If dermatology experts could recommend only one anti-aging product, most would choose sunscreen. UV is the biggest cause of skin aging (photoaging) and is directly linked to skin cancer.
The two types of UV
UVA (320–400nm)
- Penetrates deep into the dermis and destroys collagen
- The main culprit behind wrinkles, loss of elasticity, and pigmentation (melasma, spots)
- Passes through clouds and glass; must be avoided 365 days a year
- Protection level shown by the PA rating, separate from SPF
UVB (280–320nm)
- Absorbed at the skin surface (epidermis)
- Linked to sunburn, redness, and skin cancer
- Strongest at midday in summer and on clear days
- Protection level shown by the SPF rating
What SPF and PA mean
SPF (Sun Protection Factor)
The UVB protection rating. If skin reddens in 10 minutes without sunscreen, applying SPF30 means the same amount of UVB reaches the skin over 30 × 10 = 300 minutes.
- Daily: SPF30–50
- Outdoor activity/swimming: SPF50+
PA (Protection Grade of UVA)
A UVA protection grade that originated in Japan.
- PA+: low protection
- PA++: moderate
- PA+++: high
- PA++++: highest (current maximum grade)
European products use PPD and the UVA circle mark.
The two types of sunscreen
Chemical (organic) filters
- Absorb UV and convert it to heat
- Main ingredients: avobenzone, oxybenzone, ecamsule
- Pros: light, no white cast
- Cons: some ingredients can irritate; take effect 20–30 minutes after application
Physical (inorganic) filters
- Reflect/scatter UV
- Main ingredients: zinc oxide, titanium dioxide
- Pros: immediate protection, low irritation (good for sensitive skin)
- Cons: white cast, heavy texture
These days many hybrid sunscreens combine both methods to balance the pros and cons.
The most common mistake: applying too little
Research shows most people apply only 20–50% of the recommended amount. The standard for the whole face is 2mg/cm² — about 1/4 teaspoon (1.2–1.5ml, roughly one fingertip segment) for an adult face.
Under-applying drops SPF50's real protection to around SPF10–15.
How to use sunscreen properly
- Last step of your routine: Apply last, over moisturizer (before makeup)
- Enough amount: Generously over the whole face, including ears, neck, and décolletage
- Reapply every 2–3 hours: Especially during outdoor activity. Use powder- or mist-type sunscreens
- Chemical filters: Apply 20–30 minutes before going out
- Year-round use: Even on cloudy days, UVA is 90% present and passes through glass
Extra sunscreen tips
- Let basic products and sunscreen absorb fully before layering (to prevent pilling)
- If one layer of sunscreen isn't enough, supplement with a cushion or foundation that has UV protection
- On days you don't want to apply sunscreen, even a BB cream or tinted moisturizer with SPF15+ helps
Consistent sun protection from your 20s reduces cumulative skin damage and produces a clearly different skin condition in your 40s–50s.