and do it a few times during the session.
ps. of coz pls do not do this for your LT2 or worse vo2/anaerobic workouts if you are also into those.......you are probably gonna faint or something. lol
For this, you'd still need to aim for a clear window