Black rain is falling in Iran after strikes on oil facilities. Scientists warn of long-term consequences

Scientists say the health and environmental effects of Israeli strikes on oil depots in and around Tehran could be severe, impacting water and food sources long after the smoke and black rain clears.

The World Health Organization (WHO) issued a warning Tuesday about toxic pollutants in the air after the Saturday strikes on four oil storage facilities and an oil production transfer centre sparked pillars of flames and thick, black clouds that later produced black, oily rain.

Residents in the city of 10 million reported having trouble breathing and said they experienced dizziness and burning sensations as the rain, mixed with chemicals from burning oil, fell from the sky.

"The black rain and the acidic ⁠rain coming with it is indeed a danger for the population, respiratory mainly," WHO spokesperson Christian Lindmeier told a ‌media briefing in Geneva.

The UN health agency says it has received multiple reports of black rain since the attacks, which came just over a week into the U.S.-Israeli war against Iran, and supports Iran's advisory urging people to remain indoors. 

The Iranian Red Crescent Society warned that the rain can cause serious lung damage and chemical burns to the skin.

Peter Ross, a pollution specialist and senior scientist at the Sidney, B.C.-based Raincoast Conservation Foundation, says petroleum mixtures can contain thousands of petroleum hydrocarbons including some, like benzene, that are "very, very toxic." 

"The potential for long, severe, long-term consequences is very real," he told CBC News.

When those toxic gases are dispersed into the atmosphere through fires, Ross says they pose an acute risk to humans breathing them in that "can make them very dizzy, can render them unconscious, it can kill them."

Ross says reports of people experiencing burning sensations in their eyes underscores the likelihood that the fires created sulfur and nitrogen oxides, which were the primary drivers of acid rain in the 1970s and 80s.

He says there are a number of compounds with the potential to be carcinogenic, raising concerns of longer-term health effects for residents, especially as petroleum disperses into waterways and groundwater.

Ross says people downwind and downstream of the explosions will be particularly vulnerable.

"That has potential to really seriously threaten public health and the safety of drinking water for quite a while," he said, adding it will also impact fisheries and agriculture.

Some have drawn parallels to the 1991 Kuwaiti oil fires, when the Iraqi military set fire to hundreds of oil wells during the Gulf War, causing similar black rain.