Tehran’s air reached the unhealthy for sensitive groups range on Friday as pollutant concentrations climbed and meteorologists issued an orange alert for six major cities, warning that stagnant conditions could drive indices toward the dangerous threshold in the coming days.
The 24-hour average for fine particulate matter (PM2.5) stood at 103 on Friday, placing the capital in the category affecting children, the elderly and people with heart or respiratory conditions, the Tehran Air Quality Control Company said.
Morning readings reached 133, extending the hazard to a broader segment of vulnerable residents.
The US EPA Air Quality Index uses six color-coded categories to show rising levels of pollution and health risk. It starts with Good (0–50, green), where the air poses little or no threat. Moderate (51–100, yellow) signals acceptable conditions but possible effects for a small number of sensitive people. Unhealthy for Sensitive Groups (101–150, orange) warns of heightened risk for those with respiratory or heart conditions. Unhealthy (151–200, red) means everyone may begin to feel adverse effects. Very Unhealthy (201–300, purple) marks a serious increase in health concerns. At the top of the scale, Hazardous (301+, maroon) indicates dangerous conditions where the entire population may face severe health impacts.
Prolonged stability expected to worsen pollution
Tehran, Isfahan, Tabriz, Karaj, Ahvaz and Mashhad were listed as the cities most at risk of severe deterioration.
The stagnant pattern is likely to persist, Sadegh Ziaian, an official at the National Meteorological Organization, said on Thursday.
“An increase in pollutant concentrations in the major cities is certain,” he said, adding that only parts of Iran’s eastern belt would see winds strong enough to disperse particulates. “Tehran’s sky will remain clear with local haze, and air will reach unhealthy levels for all groups.”
Public health toll and calls for systemic reform
The health ministry has repeatedly stressed the human cost of chronic pollution. 58,975 deaths in the past Iranian year were attributable to poor air quality, an average of 161 a day, with economic losses estimated at $17.2 billion, according to Deputy Health Minister Alireza Raisi.
Meteorologists advised residents and authorities to curb non-essential travel, manage fuel consumption, restrict polluting industrial activity and avoid outdoor exercise. Environmental specialists continue to urge long-delayed measures – from retiring aging vehicles to expanding cleaner energy – warning that without structural reforms, cities such as Tehran will remain trapped in cycles of hazardous air and mounting health impacts.
