The Environment Agency (EA) began monitoring the Hills Waste landfill site near Calne last year after thousands of residents reported a “disgusting smell” causing headaches, nausea and dizziness. In the last two months alone, more than 1,600 complaints have been made about the odour, locally known as the ‘Calne pong’ or ‘Calne stink’.
Between October 2025 and April 2026, the EA checked for levels of hydrogen sulphide, methane and particulates at the site in Lower Compton and in nearby residential areas. On Thursday, the UK Health Security Agency (UKHSA) released a report finding “minimal risk” to human health in the longer term, but revealed repeated instances where odour levels exceeded World Health Organisation (WHO) guidelines.
Odour levels and health impacts
According to WHO, an odour becomes an ‘annoyance’ at levels of 7 µg/m³ (0.005 parts per million) over a 30-minute averaging period. People exposed to hydrogen sulphide above this level can experience temporary symptoms including headaches, nausea, dizziness, watery eyes, stuffy nose, irritated throat, cough, sleep problems and stress, particularly those with pre-existing respiratory conditions like asthma. Symptoms typically disappear once levels drop.
The UKHSA report found that over six months, acceptable levels of hydrogen sulphide were exceeded on 106 occasions. The highest 30-minute average concentration was 69.3 µg/m³ – roughly 10 times higher than WHO recommends.
UKHSA recommendations
The UKHSA is recommending that “all appropriate measures” be taken to reduce off-site odours from the landfill and reduce impact on the local community. It is also advising Calne residents to contact their GP regarding individual health concerns, which will help the NHS better understand the landfill’s health impact.
“While there is no evidence of a toxicological risk, there is strong evidence of odour annoyance,” said Lucy McCann, consultant in health protection at UKHSA South West. “If you have concerns about your individual circumstances and require health advice, please contact your GP.”
Hills Waste response and remediation work
Hills Waste is cooperating fully with the EA and is working to change how waste at the site is covered, including capping off sections that are causing problems. The work is expected to be completed in July, after which odour issues should decline. The EA will continue to “regulate the site closely” and take further enforcement action where necessary to ensure permit compliance and minimise environmental impacts.
A spokesperson for Hills Waste said: “Hills welcomes the report from UKHSA regarding the monitoring of air quality in Calne and any effects on human health. Hills has been working with the Environment Agency consistently during that time. Since May, Hills has accelerated the rate at which completed areas of landfill have been clay capped. Hills is also increasing the number of gas wells at the landfill with captured emissions being used for the generation of electricity.”
Resident experiences
Leigh Randell, who lives in Calne with his wife and daughter, said: “I have been to the doctor three times, so I have medicine to take now for the headaches. We are fed up. The stink yesterday afternoon smelt like decomposing rubbish. My wife and little girl have asthma and they are heavily affected. It affects their breathing. It's just unbearable.”
Community drop-in event
The EA is planning to host a community drop-in event at Calne Town Hall on Tuesday, July 21, from 4pm to 7pm. The event will be attended by representatives from the EA, UKHSA, Wiltshire Council and Hills.
Ben Shayler, area environment manager at the EA, said: “This drop-in event will give residents the opportunity to understand the work we are doing to regulate Hills, and ask questions of the agencies involved. We have taken extensive action to require Hills to address the source of the odour, and these works are now nearing completion. We will continue to regulate the site closely and monitor to ensure the works have been effective.”
