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34,000+ cities tracked 5 skin dimensions per city 12-mo stress calendar

Mosaique · Annual Report · 2025

World Skin
Stress Index

Which cities are hardest on your skin?

We scored every city and town in our database — 32,444 destinations across 240 countries — on UV intensity, air quality, humidity extremes, temperature, and altitude, then ranked them by the cumulative annual burden they place on human skin.

32,444

Cities ranked

5

Stress factors

240

Countries

8

Regions covered

The hardest cities on earth for skin

Three destinations that demand
the most from your skin

These cities score 9/10 — the highest in our entire 32,444-city index. All three combine
extreme UV, extreme heat, extreme aridity, and elevated pollution simultaneously. There
is no single culprit. That's precisely what makes them so demanding.

#35

Kuwait City

Kuwait

9/10 Extreme

UV 11 · AQI 88 · Humidity 28% · Temp 107°F

Ranked #35 overall — 34 Sahel cities score 10/10 above it — but Kuwait City is the most demanding travel destination in the index. Three simultaneous extremes: UV 11, AQI 88, and humidity below 30% at 107°F. No standard skincare protocol holds up here without significant reformulation.

#35

Riyadh

Saudi Arabia

9/10 Extreme

UV 11 · AQI 82 · Humidity 24% · Temp 104°F

At 24% average humidity, Riyadh is among the driest major cities in the index. Combined with UV 11, AQI 82, and 612m altitude, the skin barrier faces near-constant TEWL, oxidative stress, and photodamage simultaneously. Tied at rank #35 with all 9/10 cities.

#35

Khartoum

Sudan

9/10 Extreme

UV 11 · AQI 88 · Humidity 22% · Temp 100°F

Khartoum stacks every heat-and-aridity factor simultaneously. With average humidity of 22%, skin begins losing moisture without active humectant replenishment within hours of exposure. Ranked #35 overall — immediately behind the Sahel cities that score 10/10.

The kindest cities for your skin

Three destinations where
skin can breathe

These cities score 0 across all six factors — no meaningful UV, pollution, humidity extreme, heat,
altitude, or cold dryness. Ranked #31,459 of 32,444 — tied with 985 other temperate-climate cities
at the bottom of the index.

#31,459

Berlin

Germany

0/10 Low

UV 4 · AQI 38 · Humidity 72% · Temp 52°F

Ranked at the bottom among 32,444 cities — tied with 985 others at 0/10. Berlin scores zero across all six factors: negligible UV, clean air, balanced humidity, mild temperatures, near sea level. Your existing routine holds up unchanged.

#31,459

Zagreb

Croatia

0/10 Low

UV 4 · AQI 35 · Humidity 72% · Temp 52°F

Zagreb sits at 122m with clean Central European air, balanced humidity, and UV too low to drive photodamage at typical exposure. One of the most skin-neutral capital cities in the index — tied at #31,459 alongside Berlin and Zurich.

#31,459

Zurich

Switzerland

0/10 Low

UV 4 · AQI 25 · Humidity 72% · Temp 54°F

Zurich's pristine Alpine air (AQI 25 — among the cleanest in the index), low UV, and stable humidity produce zero stress points. One of the few cities where a minimalist routine genuinely suffices year-round. Tied at rank #31,459.

All 32,444 cities ranked

The complete 2025 ranking

Ranked by annual composite skin stress score (0–10). Filter by region, toggle to travel destinations
only, search by city or country. Click any row to expand the factor breakdown.

Showing 5 of 32,444 cities

#	City	Stress Score	UV	AQI	Humidity	Temp	Prep	Primary Drivers
1	Sikasso Mali	10/10	11	112	20%	98°F	Significant	Extreme heat; AC everywhere; UV critical; hard water; desert
1	Moundou Chad	10/10	11	125	20%	98°F	Significant	Extreme heat; AC everywhere; UV critical; hard water; desert
1	Sarh Chad	10/10	11	125	20%	98°F	Significant	Extreme heat; AC everywhere; UV critical; hard water; desert
2	Bougouni Mali	10/10	11	112	20%	98°F	Significant	Extreme heat; AC everywhere; UV critical; hard water; desert
2	Kelo Chad	10/10	11	125	20%	98°F	Significant	Extreme heat; AC everywhere; UV critical; hard water; desert

#	City	Stress Score	UV	AQI	Humidity	Temp	Prep	Primary Drivers
0		1/10			%	°F

Free · All 32,444 cities

Get your destination's
full skin advisory

The index tells you how cities rank. The full tool tells you exactly what to do — routine adjustments, product recommendations, a prep timeline, and a 12-month skin stress calendar for your specific destination.

Six findings from 32,444 cities

What the data reveals

Sahel Triple Threat

34 cities outrank every Gulf destination

Sikasso, Moundou, Sarh, and 31 more Sahel cities score 10/10 — above Kuwait City and Riyadh. The Sahel fires five factors simultaneously: UV 11, AQI 112–125, humidity below 20%, temperatures at 98°F. Kuwait City sits at rank #35, not #1. Enable "Travel Destinations" to see only holiday-relevant rankings.

