Personal exposures and microenvironment concentrations of 30 target VOCs we
re measured for 401 participants living in five European cities as a part o
f the EXPOLIS (Air Pollution Exposure Distributions within Adult Urban Popu
lations in Europe) study. Measurements in Basel used an active charcoal (Ca
rbotech) adsorbent as opposed to the Tenax TA used in the other study centr
es. In addition, within each centre, personal and microenvironment VOC samp
ling required different sampling pumps and, because of different sampling d
urations, different sampling flow rates. Thus, careful testing of the sampl
ing and analysis procedures was required to ensure accuracy and comparabili
ty of collected data. Monitor comparison tests using Tenax TA showed a mean
VOC concentration ratio of 0.95 between the personal and microenvironment
monitors. The LODs for the target VOCs using Tenax TA ranged from 0.7 to 5.
2 mug m(-3). The LODs for the 14 target compounds quantifiable using Carbot
ech ranged from 0.9 to 3.2 mug m(-3). Tenax TA field blanks showed no remar
kable contamination with the target VOCs, except benzaldehyde, a known arte
fact with this adsorbent. Thus, the diffusion barrier system used prevented
contamination of Tenax TA samples by passive diffusion during non-sampling
periods. Duplicate and parallel evaluations of the Tenax TA and Carbotech
showed an average difference of <17% in VOC concentrations within the sampl
ing methods, but a systematic difference between the methods (Tenax TA:Carb
otech concentration ratio = 1.18-2.36). These field evaluations and quality
assurance tests showed that interpretation and comparison of the results i
n any VOC monitoring exercise should be done on a compound by compound basi
s. It is also apparent that carefully planned and realised QA and QC (QA/QC
) procedures are needed in multi-centre studies, where a common sampling me
thod and laboratory analysis technique are not used, to strengthen and simp
lify the interpretation of observed VOC levels between participating centre
s.