In a statement on Sunday, the country’s department of environment said large volumes of pollutants entered the capital’s atmosphere following attacks by the United States and Israel on fuel storage facilities.
The agency urged residents of Tehran to avoid unnecessary outdoor activities and remain indoors as much as possible to reduce exposure.
According to the organisation, the chemicals could combine with rainfall to produce highly acidic precipitation capable of causing chemical burns and severe lung damage.
Authorities advised residents to stay indoors, wear face masks if available and keep doors and windows closed as thick black smoke continues to blanket parts of the city.
The Red Crescent also cautioned citizens to avoid contact with any rainfall following the incident, noting that early reports described rain droplets as “black and oily”.
