PM dispersion during stable winter episodes in tehran and effect of governmental emission regulations

Özet

Tehran is one of the most polluted cities in Middle East which during winter extremely high levels of particulate matter (PM) occurs due to frequent stable weather episodes. This study aims to identify major sources of PM and quantify effectiveness of possible control measures and strategies during these episodes. The Brute Force Method (BFM) with Community Multiscale Air Quality model (CMAQ) was implemented to estimate the contributions from major local anthropogenic sources on PM levels. In this regard several scenarios including the effect of existing governmental policies and regulations to upgrade vehicles emission standards were investigated. Emission due to the existing condition and future scenarios were estimated and effect of them on concentrations were modeled. Major local contributors were found to be transportation, energy and residential sources with the contributions of 64%, 15%, and 11%, respectively. The major governmental regulation to upgrade vehicles standard could led up to average of 35% PM concentration reduction during these stable weather episode. It is estimated that a set of scenarios could result in a goal of about 10% reduction in overall pollutant emissions, including both primary PM and precursor pollutants such as sulfate, nitrate and ammonium species. Our results show primary pollutants reduction led to average 8.4% reduction in aerosol levels, whereas precursor gaseous reduction could led to less than 1% PM concentration reduction. The results emphasize the need for control strategies focusing on primary particulate emission and transportation source.