SeasonMap

Winter smog, month by month around the world

Coal smoke and a valley inversion; the air, not the cold, is the problem.

This is a warning page, not a recommendation. Winter smog covers 38 destinations on SeasonMap; the months below are the ones in which the risk window is open — most weeks in them pass quietly, and the score beside each place is still the ordinary climate score, hazard and all.

← All seasons · The world's calendar

When it is on

Number of destinations with winter smog on in that month. Windows move a little each year.

Winter smog in January

  1. 🇧🇩 Dhaka, BangladeshDry-season air · 15 Nov – 28 FebBrick kilns fire through the dry months, the construction dust never stops, and the city trades places with Delhi and Lahore at the top of the daily air rankings.93climate
  2. 🇹🇼 Kaohsiung, TaiwanWinter air-quality season · 1 Oct – 31 Mar (usually)The rain stops, the wind drops and the petrochemical belt on the north side has nowhere to go.87climate
  3. 🇮🇳 Varanasi, IndiaPost-Diwali smog · 25 Oct – 10 Feb (usually)Stubble burning upwind, firecrackers and a cold air trap put the plains under a brown haze from Diwali onward.86climate
  4. 🇹🇼 Taichung, TaiwanAutumn and winter haze · 15 Oct – 31 Mar (usually)Once the summer winds drop, the mountains behind the city stop the air moving and central Taiwan's industry and power stations sit in it.86climate
  5. 🇮🇳 Agra, IndiaWinter smog season · 1 Nov – 31 Jan (usually)Cold still air over the Doab holds in field smoke, brick kilns and traffic, and the monument can vanish from the far end of its own garden before ten.82climate
  6. 🇵🇰 Lahore, PakistanSmog season · 15 Oct – 31 Jan (usually)The province declares a smog season and acts on it: schools shut, offices go part-remote, brick kilns and building sites stop.74climate
  7. 🇵🇰 Islamabad, PakistanWinter haze from the plains · 1 Nov – 15 Jan (usually)The Punjab smog does not stop at the motorway.69climate
  8. 🇨🇳 Chengdu, ChinaWinter smog · 15 Nov – 28 FebThe basin holds its own air all winter under an inversion.67climate
  9. 🇮🇷 Tehran, IranWinter inversion smog · 15 Nov – 28 Feb (usually)Cold air traps the traffic exhaust against the mountains for days at a time and the government closes schools and offices when it gets bad.64climate
  10. 🇦🇱 Tirana, AlbaniaWinter air pollution · 15 Nov – 28 FebOld diesel cars in a basin ringed by hills, plus wood heating, and the winter readings climb well past what the city's reputation for mild weather suggests.63climate
  11. 🇨🇳 Shanghai, ChinaWinter haze · 15 Nov – 28 Feb (usually)Still, cold weeks trap particulates over the delta and the skyline goes flat grey for days until a front clears it.62climate
  12. 🇮🇹 Turin, ItalyPo valley smog season · 1 Oct – 31 MarThe city sits in a bowl with the Alps on three sides, and winter inversions trap particulates for days.62climate
