Why does hay fever occur during spring and summer?
Hay fever that occurs mainly during spring, summer or early autumn is sometimes also referred to 'seasonal hay fever'. It tends to be triggered by increased levels of pollen in the air, from grasses, trees and weeds. In contrast, hay fever that occurs all year round is also known as 'perennial hay fever'. In general, it is due to other airborne particles, such as mould, dust mites or animal hair.