A Different March in Tehran: Sunshine and Blue Skies

Tehran residents had some relief with clean air and blue skies in March compared to the same month last year, data from Tehran Air Quality Control Company shows. 
Charts published on TAQCC website, airnow.tehran.ir, show that in March, the capital breathed less polluted air. 
The air was clean with blue skies for almost half the month with the Air Quality Index in 'good' condition for 13 days. 
The index compartmentalizes conditions according to 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).
Tehran saw 18 days of 'moderate' air quality, with the AQI swinging between 51 and 100.