  13. 🇮🇹 Milan, ItalyPo valley smog season · 15 Nov – 28 Feb (usually)The valley sits under the Alps with nowhere for the air to go, so still cold weeks stack particulate up until the region bans the oldest cars.60climate
  14. 🇨🇳 Pingyao, ChinaHeating-season smog · 15 Nov – 15 Mar (usually)Shanxi is China's coal province and the central heating goes on in the middle of November.59climate
  15. 🇧🇬 Plovdiv, BulgariaWinter smog · 1 Nov – 10 Mar (usually)Wood and coal stoves in the surrounding villages, plus an inversion that traps everything over the Thracian plain, give Plovdiv some of the worst winter particulate readings in the EU.58climate
  16. 🇨🇳 Xi'an, ChinaWinter smog · 15 Nov – 28 FebThe Guanzhong basin traps its air under the Qinling mountains all winter, and Xi'an posts some of the worst readings in the country.57climate
  17. 🇧🇦 Banja Luka, Bosnia and HerzegovinaWinter heating smog · 15 Nov – 28 Feb (usually)Solid-fuel heating plus a valley inversion parks the smoke over the city on still winter days, and January is reliably the worst of it.56climate
  18. 🇲🇰 Skopje, North MacedoniaWinter air pollution · 1 Nov – 28 FebHousehold heating and traffic under a valley inversion make this one of the worst-affected capitals in Europe, and schools have been closed over it.55climate
  19. 🇹🇷 Ankara, TurkeyWinter inversion · 15 Nov – 28 Feb (usually)The city sits in a bowl and cold, still weather traps household heating smoke in it for days at a time.55climate
  20. 🇷🇸 Belgrade, SerbiaWinter smog · 1 Nov – 15 Mar (usually)Household coal and wood, old cars and a windless inversion over the confluence put Belgrade near the top of the world air-quality tables on the worst January mornings.54climate
  21. 🇷🇸 Niš, SerbiaWinter heating smog · 1 Dec – 28 Feb (usually)The same basin that traps the summer heat traps coal smoke from December to February, and the readings go from ordinary to genuinely unhealthy.52climate
  22. 🇺🇸 Boise, United StatesWinter inversion · 15 Nov – 15 Feb (usually)Cold air pools in the U-shaped valley under a warm lid and the wood smoke and traffic exhaust stay with it, sometimes for weeks.51climate
  23. 🇷🇸 Novi Sad, SerbiaWinter air pollution · 15 Nov – 28 FebCold, still days over the Pannonian flat trap household heating smoke and the city regularly logs some of the worst readings in Europe.51climate
  24. 🇧🇬 Sofia, BulgariaWinter smog · 1 Nov – 10 Mar (usually)The city sits in a basin under Vitosha and the cold air does not move; wood and coal heating in the outer districts then fills it.49climate
  25. 🇩🇪 Stuttgart, GermanyValley inversion air · 15 Nov – 28 Feb (usually)The city centre sits in a steep bowl with almost no through wind, which is why it spent years as Germany's worst spot for traffic particulates and still traps its own air on still winter days.49climate

