Ryanair has called on the Irish and UK governments to drop what it describes as "unimplementable and ineffective" 14-day quarantine measures aimed at controlling the spread of coronavirus.
The airline said such measures are now being scrapped in most other European countries in favour of face masks and social distancing.
"14-day quarantines are ineffective and unimplementable. Requiring international arrivals to quarantine only after they have used multiple public transport providers to get from the airport to their ultimate destination has no basis in science or medicine," Michael O'Leary, chief executive of Ryanair Group said in a statement.
He said the airline strongly urges Europe’s governments, especially those in Ireland and the UK, to mandate to the wearing of face masks for airline, train and underground passengers.
"Europe’s citizens can travel safely on their summer holidays wearing face masks and observing temperature protocols," said Mr O’Leary.
The company said it welcomed safety guidelines issued by the European Union Aviation Safety Agency (EASA) and European Centre for Disease Prevention and Control (ECDC) which include the wearing of face masks during flights.
The carrier said the advice reflects its own health protocols as it returns to flying from 1 July and will allow the tourism industry to resume business in July and August.
The EASA and ECDC guidelines include the observation of physical distancing wherever possible and the wearing of a medical face mask to protect other passengers.
The organisations also recommend that passengers practice scrupulous and frequent hand hygiene.
They also say that passengers and the general population must be assured that filtered air on aircraft is safer and cleaner than many people breathe on the ground.
Testing passengers in order to allow travelling/flying under "immunity passports" is not supported by the current scientific knowledge, the document states.
Where possible, contact and touching of surfaces should be minimised using electronic alternative processes, it also suggests.
The agencies also say that access to airport terminals should be limited to passengers, crew members and staff to the extent possible.