engleski

HOW POLLUTED IS THE AIR IN DUGAVE (ZAGREB, CROATIA)?

During winters, residents of Dugave, Zagreb are according to media, frequently upset about the air quality in the quarter. Therefore, we investigated the air quality there with respect to particulate matter with aerodynamic diameter less than 10 μm (PM10). Hourly mean PM10 concentrations were measured over three years (2018–2020) at Dugave measuring site (ZG3, ϕ = 45.765°N, λ = 16.006°E). The site belongs to the National Network for Continuous Air Quality Monitoring (NNCAQM) and it is supposed to be representative for urban background conditions. Concentrations measured at ZG3 were compared with PM10 values that were observed at NNCAQM measuring site exposed to urban traffic (Miramarska, ZG1, ϕ = 45.800°N, λ = 15.974°E). The influence of meteorological conditions on PM10 levels at both sites was assessed based on modelled atmospheric variables, where a numerical weather prediction model ALADIN was employed. The results showed that although overall median and maximum hourly concentrations were slightly lower at ZG3, the mean concentration at ZG3 was somewhat higher than at ZG1 (30.28 and 29.28 μgm-3 , respectively). During spring, summer and fall, PM10 concentrations at ZG3 were generally similar to or slightly lower than those at ZG1, while during the winter, they were higher. This suggests that in comparison with ZG1 site, ZG3 was more exposed to: 1) effects of fossil fuel and/or biomass burning due to heating ; and/or 2) atmospheric inversions. At both sites and for all four seasons, PM10 concentrations decreased with an increase in a wind speed, where this decrease was the most pronounced for wintertime at ZG3. For both sites, an increase in the air temperature resulted in a decrease in PM10 concentrations in all seasons except summer. A decrease of concentration with an increase in temperature was most prominent for winter, and this drop was more significant for ZG3 in comparison with ZG1 site. This further confirms our hypothesis that wintertime pollution at ZG3 was more affected by emissions associated with burning due to heating and/or unfavorable microclimatic conditions than ZG1 site. Conversely, in summer, PM10 concentrations at both sites increased with an increase in the air temperature. This points to the role of photochemical reactions in particle formation. Accordingly, this increase was more pronounced at the urban traffic site, that is, at the site where higher emissions of particulate matter precursors is expected. At both sites, the daily PM10 concentration limit value given by EU legislative (50 μgm-3 ) was exceeded more frequently than permitted, that is, more than 35 times in a year. Thus, at ZG1, 59 and 36 days with the mean concentration above the limit were observed in 2018 and 2019, respectively. At ZG3, the exceedance was even more frequent and it was found for all three years. Daily values above the limit were observed 56 and 63 times for 2018 and 2019, respectively. For 2020, the November and December data were missing. Still, during the available 10-month period, daily concentrations above the 50 μgm-3 limit were observed 37 times.

particular matter, urban air quality, traffic, heating

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