VARIABILITY AND CAUSALITY OF PARTICULATE MATTER HIGH AIR POLLUTION EPISODES IN URBAN TERRITORY

ABSTRACT

Atmospheric aerosol fractional and morphological specifics usually depend on their place of origin, they can be solid, liquid or in mixed form. Knowing diversity of aerosol sources, life cycle, ability to be involved in physical and chemical reactions and tendency to accumulate at the specific meteorological conditions, atmospheric pollution levels can be raised and exceed either national or international standards causing adverse health effects. This study was done in order to understand and explain aerosol (PM10) concentration variability in street canyons, heavily influenced by traffic, other human activities and meteorological factors. Detailed analysis of individual episodes were performed in context of meteorological factors and other atmospheric gas (NO, NO2, NOx, CO, O3, VOC) measurements, to determine the impact of the unfavorable effects on variability and causality. While long term particulate measurements in many European cities, also in Riga (Latvia), show significant negative trend or slight stability, results of high pollution episode analysis show that results become more dense, often pollution levels rapidly raise and are stable for a whole day. Source analysis show substantial influence of site specific human activities, e.g. street sanding during winter. In some particular cases street sanding could initiate increase by almost 150 % (from 53 ug/m3 to 132 ug/m3) for PM10.

Keywords: particulate matter, urban pollution, high pollution episode, street canyon, street sanding