Pollutants Return to Haunt Tehran’s Skies

After several consecutive months of air quality improvement, the skies of Tehran once again were tainted with pollution in June. 
According to data released by Tehran Air Quality Control Company, residents of the capital breathed more polluted air in the month, compared with the same period of last year. 
Charts published on TAQCC’s website, Airnow.tehran.ir show that clean blue skies were not seen at all in June, meaning that the air quality index never went below 50 showing "good" condition. 
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).