Hay fever could be costing British businesses up to £7.1 billion a year as research reveals over a third of sufferers cannot concentrate due to the condition.

The research, commissioned by Kleenex, also revealed that 39 per cent of people questioned were only able to function at 63 per cent of their usual productivity levels when they were suffering from the condition.

Perhaps most worryingly for employers concerned about employee health, 87 per cent of sufferers said they were unable to operate at “maximum capacity”.

Commenting on the results of the survey, Jean Emberlin, director of the National Pollen and Aerobiology Research Unit, said: “With almost a quarter of our entire workforce being affected by hay fever these figures give us real cause for concern – particularly as businesses struggle to achieve maximum efficiency in the recession.”

Some 30 per cent of employers admitted they had never thought about helping staff during hay fever season.