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Air suspended particulate concentrations at Coronach were similar 

 to those obtained in past years. Saskatchewan's 24 hour average 

 standard was exceeded on two occasions in April 1987 . Weather data 

 indicates strong north winds during these days with the result that 

 wind blown dust is the likely cause of the violations. The annual 



geometric mean increased from 25 . 2 micrograms per cubic metre 



3 3 . . 



(ug/m ) in 1986 to 36.0 ug/m for the 10 month monitoring 



period in 1987, however the mean continues to be well below the 



3 

 Saskatchewan standard of 70.0 ug/m . 



Suspended particulate concentrations at Saskatchewan Power 

 Corporation's monitoring Station exceeded Saskatchewan's 24 hour 



average standard on seven occasion in 1987 . The highest recorded 



3 



value of 494.2 ug/m occurred on April 15. Weather data 



indicates strong winds from variable quadrants throughout the day 

 which suggests wind blown dust as the most probable cause. As 

 well, this portion of the province has been extremely dry in the 

 past few years with little snow cover or rainfall to prevent 

 episodes of blowing dust. The annual geometric mean recorded at 



Saskatchewan Power Corporation's particulate monitoring site during 



3 

 1987 was 34.6 ug/m . 



In-stack monitoring data obtained in 1987 were similar to the 



results of previous years. Daily nitrogen oxides concentrations 



3 

 ranged from 1465 to 2285 milligrams per cubic metre (mg/m ) with 



3 

 an average yearly concentration of 806 mg/m as compared to 



3 

 898 mg/m in 1986. Ongoing improvements to the sample 



conditioning system have considerably improved the operation of the 



nitrogen oxides monitor in the past two years. The monitor was 



operational 82 per cent of the time in 1986 and 1987 as compared 



to 387o of the time in 1985 . Daily sulphur dioxide concentrations 



3 



ranged from 1 124 to 3 975 mg/m with an average yearly 



3 

 concentration of 2 556 mg/ra as compared to 3 688 in 1986. The 



sulphur dioxde monitor was available 85 per cent of the time in 



1987. 



