Thousands of people have complained about the sulphur-like odour in Calne
A persistent “rotting egg” odour in a Wiltshire town is being monitored using “sniff testing”, the Environment Agency has said. Calne has been plagued by a “stink” from gas escaping from the Hills Waste landfill site at Lower Compton for a year, with local residents reporting breathing difficulties and headaches.
Complaints about the smell have soared in the last week, according to the Environment Agency (EA), which said more than 100 reports were made last weekend.
Last year, the EA confirmed the Lower Compton site was likely to be responsible for the smell and served Hills with an enforcement notice ordering a programme of landfill capping to reduce smells escaping from the site.
It is understood Hills is co-operating fully with the EA and is currently working to change how waste at the site is covered up.
“We recognise the ongoing impact that odour is having on residents, and we are continuing to prioritise work to address these concerns as quickly as possible,” a statement from the EA said.
“We have been out on site again to ensure Hills are delivering the actions that we have required of them to bring the site back into compliance with its environmental permit. This includes the accelerated permanent capping works.”
The main way the EA is assessing whether Hills is complying is through “sniff testing”, using officers to detect and assess odours with their nose.
“This is required by permit conditions and remains the most effective method, as the human nose can detect the full range of gases responsible for odour at very low levels,” the EA said.
“It is important to be clear that this type of monitoring is for regulatory compliance purposes and not to directly assess health impacts.”
The EA is also understood to be using a mobile monitoring facility to measure air quality, including to detect methane, hydrogen sulphide – a toxic gas – and particulates.
It is also providing its data to the UK Health Security Agency (UKHSA), which is carrying out its own independent analysis.
“We understand that residents have concerns about potential health effects, and we take these concerns seriously,” the EA added.
“We use sniff testing to assess odour impact and compliance with permit conditions, and we use monitoring data to support this and to inform UKHSA’s independent health assessment.
“Our aim is to ensure that odour is reduced to a level where it is no longer causing unacceptable impact beyond the site boundary.”
A spokesperson for Hills said: “Soil-capping works are ahead of schedule and in line with our landfill action plan as agreed with the Environment Agency.”
‘Health risk likely to be low’
UKHSA is the independent public health body responsible for assessing any potential impacts on human health. They review the monitoring data and determine whether there is any risk to the community.
In May, the UKHSA told Business Live that with the levels of hydrogen sulphide currently detected around the site, the health risk was “likely to be low”.
Lucy McCann, consultant in health protection at UKHSA South West, said: “ Everyone reacts to odours differently, and some people are more sensitive to environmental odours than others.
“Landfill gas contains hydrogen sulphide, which even in very small quantities produces a strong smell similar to rotten eggs. This gas can seep into the surrounding air and could be noticeable to nearby residents.
“Whether an odour poses a health risk depends on the concentration of a substance in the air, how frequently a person is exposed to it, and how long that exposure lasts.
“Certain groups may be more sensitive to the effects of environmental odours, including people with respiratory conditions such as asthma or COPD, pregnant women, children and older adults.”
Ms McCann said that odour and health impacts were assessed in different ways.
“The human nose is very sensitive to smell and can detect gases such as this even in very small amounts, well below what would be directly harmful to health.
Some people may experience physical symptoms such as nausea, headaches, or dizziness as a reaction to strong odours, and as concentration levels increase, more people are likely to experience symptoms.”
Business Live understands that Wiltshire Council Environmental Health team is also monitoring the odour for “statutory nuisance and public health”.




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