Air Quality in Tehran Did Not Improve Even for 1 Day in Oct.

The Iranian capital’s residents inhaled more polluted air in October compared with the same period of last year, data from Tehran Municipality show.
Charts regularly published by Tehran Air Quality Control Company’s website, Airnow.tehran.ir, illustrate that Air Quality Index did not enter the range of good air quality even for a day.
AQI 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). 
According to the data, air quality was unhealthy for the sensitive group for 14 days in the month, hovering between 101 and 150.
This vulnerable group of people, including the elderly, cardiovascular and respiratory patients, pregnant women and children, was advised to limit their outdoor activities and stay home. 
In the 17 remaining days, the index remained in moderate state; AQI did not enter the 50 threshold even for a day. Analyses illustrate that the pollutant responsible for the toxic index recorded in the 14 polluted days was PM2.5—particulate matters smaller than 2.5 micrometers.