Cheshire East Council has apologised after admitting its air quality figures were deliberately tampered with for three years.
In a statement, the local authority said ‘deliberate and systematic manipulation' of the data from its air quality monitoring stations took place between 2012 and 2014.
The statement follows an external investigation after concerns were raised at cabinet last year.
According to the council, the investigation found incorrect air quality data was submitted to the Department for the Environment, Food and Rural Affairs.
The council's director of planning and sustainable development, Sean Hannaby, said: ‘On behalf of the council, I would like to sincerely apologise in respect of these findings.
‘We would like to assure everyone that we have done everything we can to rectify these failings.
‘We appreciate that it has been a year now since we first reported these concerns, but it was important that we ensured a thorough review and investigation into this important matter.
‘Significant work has been undertaken to ensure that there are now robust processes and procedures in place.'
