Many cities worldwide struggle with air pollution, caused by everything from endless cars to power-guzzling factories. And sadly, in many urban hubs across the globe, air pollution is on the rise – in fact, the World Health Organisation (WHO) says that, as of 2022, 99% of the world’s population was breathing polluted air. In response, HouseFresh has analysed data to determine the places where the PM2.5 level (the amount of fine particles in the air) has increased the most in recent years. Findings are measured in PM2.5 micrograms per cubic metre of air (µg/m3). 

Click through the gallery to discover some of the most polluted cities in the world...

Pokhara is ripe with natural wonders, serving as a gateway to the Annapurna Circuit trail, which beats a path through the Himalayas, and Phewa Lake, which the city borders. However, these natural sights might well be viewed through a haze as air pollution worsens. The city recorded a rise of 23.6 µg/m3, likely a combination of polluting industrial factories and open waste burning.

Coming in behind Pokhara is Arak in Iran. This little-touristed city is better known for its industrial might, serving as the country's prime industrial capital. It remains the largest aluminium manufacturer on the planet, and it's also home to a vast sodium sulphate mine, as well as giant oil and gas refineries (as pictured). No wonder, then, that the city's air pollution was listed as +25.8 µg/m3.

Another industrial heavyweight, Iran's Karaj is a stone's throw west of buzzing capital Tehran, knitted into the foothills of the Elburz Mountains. While it attracts few tourists, the city manufactures a huge range of products in its giant factories, from paper and textiles to cars and steel. But this manufacturing prowess comes at a cost: the air pollution levels were recorded as +26 µg/m3 in the study.

The Iranian capital has plenty of jewels – from the sumptuous Golestan Palace complex, dating back to the 16th century, to the treasure-rich National Museum of Iran, plus views over to the Alborz mountain range. But the city's air pollution levels have increased significantly in recent years (+26.5 µg/m3). Reports put this down to factors including rapid population growth and rising fuel consumption. (Note that the FCO currently advises against all travel to Iran).

No, not that East London... South Africa's East London noses up to the Indian Ocean, and includes attractions such as the stately City Hall, an impressive Victorian-style building that's washed in pinkish red. However, the city's rising air pollution levels were reported as +28.8 µg/m3, mostly likely due to its titanic motor industry.

Baghdad, the most populous city in Iraq, situated on the Tigris River, records air pollution levels of +31.6 µg/m3. Reports attribute the increasing levels to a number of factors, including military conflicts and large-scale manufacturing. Note that the FCO advises against all travel to most provinces of Iraq.

Pakistan's largest and capital city is awash with wonders, from the striking Badshahi mosque (pictured) to the Lahore Fort, an intricate citadel that dates from the 16th-century Mughal Empire. But, sadly, the city's air pollution is on the rise (+33.5 µg/m3). The mushrooming smog has been known to disrupt flights and close roads and is mostly the result of large-scale fossil-fuel use, including the burning of coal in brick kilns. Check FCO advice before travelling to some areas of Pakistan.

Colourful Oaxaca is lauded for its larger-than-life Day of the Dead celebrations and its eye-catching architecture, including soaring Catholic cathedral Templo de Santo Domingo de Guzman. But sadly, it's becoming increasingly known for its air pollution too. The data shows a rise of +37.6 µg/m, which is attributed to factors including the burning of waste.

Known for ultra-modern architecture, luxurious lifestyle and a lively nightlife, Dubai might be loved by tourists but it is also the most populated city within the United Arab Emirates. As cars remain the number one mode of transport in the Middle Eastern city, air pollution is constantly on the rise. However, though pollution levels have recently risen by +50.2 µg/m, Dubai aims to produce a third of its energy from clean sources by 2050.

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Tourism in Saudi Arabia is booming, with travel to the country predicted to grow explosively over the coming decades. But, unfortunately, like many cities in the Middle East, Dammam, capital of Saudi's Eastern province, faces issues with air pollution – in fact, its pollution levels have grown more than any global city (+111.1 µg/m). HouseFresh recognises the city as an oil industry hub and says it's home to the Persian Gulf's biggest port and the world's largest airport.

Hailed for its Revolutionary history and its fascinating museums, Virginia's capital is one of the USA's oldest cities. But it's also, sadly, one of its fastest polluting (+0.7 µg/m). This is likely due to emissions from vehicles, with reports also citing wildfires (such as those recently occurring in Canada) as being among the polluters.

Unfolding from the fringes of Saguaro National Park (home to America's largest cacti) – and tucked in amidst the Santa Catalina, Rincon and Santa Rita mountain ranges – it's hard to imagine that Tucson has any real problem with air pollution. But HouseFresh listed the city among the top 10 when it came to rising air pollution (+0.7 µg/m). Some reports attribute this to rising temperatures caused by climate change, which also increases wildfires.

Another of the USA's capital cities makes HouseFresh's list. Visitors to Indy, as it's affectionately known, can explore attractions such as the Children's Museum of Indianapolis (the world's largest) or the dazzling Newfields art museum – but they can also apparently breathe in some of the USA's fastest polluting air (+0.8 µg/m). Sources link the rising pollution to traffic and local power plants.

Knitted into the San Joaquin Valley, Fresno is best known as a jumping off point for adventures in the Sierra National Forest, as well as adventures in the Sierra Nevada mountain range. But while the outdoors might be a drawcard, the rising air pollution (+0.9 µg/m) is not. Wildfires; emissions and chemicals emitted from local farming and industrial operations; and traffic are all cited as reasons for these numbers.

California capital Sacramento is often overlooked, but there are plenty of reasons to visit – from the 19th-century neoclassical Capitol Building (pictured) to the historic Crocker Art Museum. But while the city's attractions glitter, its rising air pollution (+1.2 µg/m) might be cause for concern. Sources pin the poor air quality to heavy traffic, construction and agriculture.

