Dander (or flakes of dead skin) from pets and other animals are a major trigger of year round allergies.

Dust allergies are actually caused by tiny insects called dust mites. They can thrive in fabrics such as carpets, bed linen and pillows, and just like pet dander and mould are a common trigger for allergy sufferers.

Mould is another common trigger of upper respiratory allergies. You will often see this fungus growing in damp poorly-ventilated conditions, such as in bathrooms. But you don't always have to see it to be affected by it.