Thank you Ded, Bigmarco, and Jake !
Here in the UK I use moisturising sunscreen with SPF 15 and UVA protection. In the tropics or southern Europe, SPF 50 with high UVA protection. I’m lucky in that my skin tans easily and I don’t burn in sunlight, but as I like outdoors activities I do try always to use sunscreen.
Here’s why :-
• Solar or artificial ultraviolet irradiation can harm the skin. It’s responsible for various skin disorders, and some drugs may cause increased skin sensitivity to UV light. These conditions (as well as sunburn) may occur after relatively short periods of exposure.
• The effects of exposure over longer periods include ageing changes and more importantly risk of skin cancer, especially in fair / white skin.
• Melanoma is the most serious, but thankfully the least common skin cancer, and it does not directly result from sun exposure, but depends more on accumulated exposure over years.
• By far the most common skin cancer is " rodent ulcer " ( basal cell carcinoma ) which does however usually remain localised to the sun-exposed site of origin. Squamous cancer is the next commonest, also directly the result of sun exposure, and may spread elsewhere. These tend to affect older people.
• Solar UV radiation is around 200–400 nm in wavelength. Medium wavelengths (290–320 nm, or UVB) cause sunburn. Long wavelengths (320–400 nm, or UVA) are responsible for many photosensitivity reactions and other skin diseases. Both UVA and UVB cause long-term damage and changes responsible for skin cancer and ageing.
• Sunscreen preparations contain substances that protect the skin against UVA and UVB radiation, but they are no substitute for covering the skin and avoiding sunlight. The sun protection factor (SPF, usually indicated in the preparation title) provides guidance on the degree of protection offered against UVB. It indicates the multiples of protection provided against burning, compared with unprotected skin. So a SPF of 15 should allow someone to remain 15 times longer in the sun without burning. Often, users don’t apply sufficient sunscreen product and the protection is lower than expected.
• Some manufacturers use a ( less precise ) star rating system to indicate the protection against UVA relative to protection against UVB for sunscreen products.
• Sunscreen preparations MAY cause allergic reactions, hard to predict – try a different one !
• They should be applied thickly and frequently ( 2 hourly ).
As a guide ( UK spring – autumn ):-
1. Fair / sensitive, facial and children’s skin – start with SPF 50, then reduce to 25(+) in UK ; always 50 in Philippines.
2. “ Normal “ skin – start with 25, then 15 in UK ; 25-50 then 15 in Philippines.
3. Dark skin – start with 25, then 15 in UK ; 25-50 then 15 in Philippines.
On a positive note :-
• Even if you’re worried about a skin lesion which may be new, increasing in size, and pigmented, by all means see a doctor who may recommend removal as a precaution. Every such lesion is routinely sent to a pathologist for microscopic examination. Of the very many such lesions excised, only a small proportion are cancer ( most commonly " rodent ulcer " ).
• Even among the pigmented lesions removed, by far the majority are benign ( non cancerous ) ; malignant melanoma is relatively rare even in the UK.