TEHRAN – According to the Air Quality Control Company, Tehran’s air quality was good and excellent for 306 days during the last Iranian calendar year 1397 (ended March 20).

An air quality index (AQI) is used by government agencies 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).

Last year, 28 days of excellent air quality was reported in Tehran, while, the residents experienced clean air quality for only 14 days in the Iranian calendar year 1396 (March 2017- March 2018).

In addition, 278 days of good air quality were reported in Tehran last year compared to that of a year ago amounting to 243 days.

Moreover, 59 days of unhealthy air for sensitive groups hit the capital last year, however, the air reached a level which was unhealthy for sensitive groups for 100 days compared to the same period a year before that.

Last year, Tehraners did not breathe a single day of unhealthy air, though, 8 days of unhealthy for all groups reported for Tehran in the year 1396.

Metropolis of Tehran suffered unhealthy levels of air pollution for 9 days, in the Iranian calendar year 1395 (March 2016- March 2017).

FB/MQ/MG