Summer ozone concentrations in Zagreb area.

Ozone concentrations were measured at three sites in Zagreb (Croatia) in the summer of 2005. Two measuring sites were in urban areas, while the third site was in a rural area about 30 km to the south from the centre of Zagreb. Hourly ozone averages varied between 1 microg m(-3) and 209 microg m(-3). Average concentrations were the lowest in the rural area, even though elevated concentrations were recorded occasionally. However, the weather conditions during measurements were untypical for that time of the year; over the summer of 2005 there were many rainy and cloudy days. Ozone concentrations at all three sites were the highest on Saturdays and Sundays, and the lowest on Thursdays. All the results were analysed with regard to the meteorological conditions (wind velocity and direction, temperature, relative humidity).