…and 10 more in January.

What's on around the world in January →

Winter smog in February

  1. 🇹🇼 Kaohsiung, TaiwanWinter air-quality season · 1 Oct – 31 Mar (usually)The rain stops, the wind drops and the petrochemical belt on the north side has nowhere to go.90climate
  2. 🇮🇳 Varanasi, IndiaPost-Diwali smog · 25 Oct – 10 Feb (usually)Stubble burning upwind, firecrackers and a cold air trap put the plains under a brown haze from Diwali onward.89climate
  3. 🇹🇼 Taichung, TaiwanAutumn and winter haze · 15 Oct – 31 Mar (usually)Once the summer winds drop, the mountains behind the city stop the air moving and central Taiwan's industry and power stations sit in it.88climate
  4. 🇧🇩 Dhaka, BangladeshDry-season air · 15 Nov – 28 FebBrick kilns fire through the dry months, the construction dust never stops, and the city trades places with Delhi and Lahore at the top of the daily air rankings.84climate
  5. 🇦🇱 Tirana, AlbaniaWinter air pollution · 15 Nov – 28 FebOld diesel cars in a basin ringed by hills, plus wood heating, and the winter readings climb well past what the city's reputation for mild weather suggests.75climate
  6. 🇨🇳 Chengdu, ChinaWinter smog · 15 Nov – 28 FebThe basin holds its own air all winter under an inversion.73climate
  7. 🇮🇷 Tehran, IranWinter inversion smog · 15 Nov – 28 Feb (usually)Cold air traps the traffic exhaust against the mountains for days at a time and the government closes schools and offices when it gets bad.70climate
  8. 🇧🇬 Plovdiv, BulgariaWinter smog · 1 Nov – 10 Mar (usually)Wood and coal stoves in the surrounding villages, plus an inversion that traps everything over the Thracian plain, give Plovdiv some of the worst winter particulate readings in the EU.68climate
  9. 🇨🇳 Xi'an, ChinaWinter smog · 15 Nov – 28 FebThe Guanzhong basin traps its air under the Qinling mountains all winter, and Xi'an posts some of the worst readings in the country.68climate
  10. 🇮🇹 Turin, ItalyPo valley smog season · 1 Oct – 31 MarThe city sits in a bowl with the Alps on three sides, and winter inversions trap particulates for days.68climate
  11. 🇲🇰 Skopje, North MacedoniaWinter air pollution · 1 Nov – 28 FebHousehold heating and traffic under a valley inversion make this one of the worst-affected capitals in Europe, and schools have been closed over it.68climate
  12. 🇷🇸 Belgrade, SerbiaWinter smog · 1 Nov – 15 Mar (usually)Household coal and wood, old cars and a windless inversion over the confluence put Belgrade near the top of the world air-quality tables on the worst January mornings.67climate
  13. 🇷🇸 Niš, SerbiaWinter heating smog · 1 Dec – 28 Feb (usually)The same basin that traps the summer heat traps coal smoke from December to February, and the readings go from ordinary to genuinely unhealthy.67climate
  14. 🇨🇳 Shanghai, ChinaWinter haze · 15 Nov – 28 Feb (usually)Still, cold weeks trap particulates over the delta and the skyline goes flat grey for days until a front clears it.66climate
  15. 🇮🇹 Milan, ItalyPo valley smog season · 15 Nov – 28 Feb (usually)The valley sits under the Alps with nowhere for the air to go, so still cold weeks stack particulate up until the region bans the oldest cars.66climate
  16. 🇹🇷 Ankara, TurkeyWinter inversion · 15 Nov – 28 Feb (usually)The city sits in a bowl and cold, still weather traps household heating smoke in it for days at a time.66climate
  17. 🇷🇸 Novi Sad, SerbiaWinter air pollution · 15 Nov – 28 FebCold, still days over the Pannonian flat trap household heating smoke and the city regularly logs some of the worst readings in Europe.65climate
  18. 🇧🇦 Banja Luka, Bosnia and HerzegovinaWinter heating smog · 15 Nov – 28 Feb (usually)Solid-fuel heating plus a valley inversion parks the smoke over the city on still winter days, and January is reliably the worst of it.65climate
  19. 🇧🇬 Sofia, BulgariaWinter smog · 1 Nov – 10 Mar (usually)The city sits in a basin under Vitosha and the cold air does not move; wood and coal heating in the outer districts then fills it.64climate
  20. Pristina, KosovoWinter air pollution · 1 Nov – 28 FebTwo lignite power stations sit just outside the city and household heating adds to them, and cold still nights trap the lot in the basin.64climate
  21. 🇨🇳 Pingyao, ChinaHeating-season smog · 15 Nov – 15 Mar (usually)Shanxi is China's coal province and the central heating goes on in the middle of November.64climate
  22. 🇧🇦 Sarajevo, Bosnia and HerzegovinaValley inversion smog · 1 Nov – 28 FebCold air settles in the bowl of the valley and holds coal and wood smoke over the city for days at a time; the readings regularly rank among the world's worst.63climate
  23. 🇩🇪 Stuttgart, GermanyValley inversion air · 15 Nov – 28 Feb (usually)The city centre sits in a steep bowl with almost no through wind, which is why it spent years as Germany's worst spot for traffic particulates and still traps its own air on still winter days.62climate
  24. 🇺🇸 Boise, United StatesWinter inversion · 15 Nov – 15 Feb (usually)Cold air pools in the U-shaped valley under a warm lid and the wood smoke and traffic exhaust stay with it, sometimes for weeks.61climate
  25. 🇨🇳 Beijing, ChinaWinter smog days · 15 Nov – 28 Feb (usually)The heating season and a still, cold high can pin a grey lid over the city for days; it is far better than it was a decade ago, but the bad spells still come in runs of three or four days.59climate

…and 7 more in February.

