Indoor air quality in the most crowded public places of Tehran: an inhalation health risk assessment

Satisfying indoor air quality in public environments has become essential in cities. In the present study, indoor PM2.5, CO2, NO2, SO2, nicotine, and BTEX have been assessed in 12 categories of public places. The highest average concentrations of PM2.5, NO2, and SO2 were observed in waterpipe cafés (233, 29.6, and 5.1 µg/m3), whereas the lowest concentrations were found in health clubs and hospitals, respectively. Moreover, indoor BTEX concentration varied from 69.5 µg/m3 (passenger terminals) to 1739.2 µg/m3 (elderly care centers). Given nicotine, the highest concentrations were found in waterpipe cafés, ranging from approximately 11.0 to 50 µg/m3. The mean hazard quotient (HQ) and Hazard Index (HI) for benzene, toluene, ethylbenzene, and xylene were calculated in all types of public environments, and results showed that the amount of HQ and HI in none of the places was more than 1. Furthermore, the lifetime cancer risk (LTCR) exceeded the guideline threshold in hospitals, restaurants, elderly care centers, passenger terminals, movie theaters, and beauty salons. The findings of our study indicate that the indoor air quality in most public settings within Tehran city is not acceptable and necessitates appropriate management. These findings underscore the importance of monitoring indoor air quality and implementing effective strategies to mitigate exposure to air pollutants.