Intrinsic vs Extrinsic Ageing
Intrinsic ageing is the biologically programmed decline in skin function — driven by genetics, telomere shortening, and gradual reduction in fibroblast activity. It's largely unmodifiable.
Extrinsic ageing (photoageing, exposomic ageing) is environmentally-driven damage — and accounts for an estimated 80% of visible facial ageing. This is the part you can intervene in.
The Four Exposomic Threats
1. UV Radiation
The dominant extrinsic ageing factor. UVB causes direct DNA damage (cyclobutane pyrimidine dimers); UVA penetrates deeper, generating reactive oxygen species that degrade collagen via MMP activation. Cumulative UV exposure creates the visible characteristics of photoageing: deep wrinkles, lentigines (sun spots), loss of elasticity, telangiectasia.
2. Air Pollution (Particulate Matter, Ozone)
Ultrafine particulate matter (PM2.5 and PM0.1) can penetrate the skin barrier and generate intracellular ROS. Traffic-related air pollution (polycyclic aromatic hydrocarbons, nitrogen dioxide) has been associated with accelerated skin ageing, increased hyperpigmentation, and acne exacerbation in epidemiological studies. Ozone oxidises squalene in the skin lipidome, generating pro-inflammatory aldehydes.
3. HEV Blue Light
400–500nm light from screens and LED sources generates melanogenesis and ROS. Less damaging per unit than UV, but cumulative from 8–12 hours of daily screen exposure. See the full Digital Exposome guide.
4. Tobacco Smoke
Smoking causes vasoconstriction (reducing nutrient delivery), generates massive oxidative stress, and directly inhibits collagen synthesis via MMP upregulation. Smokers' skin shows characteristic patterns: perioral lines, sallow colour, accelerated skin thinning.
The Anti-Exposome Protocol
| Intervention | Target | Evidence |
|---|---|---|
| SPF 50+ broad-spectrum (daily) | UV (UVA + UVB) | Very strong — prevents photoageing, cancer, and pigmentation |
| Tinted SPF with iron oxides | UV + HEV | Strong |
| Vitamin C + E + Ferulic (AM) | Pollution + UV-generated ROS | Strong — antioxidant shield before daily exposure |
| Retinoids (PM) | Reversal of existing UV damage; collagen synthesis | Very strong |
| Niacinamide | Pollution pigmentation + barrier support | Moderate-strong |
| Quit smoking | Vasoconstriction, oxidative stress | Very strong — irreplaceable |
The most evidence-backed anti-ageing routine: Morning antioxidant serum (Vitamin C + E + Ferulic) + SPF 50+ with iron oxides. Evening retinoid + ceramide moisturiser. These four steps address all four exposomic threats. Every other step is incremental.
See the complete biology in Epigenetics of Skin Aging and the ingredient detail in Retinoids.