The National Gallery warned the OPW that diesel fumes from Leinster House’s emergency generator were billowing into its building, leading to health and safety complaints from staff.
The monthly generator tests are needed to make sure the parliament’s back-up electricity supply is fully functioning.
However, the tests have alarmed the gallery which has been forced to shut rooms filled with valuable artworks and close off public access.
Records released under FOI reveal multiple occasions where fumes entered the National Gallery’s (NGI) historic wings.
In emails, the NGI also told the OPW that staff were worried there was a health hazard from the generator testing.
In June, testing of the generator led to the closure of galleries to the public in the landmark Dublin building.
An email from the NGI’s head of operations to the OPW said: “It has not happened for some time to my knowledge, and I had thought it had been resolved.
“I understand you are working on some additional measures, but can any generator testing be undertaken outside of gallery hours until such time as the matter is remedied?”
Another message said the diesel fumes had accumulated in several rooms including the famous Shaw Room and multiple other exhibition spaces.
The email read: “Leinster House was informed, and they instructed the OPW to turn the generator off.
“The rooms were re-opened at 10.30am when the fumes had dissipated. This problem has not gone away yet.”
The NGI repeatedly asked the OPW if the testing could be carried out much earlier in the day to avoid any disruption for the public or staff.
An email said: “This has led to a number of health and safety complaints from staff at the Gallery.
“You will appreciate that addressing a H&S [health and safety] matter of this nature is very important to the gallery and as one possible solution, we are asking if generator testing can be conducted during gallery out of hours periods.”
The problematic testing had also reared its head in the summer of 2024 when a staff member took a video showing fumes rising through a grid and up towards air vents.
Several incident reports were also logged with one saying: “Today we closed rooms 14 to 20 because of a strong smell of diesel fumes from a generator in Leinster House.”
Another said: “Closed the Dargan wing to the public for one hour this morning. Diesel generator in Leinster House active causing diesel fumes to accumulate.”
Asked about the correspondence and any possible risk to staff or their art collection, the National Gallery said they had no comment to make.