Does Taking Breaks from Sunlight Prevent Sunburn (If the Total Exposure Time is the Same)?

[kyphysics]

rall)?

What I mean is, suppose I were to spend 1 hour total in the sun. If I spent it in "3 chunks" of 20 minutes with 10 minutes between each chunk (in the shade), would that reduce my sunburn damage chances vs. spending the full 1 hour entirely in the sun?

I was mowing grass in 90 degree heat the other day and did the 3-chunk method. Only had facial sunscreen (no body bottles in the house) and applied the remainder of the facial SPF 30 screen to my face and parts of body...but ran out and had parts of skin exposed.

I feel "burnt" afterwards. Skin is in pain. But, during that mowing session, I thought I was taking precautions by taking those 10 minute breaks in the shade. I wonder if that method is at least better than 1 hour straight?

 

[Rive]

As far as I know with such short terms, it is a 'no'. If you let your skin adapt (tanning) between exposed periods (long enough periods) then that will help (but applying sunscreen is still far better).

 

[Astronuc]

What I mean is, suppose I were to spend 1 hour total in the sun. If I spent it in "3 chunks" of 20 minutes with 10 minutes between each chunk (in the shade), would that reduce my sunburn damage chances vs. spending the full 1 hour entirely in the sun?

I was mowing grass in 90 degree heat the other day and did the 3-chunk method. Only had facial sunscreen (no body bottles in the house) and applied the remainder of the facial SPF 30 screen to my face and parts of body...but ran out and had parts of skin exposed.

I feel "burnt" afterwards. Skin is in pain. But, during that mowing session, I thought I was taking precautions by taking those 10 minute breaks in the shade. I wonder if that method is at least better than 1 hour straight?

Best to mow early in the morning (2 to 3 hours after sunrise) or late afternoon (2-3 hours before sunset). Getting sun exposure between 11 am - 3 pm local time can expose one to a lot of radiation. If one has not been in the sun very much, then one should get little doses of sun (e.g., 15 minutes) with long wait times in between. I'd suggest 15 minutes of mowing followed by one or two hours inside, if one decides to be outside in the middle of the day. Or wear, protective clothing - long sleeves and broad brim hat.

If one received significant sunburn from one hour of sun exposure, then one's skin is very sensitive, and one should limit exposure.

I used to spend 8 to 10 hours in the sun during the summer, working in shorts. I got a very dark tan. I wouldn't do that now, since I'd increase the risk of skin cancer, and my father has already had some basal carcinomas removed from his head and neck.

 

[kyphysics]

If one received significant sunburn from one hour of sun exposure, then one's skin is very sensitive, and one should limit exposure.

I used to spend 8 to 10 hours in the sun during the summer, working in shorts. I got a very dark tan. I wouldn't do that now, since I'd increase the risk of skin cancer, and my father has already had some basal carcinomas removed from his head and neck.

I do tan very easily.

If I took a walk in the sun for 15 minutes, then I'd be tanned. I don't know if that's normal, but that's me - my genetics. If I spent 8 to 10 hours out, I don't know what I'd look like! I don't want to know!

As for a burn, I think I got a slight sunburn. The skin color is not particularly red (maybe slightly pink in a few areas), but the "feel" of my skin is nonetheless very tender with some slight pain in some places.

When my skin gets super heated in the sun, it can feel painful. That's why I took breaks and went into the shade. My thinking was that that cooled me down and reduced "damage." Never going to cut grass in 90 degree heat again. This particular day I sort of "had to" given my schedule and rain coming...next time I'd rather let the grass just get super long vs. getting burned. Not worth it.

 

[Astronuc]

As for a burn, I think I got a slight sunburn. The skin color is not particularly red (maybe slightly pink in a few areas), but the "feel" of my skin is nonetheless very tender with some slight pain in some places.

Pink or reddining is solar erythema. Usually, that should take a few hours of exposure. If one gets pink or light reddening, that would indicate sensitive skin. One should use something like Zn oxide on exposed skin. I would use that when I was riding a bike for hours in the sun, and wearing shorts and T-shirt.

I grew up close to beaches during my first 5 years, so I spent a lot of time in the sun. Now I have to protect my skin.

 

[kyphysics]

Now I have to protect my skin.

Yeah, I need to reload on sunscreen. https://www.bloomberg.com/news/vide...ound-in-popular-sunscreens-video?srnd=premium

There's been recent news of a possible carcinogen found in many popular sunscreen brands.

 

[Astronuc]

There's been recent news of a possible carcinogen found in many popular sunscreen brands.

Yes. Apparently some benzene found its way into some Johnson & Johnson sunscreen brands. JNJ issued a recall.

https://www.jnj.com/johnson-johnson...creen-products-due-to-the-presence-of-benzene

 

[Tom.G]

This site lists multiple sunscreen brands with trace amounts of benzene, most of them seem to be below the level of concern:
https://www.verywellhealth.com/benzene-popular-sunscreens-5188418

It also has a link to tips for avoiding skin cancer:
https://www.verywellhealth.com/sun-safety-101-3010829

Cheers,
Tom

 

[Paul001]

rall)?

What I mean is, suppose I were to spend 1 hour total in the sun. If I spent it in "3 chunks" of 20 minutes with 10 minutes between each chunk (in the shade), would that reduce my sunburn damage chances vs. spending the full 1 hour entirely in the sun?

I was mowing grass in 90 degree heat the other day and did the 3-chunk method. Only had facial sunscreen (no body bottles in the house) and applied the remainder of the facial SPF 30 screen to my face and parts of body...but ran out and had parts of skin exposed.

I feel "burnt" afterwards. Skin is in pain. But, during that mowing session, I thought I was taking precautions by taking those 10 minute breaks in the shade. I wonder if that method is at least better than 1 hour straight?