The Andean UV Arc

The corridor no sunscreen label warns about

La Paz (3,640m), Cusco (3,400m), Quito (2,850m), and Bogotá (2,640m) form a 3,000-mile UV-amplified band down South America's spine. UV intensity rises ~10% per 1000m — La Paz receives nearly 40% more UV energy at ground level than a comparable sea-level city. SPF ratings are calibrated for sea level; they underperform at altitude.

South Asia Pollution Corridor

A 600-million-person barrier damage zone

Lahore (AQI 145), Delhi (130), Dhaka (168), and Chattogram (110) form a near-continuous band of critical air quality. At these levels, PM2.5 and ground ozone actively degrade the skin barrier year-round. Barrier-support actives — ceramides, niacinamide, antioxidants — move from optional to essential in this corridor.

Cold Dryness — New Factor

Why Montreal was always undercounted

Standard indices gave Montreal 0/10. Our sixth factor — cold-season heating dryness — corrects this. Indoor air in northern winters collapses to 15–20% relative humidity, lower than the Sahara on many days. Ulaanbaatar gains two full points. Oslo, Helsinki, Stockholm, and Moscow all move up. Cold climates are not gentle on the skin barrier.

East Africa UV Belt

The highlands hit harder than the coast

Nairobi (UV 12, 1,795m), Kigali (UV 12, 1,567m), Addis Ababa (UV 12, 2,355m), and Kampala (UV 12, 1,190m) cluster near the equator at altitude. UV here exceeds Dubai despite moderate AQI and balanced humidity. The African sun warning applies most acutely in the highland interior, not on the Indian Ocean coast.

The Maldives Paradox

UV 12, AQI 5 — the world's cleanest threat

The Maldives carries the index's highest UV alongside its lowest AQI. No pollution, balanced humidity, no altitude — photodamage is the only story. It scores 4/10: lower than Istanbul, higher than Barcelona. Single-axis extremes look moderate when averaged across six dimensions. Know your specific risk, not just the headline number.

Annual compilation · WSSI SIX-FACTOR MODEL · Edition 01

World Skin
Stress Index

Which cities are hardest on your skin?

300 destinations, each with one position from 1 to 300. Every score on this page is the WSSI six-factor score, calculated exactly as the full index calculates it, on the readings the index holds. Where destinations tie — and many do — they are separated by how far each one sits past the thresholds it crossed.

300

Destinations

6

Factors

0–9

Score range

8

Regions

01–08 · Heaviest load

Heaviest load

Desert sun, heat and dry air stack here, and the top of this band is genuinely crowded: nine destinations share the highest score in the set.

293–300 · Lightest load

Lightest load

Weak sun, clean air, moderate moisture. Cold-season dryness is scored here, so temperate winters carry a point rather than passing unrecorded.

Search city or country

Methodology

How a score is built

Six factors, each scored in whole points against fixed thresholds. A destination can reach 14. Across these 300 the observed range is 0 to 9.

UV: 1 point at index 5, 2 at 8, 3 at 11.
AIR: 1 point at AQI 40, 2 at 65, 3 at 100.
MOIST: 1 point above 75% or below 38% relative humidity, 2 above 82% or below 30%. Dry and damp extremes both count.
HEAT: 1 point above 85°F, 2 above 95°F.
ALT: 1 point above 800m, 2 above 2000m. Altitude scores on its own line.
COLD: 1 point below 50°F, 2 below 32°F.

Whole points mean ties. Sixty-seven destinations score 5; forty-nine score 2. A ladder of 300 distinct positions cannot come from the score alone.

Ties break on threshold proximity. For each factor, a destination is measured on how far past its cleared cutoff it sits, as a fraction of the distance to the next cutoff. Those six fractions are summed and used only to order destinations that already share a score. The score always outranks the fraction. Where two destinations match on both, the larger settlement is listed first, then alphabetically.

Water hardness is not scored. It carries three categories, which cannot separate 300 destinations. It sits on each card as an advisory reading.

Reading the index

What this ranking carries

The score is reproducible: the same six rules, the same thresholds, the same inputs as the full index. Anyone can recompute it. The separation between tied destinations is a stated convention, not a measurement.

Read the bands, not the decimals. A gap of one position inside a shared score reflects threshold proximity, which is a tie-break rule rather than evidence that one destination is harder on skin than the next. Positions that sit in different score bands are meaningfully apart. Positions inside the same band are a neighborhood.

Readings are carried unchanged. Every environmental value on these cards is the figure held in the source index, reproduced without adjustment or rescaling, so a score calculated here and a score calculated there always agree.

Four entries are scored through a principal city. Bali, Maldives, Jeju Island and Tenerife are regions rather than settlements. Each is scored on its principal city, which is named on the card.

Ten entries were added to hold the count at 300. Nine leisure destinations in the previous edition have no record in the source index, and Penang duplicated George Town. All ten were removed. Their places were filled from the highest-scoring destinations in the index that were not already listed. These are marked on the card.

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