What's on around the world in February →

Winter smog in March

  1. 🇹🇼 Kaohsiung, TaiwanWinter air-quality season · 1 Oct – 31 Mar (usually)The rain stops, the wind drops and the petrochemical belt on the north side has nowhere to go.80climate
  2. 🇹🇼 Taichung, TaiwanAutumn and winter haze · 15 Oct – 31 Mar (usually)Once the summer winds drop, the mountains behind the city stop the air moving and central Taiwan's industry and power stations sit in it.80climate
  3. 🇧🇬 Plovdiv, BulgariaWinter smog · 1 Nov – 10 Mar (usually)Wood and coal stoves in the surrounding villages, plus an inversion that traps everything over the Thracian plain, give Plovdiv some of the worst winter particulate readings in the EU.75climate
  4. 🇷🇸 Belgrade, SerbiaWinter smog · 1 Nov – 15 Mar (usually)Household coal and wood, old cars and a windless inversion over the confluence put Belgrade near the top of the world air-quality tables on the worst January mornings.74climate
  5. 🇮🇹 Turin, ItalyPo valley smog season · 1 Oct – 31 MarThe city sits in a bowl with the Alps on three sides, and winter inversions trap particulates for days.74climate
  6. 🇨🇳 Pingyao, ChinaHeating-season smog · 15 Nov – 15 Mar (usually)Shanxi is China's coal province and the central heating goes on in the middle of November.71climate
  7. 🇧🇬 Sofia, BulgariaWinter smog · 1 Nov – 10 Mar (usually)The city sits in a basin under Vitosha and the cold air does not move; wood and coal heating in the outer districts then fills it.70climate
  8. 🇰🇬 Bishkek, KyrgyzstanWinter smog · 1 Nov – 1 Mar (usually)Coal stoves in the private housing around the city plus an inversion in the bowl put Bishkek near the top of the world air-quality lists on winter mornings.68climate
  9. 🇵🇱 Wrocław, PolandWinter smog · 1 Nov – 10 Mar (usually)Coal and wood stoves still heat a lot of the old tenement stock, and a windless freeze puts the readings into the range that makes national news.67climate
  10. 🇵🇱 Kraków, PolandWinter smog · 1 Nov – 15 Mar (usually)Coal heating in the valley towns around the city and a cold inversion put the worst air of the year over Krakow between November and March.65climate
  11. 🇵🇱 Poznań, PolandWinter smog · 10 Nov – 5 Mar (usually)Solid-fuel stoves in the older districts and windless, freezing days push the air into the range Poland is known for.65climate
  12. 🇵🇱 Warsaw, PolandWinter smog · 1 Nov – 15 Mar (usually)Coal and wood heating in the surrounding towns plus a cold, still inversion give the city its worst air between November and March.64climate
  13. 🇵🇱 Łódź, PolandWinter smog · 1 Nov – 15 Mar (usually)Coal and wood stoves in the old tenement districts, plus still, cold air over a flat city, put the worst readings of the year here between November and March.64climate
  14. 🇵🇱 Zakopane, PolandWinter smog · 15 Nov – 15 Mar (usually)A resort at the foot of a national park with some of the worst winter air in Poland: coal stoves in the valley and no wind to move it.53climate

What's on around the world in March →

Winter smog in June

  1. 🇿🇦 Pretoria, South AfricaWinter haze in the valley · 1 Jun – 31 Aug (usually)Cold air settles between the ridges and holds smoke from veld fires and household coal under it, so the horizon browns out for weeks.88climate
  2. 🇿🇦 Johannesburg, South AfricaWinter haze over the Highveld · 1 Jun – 31 Aug (usually)Cold air traps smoke from veld fires, coal stoves and the industrial East Rand under an inversion, and the horizon goes brown for weeks.85climate
  3. 🇮🇩 Jakarta, IndonesiaDry-season smog · 15 Jun – 15 Oct (usually)Traffic, coal plants along the coast and no rain to clear it: Jakarta regularly ranks among the world's most polluted major cities in these months.65climate

What's on around the world in June →

Winter smog in July

  1. 🇿🇦 Pretoria, South AfricaWinter haze in the valley · 1 Jun – 31 Aug (usually)Cold air settles between the ridges and holds smoke from veld fires and household coal under it, so the horizon browns out for weeks.88climate
  2. 🇿🇦 Johannesburg, South AfricaWinter haze over the Highveld · 1 Jun – 31 Aug (usually)Cold air traps smoke from veld fires, coal stoves and the industrial East Rand under an inversion, and the horizon goes brown for weeks.85climate
  3. 🇮🇩 Jakarta, IndonesiaDry-season smog · 15 Jun – 15 Oct (usually)Traffic, coal plants along the coast and no rain to clear it: Jakarta regularly ranks among the world's most polluted major cities in these months.69climate

What's on around the world in July →

Winter smog in August

  1. 🇿🇦 Pretoria, South AfricaWinter haze in the valley · 1 Jun – 31 Aug (usually)Cold air settles between the ridges and holds smoke from veld fires and household coal under it, so the horizon browns out for weeks.93climate
  2. 🇿🇦 Johannesburg, South AfricaWinter haze over the Highveld · 1 Jun – 31 Aug (usually)Cold air traps smoke from veld fires, coal stoves and the industrial East Rand under an inversion, and the horizon goes brown for weeks.91climate
  3. 🇮🇩 Jakarta, IndonesiaDry-season smog · 15 Jun – 15 Oct (usually)Traffic, coal plants along the coast and no rain to clear it: Jakarta regularly ranks among the world's most polluted major cities in these months.70climate

