More Pleasant Air Quality Dominates Tehran in May

The residents of Iranian capital inhaled less polluted air in May compared with the same period of last year, Tehran Air Quality Control Company’s data show.
However, charts published by TAQCC website, Airnow.tehran.ir, show that the air quality index did not fall under 50. 
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). 
The company’s charts show that “moderate” status was the dominating air condition, as the index hovered between 51 and 100 throughout the month.
However, on May 29, AQI levels reached its highest of 99 due to the increasing density of pollutants.