Shoppers buying fruit and veg from high street favourites Aldi and Tesco have been issued a warning over fears it may have been contaminated.
Photos have emerged of notes pinned up in branches advising customers to take extra care and wash green grocery items before eating.
The MEN reports that the source of the suspected contamination is the recent Sahara desert dust cloud that blew over southern Europe.
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Spanish authorities issued "extremely poor air quality ratings" in March for a large band of the country after a mass of hot air from Africa dumped dust after crossing the Mediterranean.
Videos were posted on social media showing the sky in Spain turning a bright orange colour as the enormous cloud cloaked the country.
Now Tesco has said the dust has affected some of its Spanish crops. It has posted a notice on its website urging people to wash produce before eating.
It said: "Due to the recent winds from the Sahara Desert, a small amount of dust has settled on our Spanish crops. Please ensure you wash your fruit and veg products before enjoying. Thank you for supporting our growers and preventing food waste by continuing to buy these products."
Signs have also been spotted in Aldi stores, stating: "Please give your veg an extra rinse. Due to recent winds from the Sahara Desert, a small amount of dust may have settled in some of our packs.
"Thank you for supporting our growers and helping to reduce food waste by continuing to buy these products."
The dust cloud moved across Europe in mid March. People reported glowing orange skies.
The mass of hot air and orange hue was strongest in Murcia and Madrid - with images taken from the streets below showing the eerie phenomenon lighting up the skies. Spanish officials warned the public to wear face masks while outside and to stay indoors for as long as possible.
People found the streets and their cars covered in a bright orange dust. People in Spain were urged to wear face masks if they went outside and to avoid outdoor exercise.
