Sunbathing and Vitamin D

[empleat]

Hello,

I have couple questions about sunbathing for gaining Vitamin D. I Am 26.

Firstly I would like to ask, what is maximum safe dose of Vitamin D2? Mycologist found out that leaving mushrooms on the sun increases greatly their vitamin D contents. At the bottom there is a study where people took 24 000 IU of Vitamin D2 daily 4 days per week for 5 weeks: https://fungi.com/blogs/articles/place-mushrooms-in-sunlight-to-get-your-vitamin-d Ctr+f to: A natural question to ask is how much of the vitamin D

But isn't 24 000 IU too much? I read everywhere that Vitamin D (from food) UL is 4000 IU!!!

...Next this concerns sunbathing:
1. I googled that sun has to be at least 50 degrees above horizon in order to get enough Vitamin D. Is this correct? I used this map to find exact position of the sun at time https://www.sunearthtools.com/dp/tools/pos_sun.php?lang=en
It says that after 3PM sun will be at 50.2 and lowering... So actually best time for me would be between 2-3PM, as after 3PM sun starts to get too low! I live in Czech Republic.

2. Is it correct that between like 11-3PM body is also more efficient at creating Vitamin D, also it may depend on a person I guess.

3. I found that only 25% of body surface should be exposed to the sun. Is this taken for whole body area, or only for one side? Because then it would be (50%). I didn't find answer to it in multiple articles. E.g. on healthline they speak of wearing tank and shorts (you can be also walking) as you don't have to sunbathe only lying on the ground. So I assume it is meant as 25% from total area of the body surface, is that correct?

4. It is said: that you need like 10-30 minutes 3 times per week. How do I establish exact time I need? It shouldn't matter if it is a little bit longer, right? As you can't overdose with Vitamin D, but only burn your skin! So if I avoid that, I should be fine right? I have cold skin tone as far as I know (as I have purple and blue veins and very bright skin and I wasn't out years almost)! I will test that out what feels comfortable and if that will be too much I will add some more...

5. Years back I had diagnosed Vitamin D deficiency, don't remember exact mol. But I wasn't last 6 years almost out, so I have pretty much guaranteed low Vitamin D levels. Is it okay start sunbathing regularly, or should I start more slowly. I will consult also my GP about this!

6. Do I need account for ozone, or air quality also? Not sure, if you can determine ozone quality per area anyways, but there hydrometeorologic maps...

Anything else to watch for?

Thanks!

[empleat]

There doesn't seem to be edit: to add: my GP said there is no limit on Vitamin D2 and it should be fine!