United Kingdom will witness "blood rain", which is a mix of toxic smog and dust, over the weekend.
Air pollution in Britain was already high this week, with dust from Sahara desert mingling with smog.
MeteoGroup forecaster Mario Cuellar told The Telegraph: "Blood rain is dust in rain from the Sahara."
Fine dust from Sahara desert travels over 3000 km to Britain due to heavy wind activity in the North African deserts.
Ahead of the blood rain, south-east and eastern England will witness high levels of pollution; but by Saturday, the Atlantic winds will push away the dusty wind. Though the downpour in Britain would be short-lived, similar instances in Spain and France and Scandinavia tend to last long.
UK health officials have issued a pollution warning, asking adults and children with lung or heart conditions to avoid strenuous activity. The health warning is also applicable to senior citizens and asthmatics.
The blood rain will leave a rusty brown stain over the cars and pavements.
There have also been reports of blood rain in India, where the colour was thick enough to even stain clothes.
Blood Rain in UK- Twitter Reactions
— Sara Nelson (@SaraCNelson) April 10, 2015
David Allan @davidm_allan
@paulkingstonnnp "blood rain" how ridiculously dramatic... it's rain mixed with some dust! (another nice picture though Paul).
Bath Chronicle @BathChron
Health warnings in place as Southern UK experiences #airpollution and #bloodrain
Lady FOHF @LadyFOHF
Blood rain? When do we get frogs and locusts, might arrange to be away then.
Red Rain! "Asthma warning as Saharan dust 'blood rain' hits Britain"