Still, the merest whiff of stench may be intolerable for some people, but for others, it can be barely noticeable. “There will be a wide range of responses; some will say they smell it occasionally, or it just doesn’t bother them,” says Dalton, who regularly investigates odour complaints. Age, gender, allergies and lifestyle choices like smoking are all among the factors how people perceive odours.
You may hope that people could just get used to an unpleasant smell over time, but repeated exposure to unpleasant odours, such as those from landfill, doesn’t necessarily make them easier to tolerate.
In contrast, it is normal to habituate to neutral or pleasant smells. “Once you have smelt an odour, and identified that it’s not going to kill you, then you stop being able to smell it,” says Lundström. This is also why people, despite the human nose being able to detect one trillion odours, generally find it more difficult to name smells from things that aren’t dangerous. Sniff tests suggest that less than half of us may be able to correctly name everyday odours like coffee or vanilla, for instance.
Fighting a stink
A stench can sometimes come and go – often with the prevailing wind – or may be noticeable only in some parts of any given neighbourhood. “It can be hyperlocal,” says Amanda Giang, associate professor of environmental modelling and policy at the University of British Columbia, in Canada, who has investigated the impacts of odour pollution on residents in Vancouver. “I could live a block away and never know that the block over it smells like rotting fish.”
But not all stenches are experienced equally: disadvantaged neighbourhoods, with cheaper housing, are often closer to stinky landfill sites or heavy industry. Studies conducted in Europe and the UK suggest that in some countries, people from low-income communities are more likely to live within a 1.25 mile (2km) radius of waste incinerators, landfills and hazardous waste sites than those with higher incomes.
Complaints about horrible smells can provoke change: sites ranging from sewage plants to fish processing factories have been forced to scale down or stop their operations, following campaigning from residents. There are also growing, but uneven efforts in countries around the globe to better control odour pollution, from a new regulation on odours from fish feed plants in Chile, to tougher rules on how much stink companies are allowed to make in residential areas in Lithuania.
Odorous benefits
For those living in a neighbourhood plagued by unpleasant odours, life can be difficult, but there is at least one small consolation: having a well-functioning sense of smell is an important part of good health.
Research has shown that people with a keener sense of smell take greater enjoyment from eating, and even sex: in a 2018 study of 70 adults, those with high olfactory sensitivity reported greater pleasure from sexual activities and, among those, women also reported a higher frequency of orgasms during sexual intercourse.
