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Especially sunscreen on overcast days. UVA doesn't cause tanning or sunburn, but it does pass through clouds and damages the skin.
by dade_ 5y ago
Especially sunscreen on overcast days. UVA doesn't cause tanning or sunburn, but it does pass through clouds and damages the skin.
- gpt5 5y ago+1. Some of the worse burns I had were during overcast days.
- colechristensen 5y agoI hear this a lot but do not remember a single sunburn on an overcast day despite having very light skin. Is this a southern latitude thing?
- lifeisstillgood 5y agoAs I understand it (and this seems too pat) UV-B "burns" and UV-A does the cancerous damage. I believe it's to do with depth of penetration. So you can get skin damage without burn.
- noodlenotes 5y agoLatitude makes a huge difference. The UV index is 13 in Mexico City today vs 5 in London. Depending on your skin type, you would burn in 10 minutes in Mexico City vs 30-45 minutes in London. This is because sunlight hits the Earth at more of an angle the farther north and south you get, so it passes through the atmosphere for a longer time and more UV gets absorbed before hitting you. This is the same reason you don't burn as much in the early morning and late afternoon.
- megablast 5y agoI’ve never had a sunburn from a cloudy day in Australia.
- godelski 5y agoMexico City is near the equator (1,342.38 mi). London (3,558.31 mi) and Australia (Sydney: 2,339.14 mi) aren't? Though Darwin is closer (860.93 mi) to the equator than Mexico City. So I guess you could be right but if you're like most people and live in NSW or Perth, you probably live a lot further away.
- D1CA1890 5y agoThe altitude of Mexico City would also have an effect, compared to a location like Singapore at sea-level. Time-of-day would have far more bearing than latitude, since most human population is within ±45.
- SapporoChris 5y agoI was of the mindset that elevation was more of a factor in UV index than latitude, but I just learned differently. Thank you. I found a nice discussion of the calculation: https://www.epa.gov/sunsafety/calculating-uv-index-0 https://www.epa.gov/sunsafety/calculating-uv-index-0 It hand waves a bit on how latitude is factored in but states clearly that every km of elevation increases exposure by about 6%. Mexico City: 2,240 m London: 25 m So 12% more UV for Mexico City based on elevation. The elevation is important but not the primary factor. Anecdotally, I have been in Mexico City. I did most of my walking in the mornings and still would sunburn on an sixty minute walk. I did not use any protection.
- zzt123 5y agoClouds do tend to diminish UV, but not significantly so as to make you UV-invulnerable. In the UV tracking app I use, the largest cloud-effects I’ve seen are in the range of 1-3 points decrease. So, UV index of 5-7 instead of 8. Depending on the baseline UV level during exposure, that difference could be significant (5 index down to 2) or not that significant (14 down to 11), in terms of expected minutes until sunburn.
- curmudgeon22 5y agoagreed. I live in Canada and can't recall ever getting a burn on an overcast day.
- zzt123 5y agoThe max UV index in Toronto tomorrow is a 6. On a sufficiently overcast day, that may become a 3, maybe even lower. That would have a very significant effect on odds of sunburn. Equally overcast on a high UV day in Bangkok on the other hand...
- ijidak 5y agoI'm black, and thought I couldn't burn. Then I visited Panama.
- sunstone 5y agoYou learn something new everyday, whether you want to or not. :P
- KozmoNau7 5y agoI got sunburned on an overcast day in Ireland, of all places. Walking around a whole day outside without anything covering my head turned out to be a bad idea.
- sunstone 5y agoI've had a few living at 49degrees north and it happens in spring with temperatures around 20. You feel comfortable, light cloud cover makes the sun unnoticeable and you're playing tennis for four hours around noon. Right around dinner time you notice that you've got a pretty solid burn that just crept up on you.
- andreilys 5y agoHow do you balance wearing sunscreen with getting the necessary vitamin d exposure from the sun?
- iknowstuff 5y agoEveryone is vitamin deficient in one way or another. We all should supplement anyway, so just supplement vitamin D.
- GeneralAntilles 5y agoSupplementing vitamin D is unlikely to hurt in most cases (if you're taking a useful form like D3 and if you're not acutely deficient in vitamin A and K2), but it both isn't that effective on its own—oral supplementation tends to take a long time to fix deficiency and may work particularly poorly for people with absorption issues—and doesn't provide the full benefits of sun exposure (nitric oxide being a big one, but there are other immune, blood pressure, and inflammation benefits, as well as stuff related to how vitamin D is produced through sun exposure to the skin). For me, better mental, cardiovascular, immune, and bone health is more important than apparent skin aging and a marginally increased risk of skin cancer, but everybody has to make their own trade-off decisions. A moderate amount of sun exposure is beneficial to most people. Avoid burning—especially severe burns with kids, which seem to be a big factor in eventual skin cancer risk—by controlling length of exposure and by wearing clothes to cover your skin if you can't control length of exposure.
- randycupertino 5y agoI put sunscreen on my face and neck let my arms and legs soak up vitamin D.
- playing_colours 5y agoOur skin needs a moderate exposure to the sun, like 3-4 times a week for 15 minutes in summertime.
- gamzer 5y ago
- zzt123 5y agoSpeaking of UV-A, I’m not a conspiracy theorist on this, but it reminded me that a common retort I’ve read given to “RF, routers, etc cause cancer” theories is that those are non-ionizing radiation and therefore are safe. Yet, UV-A is non-ionizing and definitely does cause cancer. Just a random brain connection that was made.
- sudosysgen 5y agoUV-A mainly causes cancer by denaturing proteins such as collagen and vitamin A, which indirectly can cause cancer. That's still heavily dependent on the energy of the photon, so real low frequency radiation like that used in telecoms can't use similar mechanisms.
- Pulcinella 5y agoUV-A is generally non-ionizing, but that doesn’t mean it can’t cause electronic transitions that lead to chemical reactions. https://en.wikipedia.org/wiki/Molecular_electronic_transition https://en.wikipedia.org/wiki/Molecular_electronic_transitio... UV-A can create Thymine diners in your DNA, for example. No ionization required. https://en.m.wikipedia.org/wiki/Pyrimidine_dimer https://en.m.wikipedia.org/wiki/Pyrimidine_dimer
- spoonjim 5y agoWhy do people feel the need to deny being “conspiracy theorists?” Many conspiracy theories have been proven true: they were spying on all of your phone calls, they did know that cigarettes cause cancer, etc. Would it be so surprising to find out that consumer RF was giving us cancer but the tech industry was making too much money off it to tell us?
- beagle3 5y agoBecause one of those successful conspiracies was to brand the natural word “conspiracy” to imply craziness.
- playing_colours 5y agoTo me “a conspiracy theorist” is a person with a specific mindset: they dedicate their time to learning about and sharing conspiracy theories - usually they believe in several ones - with an unconscious intention not to find real answers, but to prove their beliefs. Cautiously suggesting that some unproved assumption may be true and needs more research or using scientific methods to validate it does not make a person “conspiracy theorist” or “freak”, though ,unfortunately, they are often labelled as such in our society.