The cost of making sure schools met national standards to reduce Covid risks in East Lothian was more than £660,000 after windows had to be replaced in four primary schools.
A report on the work carried out by the local authority to ensure classrooms had proper ventilation and CO2 monitoring so children could return during the pandemic revealed the additional work needed.
And it revealed 12 primary schools exceeded the CO2 limit introduced for the initial monitoring leading to further interventions.
READ MORE: Pupil absence 'significant' in East Lothian schools as Covid virus spreads
The council received £303,000 from the Scottish Government to fund measures introduced to reduce the spread of the virus and ensure schools were monitored for CO2 levels.
The final bill included around £500,000 which was needed to replace windows in four primary schools which failed to meet the standards.
A council spokesperson said the extra funding came from the council's capital programme and work on the windows would have been picked up in condition surveys and planned works in the future.
They said: "While the works have been undertaken in response to COVID-19 and as part of the essential mitigations that have been required of all schools, the investment we have made in new windows and enhanced ventilation as necessary will benefit East Lothian’s schools for many years to come."
A report on the work undertaken by the council to meet national requirements in schools said 700 mobile CO2 monitors were initially bought in September last year and distributed to schools and early learning and childcare partners.
It said: "The majority of learning and teaching spaces were found to have good results evidencing that the use of natural ventilation was being effective in reducing CO2 levels below 800ppm."
However it said 12 primary schools found at least one area where reading exceeded the 1200ppm set as the limit before intervention was required.
It added that measures taken to tackle schools which went over the limit included "freeing off windows, obtaining costs to fit ventilated roof lights, overhauling window mechanisms, giving instruction on the use of trickle ventilation, investigating options for internal rooms and upgrading mechanical ventilation to internal rooms."
Four primary schools - Cockenzie, Ormiston, St Martins in Tranent and Preston Towner in Prestonpans - required window replacement work which cost a total of £511, 211.
A second batch of 600 C02 monitors were bought in February this year to ensure all learning spaces had one across schools in the county.
The report revealed that the total cost of monitors was £146,770 however it said when the second delivery of monitors was distributed "charging via USB became an issue and Mains – USB adaptors were purchased and distributed to all areas to remedy the situation" at an additional cost of £13,000.
