A 'pollen bomb' is set to wreak havoc across Britain this week, triggering debilitating symptoms for the nation's 13 million hay fever sufferers.The UK is on course to see record-breaking June temperatures of 38C today, and those with pollen allergies - officially known as hay fever - are being warned to brace themselves.An incurable allergic condition, hay fever can cause splitting headaches, extreme fatigue, sneezing, coughing, blocked or runny noses, itchy eyes and sore throats. And symptoms could be set to become even more severe, as the combination of sizzling 'heat dome' temperatures and 'very high' pollen levels will see huge quantities of allergy-causing pollen particles released into the air.Experts say the nature of this summer's 'stop-start' weather has created the perfect conditions for a so-called 'pollen bomb'.Normally, pollen from trees and grass are released at different times, but fluctuating conditions are believed to have caused both to overlap and release at the same time. This triggers high concentrations of pollen in the air, increasing the chance of allergic reactions when the particles come into contact with the eyes, nose, throat and mouth.Thankfully for millions, experts say there are several ways to protect yourself against the dreaded 'pollen bomb' beyond reaching for an antihistamine - the most common form of protection, which is taken in a tablet form.Read on for their top tips. A 'pollen bomb' is wreaking havoc on Britain this week, triggering debilitating symptoms for the nation's 13million hay fever sufferers