It's well worth putting the Texan capital on your bucket list to experience its revered live music scene, its mouthwatering barbecue and its access to outdoor attractions such as Barton Creek. Unfortunately, you won't be able to avoid the city's climbing air pollution levels (+1.2 µg/m). The situation worsens in the notoriously hot summers, which exacerbates pollutants from sources including fossil fuels and traffic.

Drawing in tourists with its state-of-the-art Space Center and excellent Museum of Natural Science, Houston should definitely be on your list of US cities to visit. However, HouseFresh's findings do not bode well for the buzzing city. It's placed within the top five US cities for fast-growing air pollution (+1.2 µg/m). Contributing factors include emissions from cars and industrial trucks, plus those from chemical manufacturing plants and giant refineries.

Los Angeles' reputation for glitzy celebrity hangouts, stellar movie history and cult restaurants precedes it – and so too does its reputation for smog. HouseFresh named the City of Angels within the top three urban areas when it comes to increasing air pollution (+1/5 µg/m) – mostly due to its notorious traffic. It also has two of the USA's largest and busiest container ports.

When it comes to rising air pollution in the USA's cities, Utah's capital ranks second (+1.8 µg/m)). HouseFresh acknowledges that there are natural features at play here: given the fact that the city is carved into a valley, it experiences a meteorological phenomena known as 'inversion', in which cool air becomes trapped beneath warmer air, pushing pollution towards the ground. However, this shouldn't put you off Salt Lake City's epic Olympic Park or exploring the fascinating Temple Square, belonging to the Church of Jesus Christ of Latter-day Saints.

A jewel of southern Florida, thrumming Miami lures visitors with its sugar-white beaches, famous Art Deco architecture and Cuban heritage, which lends itself to a delicious food scene. But, unfortunately, the Floridian bolthole ranks number one among the USA's fastest polluting cities (+1.8 µg/m). Reports highlight increasing traffic and fierce Saharan dust storms.

You might not have heard of the central Hungarian city of Kecskemet, but it might be one to put on your watch list: savvy travellers are attracted to its attractive art nouveau architecture and meadow-stitched Kiskunsag National Park, which is right on the doorstep. However, it makes the list of Europe's top 10 fastest polluting cities (+1.8 µg/m). That's likely due to factories and power plants, as well as vehicular emissions.

The dinky northeastern city of Nancy is a feast for the eyes – replete with grand squares and a slew of art nouveau and baroque architectural landmarks. But it's number nine on HouseFresh's list of European cities with rising air pollution (+1.9 µg/m). That's likely due to traffic, though low-emission zones were introduced in 2021 in an attempt to curb the problem.

Gyor is well off the tourist trail, but those who do venture to this Hungarian city will be greeted with sights such as the Basilica of Gyor, a sumptuous Catholic cathedral; and Apatur-Haz, a 19th-century seminary. Unfortunately though, air pollution is apparently rising (+2.0 µg/m). That's most likely due to the fact that the city is the location for a large engine manufacturing plant, which supplies major motor companies including Skoda.

You may be familiar with Eindhoven since it's the birthplace of the major electronics company Philips – and though this particular industrial giant is carbon neutral in its operations, the city as a whole is ranked among Europe's fastest polluting urban areas (+2.3 µg/m). Still, the greatest minds in the city are working on solutions: experts at the Eindhoven University of Technology have invented a state-of-the-art air-purifying or 'smog eating' pavement. Watch this space...

Often compared to Venice, Dordrecht is a charming, water-laced city in the southwest of the Netherlands. Gothic churches, leisurely boat rides and treasure-filled antiques shops all await here, but so too does increasing air pollution (+2.5 µg/m), according to HouseFresh. Reports attribute pollution in the region to emissions from an industrial plant.

Poznan, in western Poland, is rising on traveller's wish lists, ever more popular for its charming Old Market Square and open spaces such as Citadel Park, home to a 19th-century hilltop fortress. But, less fortunately, air pollution is rising too (+2.6 µg/m). Most reports blame the wide use of coal as a fossil fuel.

Pristina is the capital and economic heart of Kosovo, home to striking architectural landmarks such as the National Library of Kosovo (pictured), with its bubble-like appearance created by abundant domes. Unfortunately, it comes in fourth as Europe's fastest polluting city (+2.7 µg/m). That's mainly due to a pair of coal-fired power plants, which spurn regular protests from residents of the city. Initiatives such as a new electric taxi fleet in the city are attempting to begin to combat the problem. 

Hear the word 'Dijon' and most people think 'mustard' – but there's far more to this eastern French city besides the yellow condiment. For starters, there's the dazzling Museum of Fine Arts and the sprawling Palace of the Dukes and Estates of Burgundy, which is also filled with artwork and antiquities. But regrettably, HouseFresh reports that air pollution is on the up (+3.0 µg/m) – though a series of low-emissions zones look poised to ease the problem.

Imagine Spain and you might come up with images of golden beaches, boat-fresh seafood restaurants and glittering art nouveau architecture. You'll get all that and more in Palma, on the Balearic island of Mallorca – the city also sadly suffers with increasing air pollution (+3.7 µg/m). Some reports say that this issue is due to Palma's busy cruise port, while HouseFresh cites vehicles as the main culprit.

Head to northwestern Spain and you'll discover Salamanca's incredible Old City – a rich, UNESCO-protected tapestry of baroque, renaissance and gothic buildings. However, the city ranks number one when it comes to fast polluting cities in Europe. HouseFresh puts this down to vehicular traffic, though it recognises that new low-emissions zones introduced from 2023 might help to combat the problem. 

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