Levels of a potentially harmful gas emitted by a local landfill site have been above World Health Organisation guideline levels, it has been revealed.

Public Health Wales (PHW) has carried out a health risk assessment of air quality data collected between 1 March and 3 April 2024 in the area around the Withyhedge Landfill Site.

The data suggests that, at times during March and April 2024, levels of hydrogen sulphide, a colourless gas with an eggy smell, in the air around the site have been above the World Health Organization (WHO) odour annoyance guideline.

PHW said that when residents are exposed to odours at levels above the WHO guideline value, they may experience effects such as headaches, nausea, dizziness, watery eyes, stuffy nose, irritated throat, cough or wheeze, sleep problems and stress.

The public health agency maintains that reducing the cause or source of offsite odours from the landfill site must be a priority to reduce exposure and any potential health effects on the local community.

Many of the symptoms above have been reported by local residents in the wider vicinity of the landfill since last October.

Although an enforcement deadline at the site passed last month, residents are still complaining of gas and odours in their homes on a daily basis.

“These are common reactions to nasty smells, and these effects should usually pass once the odour has gone,” said PHW. “The long-term (lifetime) health risk is low.”

As a result of the risk assessment PHW is reiterating its advice residents to keep doors and windows closed when the smells are present, and to seek medical advice if they feel unwell.

PHW advises residents not to block windows or vents completely as they provide air to vent cookers or heaters and can help to control damp.

Once an outdoor smell has passed, opening windows and doors will help get rid of any smells that remain.

PHW noted that work to cap the site has now been completed and welcomed plans to position static air monitoring around the site going forward to help capture more detailed data.

Dr Sarah Jones, consultant in environmental public health for PHW said: “We recognise the real stress and anxiety that local people are under as a result of odours around the Withyhedge landfill site. Like local residents, we are very eager to see a rapid resolution to this issue.

“The health risk assessment will continue to be reviewed and updated as more monitoring data is made available to us.”

Chair of the Air Quality Group for the Multi-Agency Incident Management team Gaynor Toft said: “We note the risk assessment from Public Health Wales and continue to refine and develop the air quality monitoring programme in the vicinity of the landfill site. Suitable static monitoring locations are being identified for the siting of equipment.

“We continue to work in collaboration as the Air Quality Group to ensure that robust data is collated to inform future Public Health Wales assessments.”

Huwel Manley of Natural Resources Wales (NRW) added: “We acknowledge the report and will continue to use our regulatory powers to drive improvements on site to address causes of odour affecting the community.”

NRW gave RML, the company running the landfill site, until the middle of May to undertake several remedial actions to control the gas emissions.

The Western Telegraph has approached NRW for a detailed update on the current situation at the site.