Air quality monitoring stations in the namesake capital city of Tehran Province show people continued to breathe more polluted air in February, compared with the same period of last year. 

A close analysis of Air Quality Index during the period makes this very clear. AQI is used by government agencies to announce the prevailing level of air pollution, or forecast future days.

The index categorizes conditions dictated by a measure of polluting matters into good (0-50), moderate (51-100), unhealthy for sensitive groups (101-150), unhealthy (151-200), very unhealthy (201-300) and hazardous (301-500).

In February, people in Tehran did not see clear blue skies even for a single day. Instead, the moderate status was recorded for 22 days, as the index hovered between 51 and 100.

Those with respiratory disorders, cardiovascular diseases, the elderly, pregnant women and children were warned of their outdoor exposure for six days, as AQI remained unhealthy for sensitive group.

Tehran Air Pollution Persists | Financial Tribune