Radiation exposure is accumulative.

 

[jack action]

What I mean is, suppose I were to spend 1 hour total in the sun. If I spent it in "3 chunks" of 20 minutes with 10 minutes between each chunk (in the shade), would that reduce my sunburn damage chances vs. spending the full 1 hour entirely in the sun?

It is the same as saying:

«If I cook a chicken for "3 chunks" of 20 minutes with 10 minutes between each chunk, will it be less cooked than if I put it 1 full hour in the oven?»

The answer is no. What will influence is the UV index, which would be the equivalent of the temperature setting in my oven example.

 

[DaveC426913]

It is the same as saying:

«If I cook a chicken for "3 chunks" of 20 minutes with 10 minutes between each chunk, will it be less cooked than if I put it 1 full hour in the oven?»

The answer is no. What will influence is the UV index, which would be the equivalent of the temperature setting in my oven example.

Waitaminnit. Both cases are - at least in principle, though not necessarily in practice - true.

Cooking a chicken in 3 chunks of 20 mins will be less cooked than one chunk of 60 minutes - because the chicken will cool during the breaks. It needs to get to a certain temp to cook properly, and if it keeps cooling, it will spend less time (if any) at the proper temp.

Likewise with sun exposure. In principle, taking breaks would allow the skin to tan and form some protection - though, in practice, the breaks would need to be much longer.

 

[BWV]

So is it equivalent to get an hour of sun per day for 90 days or 90 straight hours of sunlight?

clothing > sunscreen. Worked for a painter one summer in college and it struck me how much my Mexican coworkers respected the sun - loose, light colored long sleeve shirts and long pants with a broad rimmed hat. Tried this and was surprised how much more bearable it made 106F TX weather.

 

[kyphysics]

Radiation exposure is accumulative.

Is there a "self-healing" effect from the body to radiation from the sun that would impact things?

 

[jack action]

Waitaminnit. Both cases are - at least in principle, though not necessarily in practice - true.

Cooking a chicken in 3 chunks of 20 mins will be less cooked than one chunk of 60 minutes - because the chicken will cool during the breaks. It needs to get to a certain temp to cook properly, and if it keeps cooling, it will spend less time (if any) at the proper temp.
View attachment 287641

Likewise with sun exposure. In principle, taking breaks would allow the skin to tan and form some protection - though, in practice, the breaks would need to be much longer.

We're talking radiation here and it seems to reach "cooking" temperature pretty fast:

Sunburn can occur in less than 15 minutes, and in seconds when exposed to non-shielded welding arcs or other sources of intense ultraviolet light. Nevertheless, the inflicted harm is often not immediately obvious.

After the exposure, skin may turn red in as little as 30 minutes but most often takes 2 to 6 hours. Pain is usually strongest 6 to 48 hours after exposure. The burn continues to develop for 1 to 3 days, occasionally followed by peeling skin in 3 to 8 days. Some peeling and itching may continue for several weeks.

So the visible effects would appear long after the damage is done.

 

[russ_watters]

So is it equivalent to get an hour of sun per day for 90 days or 90 straight hours of sunlight?

Yes, there is a time constant for damage/repair, but it's longer than one day (and you can't get 90 hours of sun exposure in one day).

What taking breaks can do for you, though, is allow time to notice the damage/initial repair effort(it doesn't happen instantly, but continues after you leave the sun) and respond by ending your exposure.

 

[jim mcnamara]

The Relationship between Ultraviolet Radiation Exposure and Vitamin D Status:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257661/
Explains the basics of vitamin D3 synthesis and UV damage control.

 

[StoneTemplePython]

I think a lot of people on this thread are so used to linear approximations (e.g. averages) that they neglect (negative) convexity behavior.

Sun burns aren't just about cooking cells but setting off an oxidation chain that temporarily overwhelms your body's ability to repair.

People interested in exercise and fitness often see a mirrored version of this question. Basically if I am 'working out' at sufficiently high intensity (whatever that means) for 60 minutes a day, is the 'health benefit' equivalent if I do 1 x 60 minutes vs 3 x 20 minute vs 6 x 10 minutes, etc. The general belief is tweaking the duration vs rest period changes the convexity response with respect to various health benefits of exercise but we don't really understand much beyond this.

 

[BWV]

Thinking about trying an experiment where I take one shot of tequila per day for a month then on the first of the next month do 30 shots in an hour

 

[BillTre]

If you are willing to ignore general effects of illumination and only consider sunburn, you could set up quite a set of experiments, on patches of your skin, that are either covered or not covered (with removable and replaceable, sunlight blocking tapes) when exposed to the sun.
Lots of neighboring spaces to simultaneously test lots of different exposure schedules.
You would need controls for the tape application (maybe the unexposed side of the body).

There also longer term effects of sun exposure (like tanning, modification of skin pigmentation, which change on the scale of days), that would modify the effects more time delayed exposures would have.

 

[DaveC426913]

We're talking radiation here and it seems to reach "cooking" temperature pretty fast:

So the visible effects would appear long after the damage is done.

While that may be true, radiation damage also doesn't stop - it's cumulative. So, taking a break will still give the skin time to start protecting itself (though, again: it would take a lot more than 10 minute breaks in the shade for it to have any mitigating effect on damage.)

So I stand by what I said:

• - a chicken cooked in discrete chunks will (most likely) be less cooked than one cooked in one swell foop.
• - taking breaks from the sun will - in principle, at least - give time for the body to build a little defense, though the time frame is much longer than minutes.

That being said: the OP's question is answered - in a practical way - with "No. Sunning, punctuated by ten minute breaks, will not cause less damage than full continuous sun of the same total duration