How long does SPF 50 last?

[AJBlitz]

So I am currently using Beauty of Joseon Relief Sun Rice + Probiotics, and I apply it every morning at 7 a.m. My school ends at 3–4 p.m. I am mostly inside, with only a short 15-minute break outside. In my city, the UV index reaches 8 on sunny summer days. So will the protection be enough after 3–4 p.m. when I go home? And will it have some impact on acne and post inflammatory erythema. Thanks.

 

[BucketCrab]

Chemical sunscreen doesn't wear off, but it can cause acne. It lasts a few hours typically.
Mineral sunscreen generally doesn't cause acne and lasts indefinitely, but it can be rubbed off or it can dribble off if you sweat.

You should be ok if you're mostly inside though, unless you're right next to the window and the sun shines on you.

 

[AJBlitz]

I mean I don't care about the uv when I am inside but right now I am on adapalene/differin and after school I go out and uv index is like 5-7, I chosed quality sunscreen beauty of joseon SPF 50 probiotics.