The yellow dust which some car owners have spotted on their vehicles in recent days is not Saharan sand, as many expected, but pollen, experts have told RTL Nieuws.

And that means these are difficult days for hay fever sufferers, according to Buienradar meteorologist Marc de Jong.

The sun and warm weather means the pollen has been hanging in the air for longer than usual and the easterly wind has further compounded the problem by bringing in pollen from Germany, he said.

Much of the yellow dust comes from birch and alder trees, but grasses are now coming into flower and this will make the problem worse for hay fever sufferers in the coming days, according to pollen monitoring website Hooikoortsradar.nl.

This weekend the wind will turn northerly and that will reduce the problem somewhat. Rain would be the best solution, but there is none on the radar until well into May, weather forecasters say.

Last month, researchers at Leiden teaching hospital warned that hay fever symptoms could be mistaken for coronavirus.

COVID-19 symptoms include a runny nose, coughing, a sore throat and a temperature. Hay fever patients suffer from a tickly cough, runny nose, streaming eyes and fits of sneezing.