Changes in PM10 concentrations in three automatic monitoring stations in Bourgas, during the period 2010-2016 are studied. It has been shown that the overall trend in the city is to reduce concentrations of PM10, but the significant reduction of concentrations in two stations (Meden rudnik and DOAS) is accompanied by their increase in the third station (Dolno Ezerovo). The number of days with hazardous concentrations of PM10 at Dolno Ezerovo station, exceeds national annual air quality standards during the period under consideration, and after 2012 the average annual PM10 concentration limit is exceeded, also. The relationship between PM10 concentrations and meteorological conditions (wind, visibility, temperature, humidity, sea surface pressure) over the whole period are studied. Additionally, the days with low visibility conditions (fog, mist, haze) are investigated separately. It has been shown that concentrations of PM10 in days with reduced visibility, exceed the average concentration for the period 2010-2016 by up to 80%. The most favorable conditions for exceeding the daily PM10 standard are SW-W winds with a speed of up to 4 m s −1, atmospheric pressure above normal and low air temperature.

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