Calne landfill stink investigation in Wiltshire concludes

The findings of a report by the UK Health Security Agency follow thousands of reports to the Environmental Agency about the so-called Calne Stink.

The odour was found to be emanating from Lower Compton Landfill in Calne, operated by Hills Waste Solutions.

The UKHSA evaluated 184 days of Environmental Agency monitoring data collected between October 15, 2025, and April 16, 2026, following an increase in odour complaints from the community.

A UKHSA spokesman said: "Overall, the monitoring results for hydrogen sulphide, particulate matter and methane do not indicate an exceedance of the relevant standards or health-based guidance values.

"Based on the currently available monitoring data, there would be minimal risks to public health at these levels of exposure from a toxicological perspective."

Hydrogen sulphide is the gas that produces the "eggy" smell residents have been complaining about.

Temporary symptoms can include headache, nausea, watery eyes, and irritation of the throat and nose.

People with underlying respiratory conditions, such as asthma or COPD, may be more susceptible to these effects.

Hydrogen sulphide levels exceeded the World Health Organization’s odour annoyance guideline during 1.3 per cent of the monitoring period, but this fell below international acute health risk thresholds.

Although the report found no immediate toxicological risk, it warned that regular exposure above the odour threshold could lead to persistent short-term symptoms.

Lucy McCann, consultant in health protection at UKHSA South West, said: "While there is no evidence of a toxicological risk, there is strong evidence of odour annoyance.

“Individuals can react differently to hydrogen sulphide odour, and some people may be more sensitive to it than others.

"People living near the site may experience temporary symptoms including headaches, nausea, dizziness, watery eyes, a stuffy nose, an irritated throat and coughing.

"Those with pre-existing respiratory conditions may be particularly affected, and some residents may also experience sleep disruption and stress.

“If you have concerns about your individual circumstances and require health advice, please contact your GP."

The findings of the report will be explored at 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 Environment Agency, UKHSA, Wiltshire Council and Hills. 

Ben Shayler, area environment manager from the Environment Agency, 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.”

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A spokesperson for Hills said: "We welcome the report from the 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."

The Environment Agency said it would "continue to regulate the site closely and will take further enforcement action where necessary to ensure permit compliance and minimise environmental impacts."