What's on around the world in August →

Winter smog in September

  1. 🇮🇩 Jakarta, IndonesiaDry-season smog · 15 Jun – 15 Oct (usually)Traffic, coal plants along the coast and no rain to clear it: Jakarta regularly ranks among the world's most polluted major cities in these months.68climate

What's on around the world in September →

Winter smog in October

  1. 🇮🇹 Turin, ItalyPo valley smog season · 1 Oct – 31 MarThe city sits in a bowl with the Alps on three sides, and winter inversions trap particulates for days.78climate
  2. 🇵🇰 Lahore, PakistanSmog season · 15 Oct – 31 Jan (usually)The province declares a smog season and acts on it: schools shut, offices go part-remote, brick kilns and building sites stop.72climate
  3. 🇮🇳 Varanasi, IndiaPost-Diwali smog · 25 Oct – 10 Feb (usually)Stubble burning upwind, firecrackers and a cold air trap put the plains under a brown haze from Diwali onward.65climate
  4. 🇹🇼 Taichung, TaiwanAutumn and winter haze · 15 Oct – 31 Mar (usually)Once the summer winds drop, the mountains behind the city stop the air moving and central Taiwan's industry and power stations sit in it.64climate
  5. 🇮🇩 Jakarta, IndonesiaDry-season smog · 15 Jun – 15 Oct (usually)Traffic, coal plants along the coast and no rain to clear it: Jakarta regularly ranks among the world's most polluted major cities in these months.61climate
  6. 🇹🇼 Kaohsiung, TaiwanWinter air-quality season · 1 Oct – 31 Mar (usually)The rain stops, the wind drops and the petrochemical belt on the north side has nowhere to go.60climate

