Why This Matters: Persistent smells from landfills, sewage works and factories can disrupt daily life, while identifying their source is often difficult. New monitoring systems are being used to connect odour complaints with specific chemical emissions and facilities.
Technology is being used to trace the source
In Milpitas, California, residents have complained for decades about smells from industrial sites, including the 342-acre Newby Island landfill. Chia-Ling Kong, an engineer who lives about half a mile from the landfill, says conditions have improved but she and her neighbours still experience around two or three hours of bad smells a day.
Local authorities have ordered the landfill operators to use drones and install monitors to track and measure the chemicals responsible for odours. They have also been told to automate the collection of landfill gases associated with smells.
The aim is to detect problems as they begin and make it easier to identify their source. The landfill operators say they are committed to operating safely and protecting air quality.
How the monitoring works
In Des Moines, Iowa, authorities have installed what are described as “electronic noses” around facilities suspected of producing odours. The monitors measure chemical compounds in the air and work with a weather station.
Weather information helps show how concentrations may be moving from each facility according to wind patterns. Dalton Jacobus of the city’s Department of Neighborhood Services says the system has helped officials move beyond uncertainty about which facility is responsible for an odour event.
The city is paying about $240,000 a year for technology to track the smells. Officials previously drove to complaint locations and relied on people to sniff the air.
Three broad approaches to odour control
Technology used to tackle industrial odours generally falls into three groups:
- Absorption: capturing odour compounds.
- Chemical conversion: changing compounds through a chemical reaction into substances that smell less.
- Thermal treatment: burning the compounds away.
Experts cited in the report say the most effective technologies can remove 90% or more of target compounds when used correctly. However, these systems can be expensive, and some operators choose cheaper approaches such as spraying large quantities of deodoriser to mask smells.
Odour specialists questioned whether industrial-scale air fresheners are likely to change the underlying odours. Landfills can be particularly difficult to treat because they have very large exposed surfaces, according to environmental consultant Carlos Diaz.
A clearer picture in Des Moines
Residents in Des Moines have long reported a smell known locally as the “Eastside Funk”. A study commissioned by city authorities found that three industrial meat companies were among the suspected contributors.
Some facilities identified in complaints have since spent millions of dollars upgrading their odour-control systems. Smithfield Foods says it invested $2 million in a regenerative thermal oxidiser designed to destroy chemicals associated with bad smells. The company also says it does not believe it is the source of the complaints.
The monitoring systems do not remove the need for judgement. Smells are subjective, and human panels are still commonly used to assess odours. Johan Lundström, a professor of smell science at Sweden’s Karolinska Institute, says people may become more sensitive to an odour they perceive as particularly unpleasant.
Why the problem is growing
Communities around the world are reporting problems near waste sites, sewage-treatment works and factories. Urban expansion can bring new housing closer to facilities that were historically separated from residential areas.
Regulation also varies. The report says many countries have no rules specifying how odours should be managed. In the United States, the Environmental Protection Agency does not regulate environmental odours as a pollutant, leaving states and local governments to address the issue.
Limits of the technology
- Effective odour-control systems can be costly.
- Landfills are difficult to treat because of their large surface areas.
- Masking an odour may not remove the compounds causing it.
- Odour perception varies between people, making complaints difficult to assess consistently.
- Monitoring can help identify a likely source, but it does not by itself resolve the underlying emissions problem.
Bottom Line
Drones, chemical monitors and weather data are giving communities better tools to trace industrial smells. The technology may make responsibility easier to establish and help operators respond faster, but controlling odours remains expensive, technically difficult and partly subjective.
Source
This report is based on information published by BBC Science & Environment.
