For those who suffer from hayfever, the onset of autumn may usually be a great relief. But British scientists fear the season of sneezing and snuffling may be extended, after they found the first signs of pollen from invasive foreign plants. Common ragweed - a highly allergenic plant which emits a billion pollen grains in a single season - is already the biggest cause of hayfever in the US. It invaded the Eurppean mainland in the 1960s - brought over in contaminated seed - and has been spreading north ever since. Common ragweed is already the biggest cause of hayfever in the America and now the pollen in being found in England
@highlight
Common ragweed is already the biggest cause of hayfever in the US
@highlight
Highly allergenic pollen from the plants has been found in England
@highlight
Leicester University researchers fear hayfever season will be extended
@highlight
Deborah Waddell from Asthma UK said this will cause misery for many
One in five @placeholder people suffer from hayfever - and another one in 12 have asthma