Mortality assessment attributed to long-term exposure to fine particles in ambient air of the megacity of Tehran, Iran.

Few studies regarding the health effects of long-term exposure to particulate matter with an aerodynamic diameter of 2.5 μm or less (PM _2.5 ) have been carried out in Asia or the Middle East. The objective of our study was to assess total, lung cancer and chronic obstructive pulmonary disease (COPD) mortality attributed to long-term exposure to PM _2.5 among adults aged over 30 years in Tehran from March 2013 to March 2016 using AirQ ⁺ software. AirQ ⁺ modeling software was used to estimate the number of deaths attributed to PM _2.5 concentrations higher than 10 μg m ^-3 . Air quality data were obtained from the Department of Environment (DOE) and Tehran Air Quality Control Company (TAQCC). Only valid stations with data completeness of 75% in all 3 years were selected for entry into the model. The 3-year average of the 24-h concentrations was 39.17 μg m ^-3 . The results showed that the annual average concentration of PM _2.5 in 2015-2016 was reduced by 13% compared to that in 2013-2014. The annual average number of all natural, COPD, and lung cancer deaths attributable to long-term exposure to PM _2.5 in adults aged more than 30 years was 5073, 158, and 142 cases, respectively. The results of all three health endpoints indicate that the mortality attributable to PM _2.5 decreased yearly from 2013 to 2016 and that the reduced mortality was related to a corresponding reduction in the PM _2.5 concentration. Considering these first positive results, the steps that have been currently taken for reducing air pollution in Tehran should be continued to further improve the already positive effects of these measures on reducing health outcomes.