Acute, intense exposure
The immediate consequence is sunburn (erythema).
The skin's natural photoprotective mechanisms require time
to become fully effective.
Today, sun exposure is often intense (lasting many hours) and
occasional (limited to a weekend or a few days), frequently taking
place in tropical or subtropical regions where solar irradiance is particularly high.
As a consequence, the skin experiences a continuous “stop-and-go”
pattern of exposure. Paradoxically, its natural defence mechanisms reach their
maximum efficiency only after the sunny holiday has ended.
Another important factor is the widespread cult of tanning,
which encourages prolonged and excessive exposure to sunlight in the pursuit
of a deep tan.
Chronic exposure over many years
Sun-exposed areas may develop photoaging and, in some individuals, skin cancers.