PATTERNS OF ATMOSPHERIC NITROGEN-DIOXIDE IN KELOWNA, BRITISH-COLUMBIA

Prior to 1994, atmospheric monitoring in the central Okanagan Valley r egion of British Columbia (BC) was restricted to ozone analysis and sp oradic determinations of total suspended particulates, and dust. In Ma y 1994, a BC Government air monitoring station measuring PM10, CO, NOx , O-3 and SO2 was installed in the city of Kelowna. To complement the data obtained at this fixed location this study measured the spatial d istribution of nitrogen dioxide gas at various locations throughout Ke lowna. Twelve sites were chosen for a twelve month monitoring program (June 1994 to May 1995). Sampling, over 7 to 10 day periods, was carri ed out using Palmes passive diffusion tubes; analysis of the trapped N O2 was determined spectrophotometrically. Estimates of mean accuracy ( -4 %), and precision (standard deviation +/- 8%), were determined by c omparing diffusion tube data with that obtained by the monitoring stat ion. Average daily NO2 concentrations varied from 8 to 79 mu g/m(3). H igh concentrations of NO2 were measured in late July 1994 coincident w ith a nearby large forest fire. The highest overall values were obtain ed adjacent to Highway 97, the main traffic route, during a period of stagnant air conditions in late November and early December 1994. Aver age annual mean values ranged from 21 mu g/m(3) to 50 mu g/m(3), well within the Canadian and US (NAAQS) air quality objectives. The data ob tained in this study provides a suitable base from which future compar isons of NO2 levels, and air quality trends, may be assessed.