applying epa’s instruction to calculate air quality index (aqi) in tehran

Introduction: this study aimed to calculate and evaluate air quality index (aqi) in tehran according to the epa’s instruction, and evaluate the obtained values. materials and methods: the study period included three years of 2013, 2015, and 2017 within the six-year period of 2013-2017. the concentrations of six studied pollutants were acquired from department of environment (de) and air quality control company of tehran (aqcc). epa’s method was applied to calculate aqi values during the study period, selecting the highest aqi value among all of the pollutants and monitors. results: the three-year average of aqi was about 147. during all the three years, the air quality had never been in a “good” condition (aqi<50). about 92%, 91%, 87% of aqis indicated the conditions unhealthy for sensitive groups (100