Milpitas, an affluent city in California’s Silicon Valley tech hub, has an odour problem. For decades, residents have had to endure rank smells wafting from industrial sites, among them a 342-acre landfill. “When I first moved here, I could not open my window for over 10 years,” says Chia-Ling Kong, an engineer for a tech firm who lives around half a mile from the dump. While things have got better in recent years, Kong says she and her neighbours must still contend with around “two or three hours of bad smells a day”.
Perhaps befitting Silicon Valley, the community is putting its hopes in technology. The operators of Newby Island landfill have been ordered by local authorities to use drones and install monitors to systematically track and measure the chemicals responsible for bad odours. They have also been told to automate the collection of landfill gases responsible for smells. Kong is optimistic a data-driven approach will make a difference.
“Hopefully with this continuous monitoring, it makes it easier to pinpoint problems at the moment it starts.” The operators of the landfill say they are committed to operating it safely and protecting air quality. Just like in Milpitas, where Kong is part of a citizen’s campaign against the odours, communities around the world are raising a stink about bad smells making day-to-day life miserable. Sometimes a rubbish dump is to blame, or it might be a sewage treatment works, or a reeking factory. When the complaints start stacking up, resolving them is not always simple.
Many countries have no regulations in place dictating how to manage smells. In the US, for example, the Environmental Protection Agency does not regulate environmental odours as a pollutant. This leaves states and local governments to take charge of the issue. Urban sprawl is often part of the problem, bringing communities closer to stinky facilities that may historically have been kept at a distance.
This is creating more demand for technologies to monitor and prevent smells. Odour consultant Micheal Bull says people are increasingly concerned about neighbourhood stinks. “You’re getting developments being built nearer to odorous processes… as land has become more valuable, there is also infilling,” Bull says. He is speaking about his experiences in the UK, but it’s a similar story in many parts of the world.
The technologies used to tackle industrial pongs generally fall into three categories: they absorb odours; convert them into something less smelly through a chemical reaction; or burn them away. Experts on fixing industrial odours say that the best technologies, when used correctly, can remove 90% or more of the target compounds responsible for smells. But this can be expensive and some operators opt for simpler and cheaper solutions. These include masking odours from landfill or sewage processing by spraying giant quantities of deodorisers.
Odour experts contacted for this article were dubious about the effectiveness of such industrial scale air fresheners. “In my view they’re not likely to change the odours,” says Bull, who likens them to fabric conditioner. Bad smells from waste sites – a common cause of complaints – are among the stinkiest and most difficult to resolve, according to Carlos Diaz, an environmental consultant based in Spain. “Landfill is difficult to treat because you have a very large surface,” he says.
In some places at least, technology is making a real difference. Residents in Des Moines, Iowa, have long complained of the so-called Eastside Funk, a putrid scent that residents report drifts over parts of the city. A study commissioned by city authorities showed that a trio of industrial meat companies were among culprits. “Within 10 miles, there’s about half a million people,” says Dalton Jacobus, who works in the Department of Neighborhood Services.
“If the winds are out of the wrong direction, 100,000 people can be in the middle of that odour plume.” The authorities are now paying around $240,000 (£182,000) a year on technology to track the stink, so they can take action. “What we wanted to do was build a ring of odour monitors around the facilities that we suspected of emitting odours,” says Jacobus. The monitors, which measure levels of chemical compounds in the air, work in combination with a weather station to provide real-time data on the concentrations that are coming from each facility based off the wind patterns. This has put an end to finger pointing about who’s to blame each time a smell sparks complaints, says Jacobus.
“Now we can say with reasonable certainty that ‘this odour event did originate from your facility, what was going on’?” Meanwhile, some of the sites that have been blamed for causing unpleasant smells in Des Moines have spent millions of dollars to upgrade their own odour control systems. Smithfield Foods, which operates a meat processing in Des Moines, says it has invested $2m to install a regenerative thermal oxidiser that destroys the chemicals associated with bad smells. Even so, the company says it does not believe it is the source of odour complaints. Before installing the monitors – which some local companies help pay for – officials in Des Moines would drive out to the source of a complaint to sniff the air.
Relying on the human nose to sniff out industrial smells is still commonplace. Claudia Barrios Obregón from Kunak, the company behind the monitors in Des Moines, says: “Right now, the way that cities control or measure odours is olfactometry: a human panel measures and gives an opinion of what the odour is like. But that’s not that realistic.” The Spanish company’s monitors are an example of so-called electronic noses that make it easier to detect smells. Whatever technology is used, it can be hard to keep everyone happy, as smells are so subjective.
“Unfortunately, the general rule is that the nastier we perceive the odour to be, the more sensitive towards it we are,” says Johan Lundström, a professor in the science of smell at the Karolinska Institute in Stockholm, Sweden. The extreme engineering of aircraft windows Should promotion depend on how workers use AI? Will self-flying planes transform the skies?
