A severe dust storm, which had already choked several western Iranian provinces, swept eastward on May 15, reaching as far north as the capital city of Tehran in a dense cloud of dust around midday, Shargh daily reported.

Videos circulating online depicted a haze blanketing the Tehran skyline. The storm initially impacted Alborz Province, located to the west of the capital, causing trees to topple due to strong winds. It then continued its trajectory towards Qom Province.

Just a day prior, the concentration of dust particles in the western provinces of Kermanshah, Kurdistan, and Ilam had reached hazardous levels, severely impacting air quality.

According to the latest analysis from the Iranian Meteorological Organisation, a vast swathe of the southwest, west, northwest, and central regions of Iran was forecast to experience a very severe dust phenomenon on May 15.

This significant dust system originated in the desert regions of neighbouring Saudi Arabia. Carried by west-northwest air currents, it has moved across the country, profoundly affecting air quality and the daily lives of residents in the impacted areas.

The concentration of delicate particulate matter less than 2.5 microns in diameter (PM2.5) in numerous metropolitan and border cities, including Ahvaz, Ilam, Kermanshah, Sanandaj, and now Tehran, is estimated to have exceeded the alarming 500-unit air quality index (AQI). This level signifies an "emergency" and a "very dangerous" situation with significant risks to public health.

Satellite observations and weather forecast maps corroborate the high speed and density of the particulate matter in the lower atmosphere. The mass movement of dust originating in Saudi Arabia first impacted the border provinces of Khuzestan and Ilam before spreading deeper into the central regions of Iran.

The authorities are also urging the use of HEPA filtered air conditioning systems in homes, offices, and vehicles to prevent the ingress of particulate matter into enclosed spaces.

Vulnerable populations, including the elderly, children, and individuals with cardiovascular and respiratory conditions, are advised to take extra precautions, remain under close care, and adhere to preventative medication guidelines provided by their doctors.

The country's meteorological organisation has issued all necessary warnings, and local authorities are reportedly on high alert and prepared to respond to any emergencies arising from the severe dust storm.