In the capital, levels had reached 260 in the past 24 hours with other areas exceeding 300, entering the 'hazardous' category, the highest state of alert in the country's pollution indexes which range between zero and 500.
Health officials have advised people with existing medical conditions, children, and pregnant women to avoid outdoor exposure.
In neighboring Alborz province, conditions have worsened further. Kamran Haghi, acting head of the provincial meteorological office, confirmed that air quality in most areas had entered the hazardous category overnight.
“Pollution levels in parts of the province surpassed 300, and strong winds carrying dust will continue through the end of the week,” he said. He urged residents to keep windows shut and use filtered masks.
Mohammadreza Fallahnejad, acting director of Alborz’s crisis management office, linked the deterioration to low seasonal rainfall. “With reduced precipitation this year, the situation is intensifying each day,” he said.
The provincial environmental department has called on hospitals and emergency services to prepare for a rise in respiratory cases.
The recent dust affecting the country stems from both domestic and foreign sources, which operate independently of each other, said Behzad Raygani, acting secretary of the National Headquarters for Dust Storm Policy and Coordination, as reported by Tasnim.
“Part of this dust has entered from Syria and parts of Iraq, impacting our western provinces and parts of the central region. These sources have become particularly active in Syria,” he added.
“Aside from the western half and parts of central Iran, most provinces are dealing with dust due to internal and local sources.”