Air quality at a local school affected by odours from a landfill site has exceeded World Health Organisation guidelines.

Public Health Wales (PHW) is continuing to evaluate air quality data around Withyhedge landfill site to improve understanding of the potential for harm to health of people living in the area.

The air quality monitoring began earlier this year, after Natural Resources Wales (NRW) received large numbers of complaints from members of the public about smells linked to the site.

Public Health Wales said that its most recent health risk assessment, relating to air quality data collected at the Spittal School monitoring station between October 1 and November 3 show that there were occasions when hydrogen sulphide concentrations in the air were above the World Health Organisation (WHO) odour annoyance guideline value of 5ppb / 7ug/m3.

Hydrogen sulphide is a colourless gas with an eggy smell, 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.

Other sites monitored between September 7 and 22 did not record any occasions when hydrogen sulphide concentrations in the air were above the WHO odour annoyance level.

PHW said that the long-term (lifetime) health risk to residents remained low.

“However, we understand that bad smells in your community can be upsetting and even at very low concentrations, bad smells can lead to headaches, nausea, dizziness, watery eyes, stuffy nose, irritated throat, cough or wheeze, sleep problems and stress,” said a PHW spokesperson.

“This can happen even when the substances that cause the smell are not directly harmful to health. These are common reactions, and these effects should usually pass once the odour has gone.”

PHW advises closing windows and doors when smells occur to help to stop them coming inside homes. However, residents should 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 said the health risk assessment would continue to be reviewed and updated as more monitoring data is made available.

“We recognise the real stress and anxiety that local people are under as a result of these smells,” said PHW. “However, PHW does not have regulatory responsibilities or powers around the management or enforcement of a site.”

Natural Resources Wales said it remained ‘committed to ensuring that site operator RML takes all necessary steps to minimise the risk of future emissions from the site that could result in offsite odour from Withyhedge Landfill’.