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34,000+ cities tracked 5 skin dimensions per city 12-mo stress calendar
Mosaique ยท Annual Report ยท 2025
World Skin
Stress Index
Which cities are hardest on your skin?
We scored every city and town in our database โ 32,444 destinations across 240 countries โ 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 โ 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
UV 11 ยท AQI 88 ยท Humidity 28% ยท Temp 107ยฐF
Ranked #35 overall โ 34 Sahel cities score 10/10 above it โ but Kuwait City is the most demanding travel destination in the index. Three simultaneous extremes: UV 11, AQI 88, and humidity below 30% at 107ยฐF. No standard skincare protocol holds up here without significant reformulation.
#35
Riyadh
Saudi Arabia
UV 11 ยท AQI 82 ยท Humidity 24% ยท Temp 104ยฐF
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
UV 11 ยท AQI 88 ยท Humidity 22% ยท Temp 100ยฐF
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 โ 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 โ no meaningful UV, pollution, humidity extreme, heat,
altitude, or cold dryness. Ranked #31,459 of 32,444 โ tied with 985 other temperate-climate cities
at the bottom of the index.
#31,459
Berlin
Germany
UV 4 ยท AQI 38 ยท Humidity 72% ยท Temp 52ยฐF
Ranked at the bottom among 32,444 cities โ 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
UV 4 ยท AQI 35 ยท Humidity 72% ยท Temp 52ยฐF
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 โ tied at #31,459 alongside Berlin and Zurich.
#31,459
Zurich
Switzerland
UV 4 ยท AQI 25 ยท Humidity 72% ยท Temp 54ยฐF
Zurich's pristine Alpine air (AQI 25 โ 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 (0โ10). 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% | 98ยฐF | Significant | Extreme heat; AC everywhere; UV critical; hard water; desert |
| 1 | Moundou Chad | 10/10 | 11 | 125 | 20% | 98ยฐF | Significant | Extreme heat; AC everywhere; UV critical; hard water; desert |
| 1 | Sarh Chad | 10/10 | 11 | 125 | 20% | 98ยฐF | Significant | Extreme heat; AC everywhere; UV critical; hard water; desert |
| 2 | Bougouni Mali | 10/10 | 11 | 112 | 20% | 98ยฐF | Significant | Extreme heat; AC everywhere; UV critical; hard water; desert |
| 2 | Kelo Chad | 10/10 | 11 | 125 | 20% | 98ยฐF | Significant | Extreme heat; AC everywhere; UV critical; hard water; desert |
Free ยท 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 โ 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 โ above Kuwait City and Riyadh. The Sahel fires five factors simultaneously: UV 11, AQI 112โ125, humidity below 20%, temperatures at 98ยฐF. 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 Bogotรก (2,640m) form a 3,000-mile UV-amplified band down South America's spine. UV intensity rises ~10% per 1000m โ 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 โ ceramides, niacinamide, antioxidants โ move from optional to essential in this corridor.
Cold Dryness โ New Factor
Why Montreal was always undercounted
Standard indices gave Montreal 0/10. Our sixth factor โ cold-season heating dryness โ corrects this. Indoor air in northern winters collapses to 15โ20% 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 โ the world's cleanest threat
The Maldives carries the index's highest UV alongside its lowest AQI. No pollution, balanced humidity, no altitude โ 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 ยท WSSI SIX-FACTOR MODEL ยท Edition 01
2025 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 โ and many do โ they are separated by how far each one sits past the thresholds it crossed.
300
Destinations
6
Factors
0โ9
Score range
8
Regions
01โ08 ยท 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.
293โ300 ยท 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.
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 85ยฐF, 2 above 95ยฐF.
- ALT
- 1 point above 800m, 2 above 2000m. Altitude scores on its own line.
- COLD
- 1 point below 50ยฐF, 2 below 32ยฐF.
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.
Kuwait City
Kuwait ยท 2025Extreme ยท ranked #35 of 32,444
Method ยท World Skin Stress Index
How a city gets its number
Every score in the index is a sum. Five measurements go in. Six line items are checked against fixed thresholds. Each one adds a whole number of points, and the points add up to the score.
There are no weightings behind the curtain and no model you have to take on faith. You can reproduce any city's number with a pen.
score = UV + air quality + humidity + heat + altitude + cold dryness
Five inputs, six line items. Heat and cold dryness read the same thermometer from opposite ends, so a city can trigger one or the other and never both. UV and air quality carry up to 3 points each. The remaining four cap at 2.
