Abstract
An automated measurement system is developed to monitor Peroxyacetyl Nitrate (PAN). This systemis made of an automatic valve device and a gas chromatograph with a 63Ni electron capture detector. A 5ml airsample is directly introduced in the gas chromatograph without any focusing process. Continuous measurements of PAN concentration were made in Sapporo from July 1997 to April 1998. Medianconcentration of PAN for each month show seasonal variation with a maximum of 0.37ppb in spring. Thisvariation resembles background PAN variation measured in England. However on warm sunny days in summer, PAN showed a distinct diurnal variation and local formation of PAN was apparent. Whereas, in spring andwinter, PAN concentration showed little diurnal variation. Moreover monthly maximum concentration in springwas as high as that in summer. During winter and spring, it is so cold in Sapporo that PAN production in theurban atmosphere is rather limited. Thus variation of PAN concentration during winter and spring is affectedby large scale air pollution.
