In this study an optimized gas chromatography negative chemical ionization mass spectrometry method was developed for analyses of target pesticides including chlorpyrifos, diazinon, endosulfan (α- and β isomers), gamma-hexachlorocyclohexane, malathion, pentachloronitrobenzene and endosulfan’s degradation product endosulfan sulfate. Chromatography was performed on a DB-5 MS + DG column with helium as mobile phase. Method detection limits ranged from 1.0 to 4.0 pg/μL for the target pesticides. This study provided the first detection of all the selected pesticides in atmospheric samples collected at Osoyoos, British Columbia. Of the organochlorines, the highest atmospheric concentrations in 2011 and 2012 were observed for α-endosulfan. The maximum concentration for α-endosulfan, β-endosulfan and endosulfan sulfate were 7.94 × 103 pg/m3, 1.94 × 103 pg/m3, and 3.34 × 102 pg/m3, respectively observed during the August 22 to 31, 2011 sampling period. The maximum concentration for α-endosulfan, β-endosulfan and endosulfan sulfate in 2012 were 6.22 × 103 pg/m3 (sampling period: May 31-June 1), 2.53 × 103 pg/m3 (July 5-18), and 6.55 × 102 (May 31-June 1) pg/m3, respectively. The highest concentration of gammahexachlorocyclohexane detected at Osoyoos sampling site in 2011 was 84.1 pg/m3 with detection frequency of 9.68%, while the detection frequency in 2012 dropped to 0% which was expected as lindane use was terminated in Canada on December 31, 2004. The highest concentrations of pentachloronitrobenzene in 2011 and 2012 were 3.57 × 102 pg/m3 (July 24), and 1.12 × 102 pg/m3 (September 5-7) respectively. For organophosphorus pesticides the highest frequency of detection was observed for chlorpyrifos (100% detection frequency in 2011 and 90.9% in 2012). The highest atmospheric concentration of organophosphorus pesticides was observed for malathion (2.33 × 104 pg/m3, June 28-July 6, 2011 and 5.44 × 104 pg/m3, July 5-18, 2012). Maximum concentrations of chlorpyrifos and diazinon were observed earlier in the agricultural season than for malathion. The highest atmospheric concentrations of chlorpyrifos were observed during April 29-May 6, 2011 (2.88 × 103 pg/m3) and March 38-April 11, 2012 (3.84 × 103 pg/m3). The highest atmospheric concentrations of diazinon were observed during May 18-25, 2011 (1.54 × 104 pg/m3) and June 10-11, 2012 (1.29 × 104 pg/m3).