Catching a whiff of sewage, exhaust or vape smoke in a city street usually isn’t anything to write home about. But if a smell in the Lower Mainland makes you wrinkle your nose, a UBC research study called SmellVancouver wants to know.
SmellVancouver, or SmellVan, is a citizen science experiment which collects anonymous tips about smells via a web-based app. To file a tip, you can rate smells on a scale of mildly to extremely offensive, describe the scent and mention any steps you took to deal with it — such as closing the windows or using an air freshener.
While each odour complaint is personal, smell trends can also be political. SmellVan is partnered with the regional government, and it hopes that its research can help Metro Vancouver create air quality legislation that represents the publics’ priorities.
The project reveals that odour may tie into bigger issues including air pollution, environmental injustice and a municipal debate about the health implications of cannabis traces in public spaces.
Following the scent of environmental injustice
Smell can majorly impact people’s psychological state and mood. SmellVan’s dataset reveals not only odour descriptions, but also emotional cries for help.
“People really express themselves,” said SmellVan researcher and UBC mechanical engineering postdoctoral fellow Sahil Bhanderi. “If they’re upset, they say things like, ‘I don’t even know what to do anymore. I just want to flee, I just want to hide.’”
Industry does not distribute odour pollution equally. The SmellVan team sees its research on smell not only as an atmospheric science study, but as an environmental justice issue.
“Work done over the past two decades has shown that environmental injustice is very prevalent — it’s everywhere,” said Bhanderi. “People who are living near polluting sources are more likely to be of a minority community — it’s a fact.”
Vancouver is no exception. In a 2020 study, UBC environmental scientists Dr. Amanda Giang, associate professor at the Institute for Resources, Environment and Sustainability (IRES), and Kaitlin Castellani, research assistant at the IRES, found that the Downtown Eastside’s Indigenous population faces elevated levels of air pollution, as do the majority-racialized South Vancouver suburbs.
“Even though we’ve made tremendous progress in reducing air pollution … those gaps are still there across communities,” said Bhanderi. “We are identifying specific census tracts where there are pollution hotspots … so we are doing this targeted analysis of communities that are worst hurt or the most affected.”
Tracking smells to their sources
Once SmellVan finds these hotspots, its main goal is to identify the odours’ causes.
In comics, tracking the source of a smell is as easy as floating along the scent lines to a pie on the windowsill. For scientific purposes, it’s more complicated. How can you systematically and analytically distinguish one smell from another?
“As soon as [a chemical gets] emitted in air, it starts reacting with other things: traffic emissions would react with emissions from trees, which would react with emissions from factories, and also emissions from restaurants and every other source,” said Bhanderi.
One way to accurately track a scent is to follow the wind. The SmellVan team utilized a technique to systematically analyse wind patterns called dispersion modelling, where wind parcels are tracked to determine where a smelly breeze may have originated.
The team also uses what UBC atmospheric sciences PhD student in the department of earth, ocean and atmospheric sciences Davi de Ferreyro Monticelli calls the “Plume Van” — a mobile unit with air quality monitors to test for pollutants such as carbon monoxide and nitrogen oxide.
“Eventually we would like to … take the reports from SmellVancouver, see the regions where people are complaining the most, take the Plume Van to those places and try to have an analysis of the air quality situation there,” he said. “[Then] we can analyse environmental variables, such as temperature and wind direction, and see how they contribute to the particular odour event.”
To get to the source though, SmellVan needs as much information as possible about what people are smelling and where.
Crowdsourcing policy with citizen science
SmellVan uses a method called citizen science, in which data for analysis is shared by the public.
“What we’re trying to do is use this odour experience of people, which is our citizen science source, to link to chemicals which are quantifiable and which policymakers and policy researchers can measure and then control,” said Bhanderi.
Regulations might look like setting maximum allowable levels of chemical concentrations in the air, noted Bhanderi. For policy to serve the public, it helps to get data on what smells ordinary people perceive as problematic.
“Odour complaints are the biggest source by which the public gives feedback [on air pollution] to policymakers,” said Bhandari.
“If you think about it, it makes sense, right? I can’t see those small particles in the air, I can’t track it, but I can smell stuff. And if it’s making me uncomfortable, well, I need to voice it.”
‘Stinky’ is subjective
How people perceive the same smell might vary widely based on preference, brain chemistry and personal history.
That’s why SmellVan provides the option to report smells on a spectrum, from neutral to negative. Whether you think a noticeable odour smells nasty or normal, if you detect it, the Vancouver Smell Map team wants to know about it.
Another common yet controversial smell in Vancouver? Weed.
“Cannabis is actually one of our priority industries for the SmellVan analysis,” said Bhanderi. “That’s a source [of odour pollution] that Metro Vancouver is concerned about.”
While many enjoy or are indifferent to the smell of cannabis, others find it nauseating. Since Canada legalised recreational cannabis in 2018, farms and dispensaries have been increasing throughout the country and so have smell complaints in Vancouver.
In 2019, an air quality planner proposed recommendations for Metro Vancouver to regulate odour pollution from the cannabis industry on the grounds of environmental and public health impacts.
Industrial cannabis agriculture produces Volatile Organic Compounds (VOCs). When exposed to sunlight and combined with nitrogen oxides in the air, it creates ground-level ozone, or smog — a harmful air contaminant, especially for asthmatics and those with other preexisting conditions.
However, some cannabis industry professionals argue that Metro Vancouver is targeting them unfairly. Many other industries produce VOCs as part of their regular operations, including organic manure farming and their odours are not regulated by the provincial government, though Metro Vancouver does issue “discharge limits in some industrial permits.” However, the specific industries being impacted are not specified.
For SmellVan, the priority is the science. Its goal is to collect a meaningful sample of public perception about who is smelling what and where, and let the data speak to policymakers for itself.
‘Limitations of citizen science’
However, Bhanderi said that the respondents so far skew older, whiter and wealthier than the general population of Vancouver. This represents “one of the limitations of citizen science,” they said.
Without a representative sample to inform policy-making on air pollution (including cannabis smoke), privileged noses may shape legislation — echoing existing socioeconomic biases in Canadian voting trends.
SmellVan hopes to get more engagement from youth and low-income populations. Bhanderi mentioned that SmellVan’s Instagram and Twitter (@smellvancouver) post regularly to try and reach broader audiences.
“We need more young people to report odours,” said Bhanderi. “If you ever experience any odours, whether they be pleasant, or not so pleasant, feel free to report to us.”
Despite its limitations, SmellVan sees citizen science as a powerful tool to build civic engagement and public trust in science — a trust which has been dangerously eroding in recent years.
“With great communication between scientists, the regulators and the public, eventually, everyone grows into a more engaged community,” said de Ferreyro Monticelli. “[When the public] sees the science working for them on their behalf, it’s something very, very positive.”
A previous version of this story misstated that Smell Vancouver is partnered with the City of Vancouver when it is in fact partnered with Metro Vancouver, the regional government. A previous version of this story also represented ground-level ozone as a carcinogen, when it can be more accurately described as a harmful contaminant. This article was updated on May 21, 2022 at 9:30 a.m. to reflect this change.