Aromatic hydrocarbon and methyl tert-butyl ether measurements in ambient air of Helsinki (Finland) using diffusive samplers

The diffusive sampling method was evaluated for measuring benzene, toluene, ethylbenzene, xylenes, styrene, propylbenzene, ethyltoluenes, trimethylbenzenes and methyl tert-butyl ether (MTBE) in the urban air of Helsinki, Finland. Concentrations were measured in 2-week periods at four different sites during the year 2000. Tube type adsorbent tubes were pre-packed with Carbopack-B (60/80). Analysis was conducted using thermal desorption and gas chromatograph coupled to a mass spectrometer. In different seasons, during five diffusive sampling periods, parallel measurements were conducted using pumped and online sampling. The compared techniques agreed reasonably well for other compounds than trimethylbenzenes. Based on comparisons, diffusive uptake rates for ethyltoluenes, styrene, propylbenzene and MTBE were determined, and for trimethylbenzenes, uptake rates were revised. The concentrations of aromatic compounds in Helsinki metropolitan area were also compared to the concentrations of a rural, forested site in Central Finland.