Every city has its own distinctive smell.

One of my hometown’s greatest — and most unfortunate — claims to fame is a nose hair-scorching stench that used to greet motorists traveling along Interstate 5 near the industrial tide flats. The sources of this ubiquitous rotten egg odor — a noxious combo of rendering plants, belching pulp mills and low tide along a polluted waterway — have since been remedied. But on certain days, you can still catch a faint whiff of the city’s signature stink. (My hometown, by the way, conveniently rhymes with "aroma.")

Now through June 23, the historic fjord-side city of Trondheim, Norway, is hosting the signature stinks of six major global cities — London, Beijing, Cairo, New Delhi, São Paulo and Trondheim — as part of a scent-based interactive art installation appearing at the Starmus Festival, a gathering that celebrates the intersection of science and the arts. Taking the form of six interconnected and individually perfumed geodesic domes, this temporary showcase of urban aromas is called "Pollution Pods."

While the name of the installation is a dead giveaway, it's worth noting that the city-specific smells replicated for "Pollution Pods" aren’t necessarily pleasant. Most of — but not all — of them mimic smells generated by planet-harming human activities.

Inside a pollution pod at the Starmus IV Festival in Trondheim, Norway No freshly baked baguettes or chocolate smells here: The city-specific scents presented in Pollution Points aren't all delightful .... and that's the point. (Photo: Thor Nielsen / NTNU/flickr)

"The pollution cocktail in real urban air contains ozone, nitrogen dioxide, sulphur dioxide and carbon monoxide, among other things," explains Christian Klöckner.

Klöckner is the head of Climart, a four-year research project launched at the Norwegian Institute for Science and Technology (NTNU) in Trondheim that explores the relationship between climate-themed art and consumer behavior.

But not to worry — the air wafting through each of the six domes won’t actually be loaded with harmful, foul-smelling pollutants.

"We don’t want the air in the domes to expose the public to danger, so we’ll remove the most dangerous substances and replace them with harmless ingredients and fragrances that resemble the real city air," Klöckner tells Gemini, a news journal published by NTNU. "The Norwegian Institute for Air Research (NILU) is contributing its expertise to create the right air mixtures for each dome, so that the smell and feel of breathing in the air is realistic."

Bright lights, smelly city

In bringing "Pollution Pods" to life — and to this year’s Starmus Festival — Klöckner and his colleagues at Climart collaborated with Michael Pinsky, a lauded British artist whose installations provide a visualization of climate change and other topical issues.

Among Pinsky’s best-known works are "Plunge," a 2012 installation in which a trio of iconic London monuments were encircled with brilliant blue LED rings that signify how far water levels in the middle of the British capital will rise in 1,000 years — that is, if drastic measures aren’t taken to curb human activities that contribute to a warming planet. For "L’eau Qui Dort," a piece commissioned in conjunction with the 2015 United Nations Climate Change Conference, Pinsky resurrected 40 pieces of discarded trash — bicycles, fridges, shopping carts, you name it — from a watery graves in Paris’ recently dredged Ourcq Canal. He then returned the rubbish to the canal where it was elevated above the water and bathed in an eerie blue light in so that they resembled household waste-wraiths floating above the murky depths.

While Pinsky conceived the concept and designed the six dome structures, Dutch "aroma jockey" Jorg Hempenius was enlisted by Climart to concoct the actual scents.

Michael Pinsky, pollution pods Working in an array of mediums, British artist Michael Pinsky's past works are similarly themed around environmental issues. (Photo: Thor Nielsen / NTNU/flickr)

Vibeke Ann Pettersen writes for Gemini:

The six pods on exhibit during the Starmus festival are geodesic domes, where triangles are assembled in a special pattern using wooden sticks. Plastic and metal hubs connect the wooden framework. The pods are six metres in diameter and are linked by small corridors to form a large circle. The walls inside the domes are clad with a special type of transparent plastic that will keep the air inside. At the same time, the transparency creates a visual effect, both for those inside and outside.

The space pod-y — or perhaps planet-esque — shape of the installation is meant to complement the festival and its roots in astrophysics. (This year’s theme: "Life and the Universe.")

So the big question: what exactly does Cairo — and São Paulo and London and the others — smell like?

