The influence of meteorological parameters on PM2.5 and PM10 values in Istanbul

In this study, spatiotemporal relationship between PM2.5 and PM10 concentrations and meteorological parameters were investigated for Silivri and Umraniye districts in Istanbul for 2014-2020. For this purpose, hourly PM2.5 and PM10 concentrations values of two air quality monitoring stations and meteorological data (wind speed, wind direction, relative humidity, total precipitation, minimum and maximum temperature) were examined. In all seasons, while PM concentrations were lowest at 06:00 local time (LT), PM2.5 and PM10 have peak values around 09:00 and 19:30 LT both in Silivri and Umraniye mainly due to anthropogenic activities such as vehicle exhaust emissions. In daily perspective, highest PM values were observed on Sundays in winter at Silivri. On the other side, peak PM values are shown on Fridays at Umraniye. It was found that local emission sources during low wind speeds cause the highest PM2.5 concentrations during winter months and southerly winds exceeding 8 m/s increase the PM10 levels at Silivri and Umraniye. The statistical analysis showed that PM2.5 and PM10 concentrations at Silivri were negatively correlated with wind speed with correlation coefficients of -0.56 (winter), -0.47 (autumn), respectively. Wind speed is negatively associated with PM2.5 (r=-0.48) and PM10 (r=-0.38) in winter season at Umraniye. In addition to this, relative humidity showed negative relationship with PM10 (r=-0.43) in spring at Silivri, while a positive correlation was found between PM10 (r=0.40) and PM2.5 (r=0.38) measured in the summer season and the maximum temperature. In addition to the anthropogenic factors (e.g. urbanization, transportation, and industrialization) that decrease air quality of Istanbul, local meteorological variables and atmospheric transport of pollution are observed to be the other factors that contribute to air pollution.