What's on around the world in October →

Winter smog in November

  1. 🇵🇰 Lahore, PakistanSmog season · 15 Oct – 31 Jan (usually)The province declares a smog season and acts on it: schools shut, offices go part-remote, brick kilns and building sites stop.91climate
  2. 🇵🇰 Islamabad, PakistanWinter haze from the plains · 1 Nov – 15 Jan (usually)The Punjab smog does not stop at the motorway.90climate
  3. 🇮🇳 Agra, IndiaWinter smog season · 1 Nov – 31 Jan (usually)Cold still air over the Doab holds in field smoke, brick kilns and traffic, and the monument can vanish from the far end of its own garden before ten.88climate
  4. 🇮🇳 Varanasi, IndiaPost-Diwali smog · 25 Oct – 10 Feb (usually)Stubble burning upwind, firecrackers and a cold air trap put the plains under a brown haze from Diwali onward.82climate
  5. 🇨🇳 Shanghai, ChinaWinter haze · 15 Nov – 28 Feb (usually)Still, cold weeks trap particulates over the delta and the skyline goes flat grey for days until a front clears it.78climate
  6. 🇨🇳 Chengdu, ChinaWinter smog · 15 Nov – 28 FebThe basin holds its own air all winter under an inversion.78climate
  7. 🇮🇷 Tehran, IranWinter inversion smog · 15 Nov – 28 Feb (usually)Cold air traps the traffic exhaust against the mountains for days at a time and the government closes schools and offices when it gets bad.78climate
  8. 🇨🇳 Pingyao, ChinaHeating-season smog · 15 Nov – 15 Mar (usually)Shanxi is China's coal province and the central heating goes on in the middle of November.78climate
  9. 🇹🇼 Taichung, TaiwanAutumn and winter haze · 15 Oct – 31 Mar (usually)Once the summer winds drop, the mountains behind the city stop the air moving and central Taiwan's industry and power stations sit in it.77climate
  10. 🇧🇩 Dhaka, BangladeshDry-season air · 15 Nov – 28 FebBrick kilns fire through the dry months, the construction dust never stops, and the city trades places with Delhi and Lahore at the top of the daily air rankings.75climate
  11. 🇹🇷 Ankara, TurkeyWinter inversion · 15 Nov – 28 Feb (usually)The city sits in a bowl and cold, still weather traps household heating smoke in it for days at a time.73climate
  12. 🇹🇼 Kaohsiung, TaiwanWinter air-quality season · 1 Oct – 31 Mar (usually)The rain stops, the wind drops and the petrochemical belt on the north side has nowhere to go.72climate
  13. 🇨🇳 Xi'an, ChinaWinter smog · 15 Nov – 28 FebThe Guanzhong basin traps its air under the Qinling mountains all winter, and Xi'an posts some of the worst readings in the country.71climate
  14. 🇧🇬 Plovdiv, BulgariaWinter smog · 1 Nov – 10 Mar (usually)Wood and coal stoves in the surrounding villages, plus an inversion that traps everything over the Thracian plain, give Plovdiv some of the worst winter particulate readings in the EU.70climate
  15. 🇦🇱 Tirana, AlbaniaWinter air pollution · 15 Nov – 28 FebOld diesel cars in a basin ringed by hills, plus wood heating, and the winter readings climb well past what the city's reputation for mild weather suggests.70climate
  16. 🇨🇳 Beijing, ChinaWinter smog days · 15 Nov – 28 Feb (usually)The heating season and a still, cold high can pin a grey lid over the city for days; it is far better than it was a decade ago, but the bad spells still come in runs of three or four days.67climate
  17. 🇲🇰 Skopje, North MacedoniaWinter air pollution · 1 Nov – 28 FebHousehold heating and traffic under a valley inversion make this one of the worst-affected capitals in Europe, and schools have been closed over it.67climate
  18. 🇧🇬 Sofia, BulgariaWinter smog · 1 Nov – 10 Mar (usually)The city sits in a basin under Vitosha and the cold air does not move; wood and coal heating in the outer districts then fills it.66climate
  19. 🇺🇸 Boise, United StatesWinter inversion · 15 Nov – 15 Feb (usually)Cold air pools in the U-shaped valley under a warm lid and the wood smoke and traffic exhaust stay with it, sometimes for weeks.66climate
  20. 🇷🇸 Belgrade, SerbiaWinter smog · 1 Nov – 15 Mar (usually)Household coal and wood, old cars and a windless inversion over the confluence put Belgrade near the top of the world air-quality tables on the worst January mornings.65climate
  21. 🇮🇹 Turin, ItalyPo valley smog season · 1 Oct – 31 MarThe city sits in a bowl with the Alps on three sides, and winter inversions trap particulates for days.65climate
  22. 🇷🇸 Novi Sad, SerbiaWinter air pollution · 15 Nov – 28 FebCold, still days over the Pannonian flat trap household heating smoke and the city regularly logs some of the worst readings in Europe.63climate
  23. 🇧🇦 Banja Luka, Bosnia and HerzegovinaWinter heating smog · 15 Nov – 28 Feb (usually)Solid-fuel heating plus a valley inversion parks the smoke over the city on still winter days, and January is reliably the worst of it.63climate
  24. 🇮🇹 Milan, ItalyPo valley smog season · 15 Nov – 28 Feb (usually)The valley sits under the Alps with nowhere for the air to go, so still cold weeks stack particulate up until the region bans the oldest cars.62climate
  25. 🇰🇬 Bishkek, KyrgyzstanWinter smog · 1 Nov – 1 Mar (usually)Coal stoves in the private housing around the city plus an inversion in the bowl put Bishkek near the top of the world air-quality lists on winter mornings.62climate

…and 9 more in November.

