What is “Black Rain”?

Thick toxic smoke and reports of “black rain” have blanketed Tehran, the capital of Iran, after missile strikes damaged oil depots and refineries amid escalating conflict in West Asia.

The World Health Organization (WHO) has warned that the black and acidic rain falling over the city poses a serious health risk, particularly to respiratory health. The agency supported the Iranian authorities’ advisory urging residents to remain indoors to limit exposure.

According to WHO officials, the attacks triggered the massive release of toxic hydrocarbons, sulphur oxides, and nitrogen compounds into the atmosphere. Scientists caution that inhaling or coming into contact with the polluted smoke and rain particles may lead to:

• Headaches
• Skin and eye irritation
• Breathing difficulties

Long-term exposure to certain chemicals in the pollution could also increase cancer risk.

What is “Black Rain”?

Environmental scientists describe “black rain” as rainfall containing high levels of atmospheric pollutants. According to Farzana Kastury, an environmental scientist at the University of Adelaide, such rain typically occurs when dense smoke or combustion products mix with rain clouds.

It is often associated with:

• Bushfire smoke
• Burning of heavy fuel, a low-quality byproduct of crude oil refining

In the current situation in Iran, the black rain is likely carrying pollutants released from burning oil products, including benzene, acetone, toluene, and methylene chloride—chemicals known for their toxic and carcinogenic properties.

Sources: Nature