Tehran Air Quality Improves in April

In April, Tehran’s residents experienced some relief after air quality index (AQI) improved in comparison with the same month of last year, according to data from Tehran Air Quality Control Company. 
Charts published on the TAQCC website, Airnow.tehran.ir, show that in April, air pollution declined in the capital. 
Bright blue skies were observed for almost half of the month under review, as the air quality index was in “good” condition for 13 days. 
The index classifies conditions according to a measure of polluting matters: good (0-50), moderate (51-100), unhealthy for sensitive groups (101-150), unhealthy (151-200), very unhealthy (201-300) and hazardous (301-500).