Our Changing World - Pollen Forecasts

Sneezing, itchy eyes and runny noses mean one thing - spring is here. During spring and summer, pollen produced by trees, weeds and grasses leads to hayfever in those folk with pollen allergies. To help sufferers cope, Metservice posts daily pollen forecasts on its website, and Alison Ballance is off to find out how it's created.