Nova Scotia is in the air pollution outflow region of North America and experiences elevated surface air pollution episodes regularly. We present the first analysis of long-term (2000-2018) hourly ozone (O₃) and ozone precursor gas trends at three Nova Scotia provincial monitoring locations (‘urban’ Halifax, ‘suburban’ Halifax at Lake Major and ‘regional background’ at Aylesford Mountain), together with an examination of provincial ozone precursor emission trends. The precursors considered are nitrogen oxides (NO_x) and volatile organic compounds (VOC). Over the common data period for the three stations (2006-2017) the annual 99^th percentile hourly ozone concentrations decreased significantly in Halifax (-0.77 ppb/year; p = 0.02) and at Aylesford (-0.65 ppb/year; p = 0.03), in agreement with regional trends. No statistically significant changes were found in high ozone at suburban Lake Major (-0.02 ppb/year; p = 0.94), but the annual 25^th percentile, median, and 75^th percentile hourly ozone concentrations increased significantly (p < 0.01) only at this location (1.09 ppb/year, 1.23 ppb/year, 1.03 ppb/year, respectively). This is consistent with the strong NO_x-O₃ titration effect in downtown Halifax decreasing over time. After correcting for the titration effect over the full study period, the annual median Halifax total ozone is found to be decreasing (-0.45 ppb/year; p = 0.02).

新斯科舍省位于北美的空气污染外流区，经常会经历地表空气污染加剧的情况。我们首次分析了新斯科舍省三个省级监测点（“城市”哈利法克斯、“郊区”哈利法克斯在梅杰湖和“区域背景” ）的长期（2000-2018）每小时臭氧 (O ₃ ) 和臭氧前体气体趋势在艾尔斯福德山），以及对省级臭氧前体排放趋势的检查。考虑的前体是氮氧化物 (NO _x ) 和挥发性有机化合物 (VOC)。三站通用数据期（2006-2017）年度^第99^次哈利法克斯（-0.77 ppb/年；p = 0.02）和艾尔斯福德（-0.65 ppb/年；p = 0.03）的每小时臭氧浓度百分比显着下降，与区域趋势一致。在郊区的梅杰湖 (-0.02 ppb/year; p = 0.94) 的高臭氧中没有发现统计学上的显着变化，但每年^第25^个百分位、中值和^第75^个百分位的每小时臭氧浓度显着增加 (p < 0.01) 仅在这个位置（分别为 1.09 ppb/年、1.23 ppb/年、1.03 ppb/年）。这与强NO _x -O ₃哈利法克斯市中心的滴定效应随着时间的推移而降低。在整个研究期间校正滴定效应后，发现哈利法克斯总臭氧的年中位数正在下降（-0.45 ppb/年；p = 0.02）。