What is Atmospheric Scavenging and How it Lead to ‘Black Rain’ in Tehran?

On Sunday (March 8th, 2026) Tehran experienced a strange phenomenon as ‘black rain’ poured into the city. Residents of the capital city of Iran observed an oily residue left behind by the rain that coated buildings, cars, and roads. People also reported about air smelling like burnt petrol and many even complained of respiratory distress and migraines. The governor of Tehran also issued a statement requesting everyone to wear a mask while venturing outside their homes.

The occurrence came in the wake of Israel attacking several fuel storage and oil facilities in the city which burned the city for several hours. But how is the destruction of oil facilities connected to the peculiar oily rains? The answer is atmospheric scavenging.

What is atmospheric scavenging?

Atmospheric scavenging is the natural process by which the atmosphere cleanses itself of airborne pollutants, such as dust, soot, and chemicals. This occurs when these particles are removed from the air and deposited onto the Earth's surface, primarily through precipitation.

As Israeli airstrikes targeted the oil facilities, it released a massive amount of oil, dust, and soot into the atmosphere. Videos and images coming out from Tehran after the attack showed black, dense clouds hanging over the city and finally when the clouds turned into rain, it brought the black, oily residue along with it.

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