Leading up to the Starmus Festival, Climart appeared to be holding the answer to this question somewhat close to its vest. Perhaps this was to maintain an element of surprise for festival-goers stepping into the domes and inhaling the simulated scents for the first time. However, Pinsky gave Live Science a few olfactory spoilers in a recent interview. He notes that London is "primarily diesel fumes" while the air in São Paulo, Brazil’s largest city, has a whiff of rubbing alcohol to it due to the ubiquity of ethanol fuel.

"Delhi is a cocktail of almost everything imaginable — crop burning, diesel, rubbish burning (plastic) and dust," he reveals.

A street in New Delhi, India The smell of cities like New Delhi, India, can be strange, exciting, enticing, unpleasant. 'Pollution Pods' aims to show that some of the less appealing scents are man-made. (Photo: Juan Antonio Segal/flickr)

Raising a stink in Trondheim

As for the Trondheim-scented pod, naturally Pinsky wouldn’t want to give the city hosting his installation a notably foul stench. And besides, everything in Norway is perfect to begin with.

In that particular pod, the least humid one with the cleanest-smelling air, visitors will "recognize the beautiful fragrances of fjord and forest, and perhaps you catch a whiff of summer meadow."

Hmmm. I wonder which pod is drawing the biggest crowds?

Or perhaps the festival’s native attendees, knowing that the smells won’t harm them, will want to step out outside of their olfactory comfort zones and experience the scent of a larger — and dirtier — metropolis, no matter how off-putting. It’s like traveling to a big foreign city for the very first time — the sights, sounds and smells might not all be agreeable, some even scary or distressing, but that particular city owns them and is all the more authentic because of it.

And as Pinsky explains in an artist statement, with that authenticity can come dire health impacts, particularly in developing areas.

The release of toxic gases from domestic and industrial sources both increase the rate of global warming and have a direct effect on our present-day health. In the West, in cities such as London, one in five children suffer from asthma, whilst in the developing countries such as Delhi, over half the children have stunted lung development and will never completely recover.

Within this installation we will be able to feel, taste and smell the toxic environments that are the norm for a huge swathe of the world’s population.

Klöckner, who is also a professor of psychology at NTNU in addition to leading Climart, hopes to glean a better understand of how the general public will react to a work of climate art, particularly one that comes equipped with a half-dozen smells that are likely both to be found as both offensive and familiar.

Will they stick around? Or will they head straight to the exit? And how will encountering a smell associated with air pollution prompt them to take action?

"Some emotions are more likely to inspire us to do something, Klöckner tells Gemini.

An artistic rendering of Pollution Pods If you had a dome filled with the scents of your city or neighborhood what would it smell like? (It's burnt coffee, truck fumes, garlic and the unholy stench of a nearby fish processing plant for me.) (Rendering: Climart)

After the conclusion of Starmus, Klöckner hopes to bring the installation to cities beyond Trondheim. No word if the six featured city smells would be swapped out for new ones.

Now in its fourth edition, the Starmus Festival, a sort of weird cosmic convergence of rock stars and rocket scientists founded by Armenian astrophysicist Garik Israelian with support from fellow astrophysicist (and Queen guitarist) Brian May, features an enviable roster of speakers including Stephen Hawking, Brian E. Cox and Neil deGrasse Tyson. And given the festival’s emphasis on astronomy and space exploration, no less than 10 astronauts — Buzz Aldrin, Sandra Magnus and Charlie Duke among them — will be on hand during the gathering.

Alongside Pinsky, several other artists and musicians have also installed works or are slated to perform. (With legendary guitarist Steve Vai appearing onstage alongside Nuno Bettencourt of Extreme, it's obvious that this is an event with Brian May sitting on the board of directors.)

This is the first time the Starmus Festival has been held in Trondheim. Previous editions (2011, 2014, 2016) were all held on Tenerife, the largest of Spain’s Canary Islands and a place that probably smells like salt water, pine and oleander with a slight whiff of rotten eggs no thanks to the presence of a large oil refinery.

What does your city or town smell like? Perhaps it's time you explore the urban smellscape to find out.

Matt Hickman ( @mattyhick ) writes about design, architecture and the intersection between the natural world and the built environment.