What's on around the world in November →

Winter smog in December

  1. 🇮🇳 Varanasi, IndiaPost-Diwali smog · 25 Oct – 10 Feb (usually)Stubble burning upwind, firecrackers and a cold air trap put the plains under a brown haze from Diwali onward.92climate
  2. 🇹🇼 Taichung, TaiwanAutumn and winter haze · 15 Oct – 31 Mar (usually)Once the summer winds drop, the mountains behind the city stop the air moving and central Taiwan's industry and power stations sit in it.90climate
  3. 🇧🇩 Dhaka, BangladeshDry-season air · 15 Nov – 28 FebBrick kilns fire through the dry months, the construction dust never stops, and the city trades places with Delhi and Lahore at the top of the daily air rankings.87climate
  4. 🇮🇳 Agra, IndiaWinter smog season · 1 Nov – 31 Jan (usually)Cold still air over the Doab holds in field smoke, brick kilns and traffic, and the monument can vanish from the far end of its own garden before ten.86climate
  5. 🇹🇼 Kaohsiung, TaiwanWinter air-quality season · 1 Oct – 31 Mar (usually)The rain stops, the wind drops and the petrochemical belt on the north side has nowhere to go.84climate
  6. 🇵🇰 Lahore, PakistanSmog season · 15 Oct – 31 Jan (usually)The province declares a smog season and acts on it: schools shut, offices go part-remote, brick kilns and building sites stop.83climate
  7. 🇵🇰 Islamabad, PakistanWinter haze from the plains · 1 Nov – 15 Jan (usually)The Punjab smog does not stop at the motorway.80climate
  8. 🇨🇳 Chengdu, ChinaWinter smog · 15 Nov – 28 FebThe basin holds its own air all winter under an inversion.69climate
  9. 🇨🇳 Shanghai, ChinaWinter haze · 15 Nov – 28 Feb (usually)Still, cold weeks trap particulates over the delta and the skyline goes flat grey for days until a front clears it.68climate
  10. 🇮🇷 Tehran, IranWinter inversion smog · 15 Nov – 28 Feb (usually)Cold air traps the traffic exhaust against the mountains for days at a time and the government closes schools and offices when it gets bad.68climate
  11. 🇦🇱 Tirana, AlbaniaWinter air pollution · 15 Nov – 28 FebOld diesel cars in a basin ringed by hills, plus wood heating, and the winter readings climb well past what the city's reputation for mild weather suggests.67climate
  12. 🇨🇳 Pingyao, ChinaHeating-season smog · 15 Nov – 15 Mar (usually)Shanxi is China's coal province and the central heating goes on in the middle of November.66climate
  13. 🇨🇳 Xi'an, ChinaWinter smog · 15 Nov – 28 FebThe Guanzhong basin traps its air under the Qinling mountains all winter, and Xi'an posts some of the worst readings in the country.63climate
  14. 🇧🇬 Plovdiv, BulgariaWinter smog · 1 Nov – 10 Mar (usually)Wood and coal stoves in the surrounding villages, plus an inversion that traps everything over the Thracian plain, give Plovdiv some of the worst winter particulate readings in the EU.61climate
  15. 🇮🇹 Turin, ItalyPo valley smog season · 1 Oct – 31 MarThe city sits in a bowl with the Alps on three sides, and winter inversions trap particulates for days.60climate
  16. 🇹🇷 Ankara, TurkeyWinter inversion · 15 Nov – 28 Feb (usually)The city sits in a bowl and cold, still weather traps household heating smoke in it for days at a time.60climate
  17. 🇲🇰 Skopje, North MacedoniaWinter air pollution · 1 Nov – 28 FebHousehold heating and traffic under a valley inversion make this one of the worst-affected capitals in Europe, and schools have been closed over it.59climate
  18. 🇮🇹 Milan, ItalyPo valley smog season · 15 Nov – 28 Feb (usually)The valley sits under the Alps with nowhere for the air to go, so still cold weeks stack particulate up until the region bans the oldest cars.57climate
  19. 🇷🇸 Belgrade, SerbiaWinter smog · 1 Nov – 15 Mar (usually)Household coal and wood, old cars and a windless inversion over the confluence put Belgrade near the top of the world air-quality tables on the worst January mornings.57climate
  20. 🇧🇦 Banja Luka, Bosnia and HerzegovinaWinter heating smog · 15 Nov – 28 Feb (usually)Solid-fuel heating plus a valley inversion parks the smoke over the city on still winter days, and January is reliably the worst of it.57climate
  21. 🇷🇸 Niš, SerbiaWinter heating smog · 1 Dec – 28 Feb (usually)The same basin that traps the summer heat traps coal smoke from December to February, and the readings go from ordinary to genuinely unhealthy.57climate
  22. 🇧🇬 Sofia, BulgariaWinter smog · 1 Nov – 10 Mar (usually)The city sits in a basin under Vitosha and the cold air does not move; wood and coal heating in the outer districts then fills it.55climate
  23. 🇩🇪 Stuttgart, GermanyValley inversion air · 15 Nov – 28 Feb (usually)The city centre sits in a steep bowl with almost no through wind, which is why it spent years as Germany's worst spot for traffic particulates and still traps its own air on still winter days.53climate
  24. 🇷🇸 Novi Sad, SerbiaWinter air pollution · 15 Nov – 28 FebCold, still days over the Pannonian flat trap household heating smoke and the city regularly logs some of the worst readings in Europe.53climate
  25. Pristina, KosovoWinter air pollution · 1 Nov – 28 FebTwo lignite power stations sit just outside the city and household heating adds to them, and cold still nights trap the lot in the basin.52climate

…and 10 more in December.

What's on around the world in December →