Zuckerman Postdoctoral Scholar at the Weizmann Institute of Science, Dr. Alexandra Lai, publishes new research findings in Atmospheric Pollution Research Journal.
Each year, considerable levels of dust particles coming from arid regions of the earth contribute to the atmosphere. Because dust has serious environmental and human health effects, predictions of dust concentrations and their contribution to PM surface concentrations are essential for atmospheric research and the implementation of air quality programs and rules. This study aims to assess dust contributions to PM2.5 in Tehran in order to provide guidance for air quality management systems as well as validate the updated Dust Regional Atmospheric Model version 2 (BSC-DREAM8b) and the NMMB/BSC-Dust model using chemical speciation of ground-based measurements of PM2.5. Accurate and reliable measurements are necessary to determine the sources of pollutants as well as to confirm, validate, and improve models. For this purpose, dust concentration and contribution were calculated from chemical speciation of PM2.5 samples that were obtained on a 6 day basis for a whole year from February 2014 to February 2015. The comparison of the dust observations to the model products revealed that model outputs were in good agreement for the monthly averaged values. However, for the daily averaged values, models and ground observation showed a considerable difference. In order to understand possible reasons for the discrepancy, differences between neighboring grid cells were investigated, as well as the effect of sampling frequency. It is found that agreement between models and observations was sensitive to sampling duration and frequency but not to spatial variability between grid cells. This study is the first validation of model outputs with the calculated dust concentration from ground-based chemical speciation of PM2.5 rather than using total PM or aerosol optical depth measurements as a proxy for dust concentrations.