PM10, CO and NOx concentrations in the Tuhobic road tunnel, Croatia

Particulate matter (PM 10 particle fraction) and trace gases (CO, NO and NO2) have been sampled during six weeks in the Tuhobic road tunnel, Croatia, whose length is 2140 m. Eight mini portable air samplers (Air Metrics. USA) were placed in the centre of the tunnel at a height of 1.70-m above the ground. PM10 samples were collected on Whatman quartz filters with the diameter of 47 mm, while gases were collected in Tedlar bags. Diurnal variations of pollutant concentrations for weekends and weekdays were determined based on cumulative eight- and four-hour sampling intervals, respectively. Results revealed the dependence of air Pollution levels on both. the traffic density and pollution history, i.e., traffic density in times prior to the Lime interval concerned. The highest correlation between PM 10 and trace gases concentrations was found for NO2, while among the trace gases NO and CO were the best correlated.