Build a score
Move the readings. Watch the points post.
The tick marks under each track are the exact thresholds. Nothing is interpolated and nothing is rounded, so a city sitting one unit below a threshold scores the same as a city far below it. Load a real city to see how different climates arrive at the same total by different routes.
Pick a city above, or move the sliders yourself.
The thresholds
Every cutoff, written down
All six line items in full. Readings are annual means for each city. A factor contributes nothing until its first cutoff is met.
| Line item | Ceiling | +1 point | +2 points | +3 points |
|---|---|---|---|---|
| Ultraviolet | up to 3 | UV 5 and above | UV 8 and above | UV 11 and above |
| Air quality | up to 3 | AQI 40 and above | AQI 65 and above | AQI 100 and above |
| Humidity | up to 2 | below 38% or above 75% | below 30% or above 82% | not reachable |
| Heat | up to 2 | above 85ยฐF | above 95ยฐF | not reachable |
| Altitude | up to 2 | above 800 m | above 2,000 m | not reachable |
| Cold dryness | up to 2 | below 50ยฐF | below 32ยฐF | not reachable |
The five bands
What the number is called
Bands group the eleven possible scores into five labels. They carry no extra arithmetic; they are a reading aid for the same whole number. Counts below cover the 32,444 scored cities in the current 2025 index.
0 โ 2
Low
9,021 cities
27.8% of the index
3 โ 4
Moderate
9,535 cities
29.4% of the index
5 โ 6
High
8,999 cities
27.7% of the index
7 โ 8
Very High
4,729 cities
14.6% of the index
9 โ 10
Extreme
160 cities
0.5% of the index
How rank follows
Ties share a rank, and most cities tie
Rank is not a separate judgment. It falls straight out of the score: a city's rank is the number of cities scoring above it, plus one.
Because the score is a whole number with only eleven possible values, thousands of cities share each one. All 34 cities scoring 10 are ranked #1 together. The next rank is #35.
This is why Kuwait City sits at #35 rather than #1 while still being the highest-scoring city most travelers will ever book a flight to.
| Score | Cities | Shared rank |
|---|
Read this before you cite it
What the score does not tell you
Annual means
Every reading is an annual average. A city with a mild yearly mean can still be punishing in August. The index ranks places, not travel dates. For a specific window, use the destination tool.
Not clinical
This is a measure of environmental load, not a dermatological assessment. It describes conditions a city presents, not what any individual's skin will do in response. Skin type, genetics, medication, and time outdoors all sit outside the model.
Same score, different cause
A 5 built from altitude and UV in Cusco has almost nothing in common with a 5 built from pollution in Delhi. The headline number tells you how much; only the line items tell you what. Always open the breakdown.
Outside the score
Water hardness is tracked in the destination advisory but sits outside this arithmetic. It appears as a qualitative flag, never as points.
Data coverage
Coverage is not uniform across the 32,444 scored cities. 2,248 records carry an elevation of zero, and some of those are missing values rather than true sea level, which can hold a city one point below where complete data would place it. Where a city's line items look wrong to you, they may be.
No score at all
A further 128 destinations sit in the directory with no score. Santorini, Mykonos, Bora Bora, Roatรกn, the Galรกpagos and Banff are among them. No UV, air quality, humidity, temperature or elevation reading exists for them in our source data, so nothing has been estimated on their behalf and they are left out of the ranking. They stay searchable and keep their island and destination flags. The directory therefore holds 32,572 entries, of which 32,444 carry a score.
Flags are not points
The directory can filter to travel destinations, island cities or pilgrimage sites. Those flags change which rows you see, never the arithmetic. Two cities with identical readings score the same whether or not either is flagged, and the flags carry no weight in the sum.
Ceiling
The arithmetic could in principle reach 12. No city in the 2025 index does. The highest observed total is 10, which is why the scale is published as 0 to 10.
Now go check our arithmetic against a city you know.
Climate type -
0
Water hardness -
Skin Stress Index
โโ
Environmental load
0ยฐF
Temperature
Cold
0%
Humidity
Low
UV 0
Sun Exposure
Low
AQI 0
Air Quality
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What this climate will do โ and what to do about it
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Environmental load
0ยฐF
Temperature
Cold
0%
Humidity
Low
UV 0
Sun Exposure
Low
AQI 0
Air Quality
GoodWhat to expect
What this climate will do โ and what to do about it
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Why this happens
What to Do:
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