Pollen levels have been so high this year that hay fever has been triggered in non-sufferers.

The Copernicus Atmosphere Monitoring Service (Cams), which is an EU weather agency, reported a rise in grass and olive pollen release and transport across southern Europe, as well as “extreme levels” of birch pollen in north-eastern regions.

Western Finland in particular had seen “extreme daily means of birch pollen” in May which “led to symptoms even among individuals without known allergies”, the agency said in its air quality update this month.

The symptoms of hay fever – sneezing, itchy eyes, a runny nose and a headache – are caused by the body producing allergic antibodies when it comes into contact with pollen.