One person is in a stable condition at the Midland Regional Hospital, Portlaoise after becoming unwell while at the Electric Picnic Festival in Stradbally.
It is understood that local emergency services responded to a call just before 7am.
The call was made after concerns over the possible leaking of carbon monoxide from a faulty generator on a privately hired specially converted double decker bus.
A garda spokesperson said that two people had been brought to hospital initially, but one was later released.
