TOXIC levels of underground gas seeping into homes is set to force 62 families into temporary accommodation for up to three months.
An entire estate in Gorebridge will have to relocate while engineers move to stop carbon dioxide gas leaking into properties from mothballed coal mines.
Council chiefs have warned that the homes were built in 2009 without any membranes – a protective layer that blocks out dangerous gases.
The news comes nine months after poisonous levels of carbon dioxide entered homes in Newbyres Crescent, causing two people to seek hospital treatment.
Believed to originate from coal mines, the gas is said to have penetrated homes due to a 25-year build-up of pressure.
Families have been told they need to move out by this month but it is not yet known where they will be rehoused or when they will be able to return home.
A team of council staff and public health experts from NHS Lothian and Health Protection Scotland is at work while temporary accommodation for residents is arranged.
Midlothian Council leader Owen Thompson said: “We recognise how unsettling this situation and regret not being able to provide more specific information at this time, but felt it was important to let people know as early as possible that this is likely so that we can help to support them and plan ahead for this in order to try and minimise the disruption to their lives.
“In the meantime, public health experts have confirmed we’re doing the correct things to support residents and that people can remain in their homes while final decisions are made on how we’ll bolster protection for these homes.”
An emergency response team is poised to react to complaints from residents who can call on a special hotline. All properties in the estate have been fitted with carbon dioxide detectors, while air quality monitors have been deployed.
Christine Grahame, MSP for Midlothian South, Tweeddale and Lauderdale, said the local authority was guilty of “mismanagement” and added that there had been a hands-off approach that was only now changing. “For ages I have asked for there to be an on-site information hub that residents can visit and have their questions answered,” she said.
“They have finally done that. You can’t just stick leaflets through people’s doors. A lot of the panic, distress and anxiety may have been avoided if this had been handled better.
“People aren’t blaming the council for the gas, they are blaming them for how it has been handled.”