The pollen count is measured according to the number of pollen grains per cubic metre of air. The pollen count forecast can help you to judge if your hay fever symptoms will be particularly severe on any given day. As a general guide, the pollen count tends to be lower on rainy days and higher when it’s hot and sunny. The forecast is usually given as low (L), which means the count is expected to be below 30, moderate (M), 30 to 49, high (H), more than 50 or very high (VH), over 150. If you are anything like a lot of hay fever sufferers, then you might start to experience symptoms when the count reaches moderate. Counts will be higher near to large sources of grass pollen including hay meadows but city dwellers may suffer more thanks to pollution which can exacerbate symptoms.