TEHRAN – Tehran air quality index (AQI) reached an unhealthy level of pollution for 18 days during summer, according to a report published by the Tehran Air Quality Control Company.

An AQI is used to communicate to the public how polluted the air currently is or how polluted it is forecast to become.

The index categorizes conditions according to a measure of polluting matters into excellent (0-50), good (51-100), lightly polluted or unhealthy for sensitive groups (101-150), moderately polluted (151-200), heavily polluted (201-300) and severely polluted (301-500).

During the aforementioned period, 17 days were lightly polluted, while air quality on one day reached unhealthy levels which was almost dangerous for all the residents.

However, “good” air quality reported in Tehran for 74 days, but not a single day of excellent air quality.

This is while, last year over the same period 13 days were unhealthy for sensitive groups, and the rest of the 79 days remained at good levels of air quality.

But Tehraners did not breathe a single day of heavily polluted air during summer last year.

During the past three days that autumn started, AQI stayed above 150 due to PM 2.5 for almost two days and got unhealthy for sensitive groups of people.

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