FIELD COMPARISON OF 2 NO2 PASSIVE SAMPLERS TO ASSESS SPATIAL VARIATION

Two-week average NO2 concentrations were measured in Amsterdam (NL), H uddersfield (UK) and Prague (CZ) at 80 sites in each study area, to as sess small area spatial variation, using a tube type and a badge type passive sampler. The badges appeared to be less robust than the tubes. The lower detection limit for tubes and badges was 3.7 and 0.91 mu g/ m(3), respectively for fortnightly measurements. Accuracy of the sampl ers was determined with reference methods (chemiluminescence). The mea n ratio of the concentration measured by diffusion tube over that by t he reference method was 1.16, 1.03 and 0.77 in Amsterdam, Huddersfield and Prague, respectively. Standardizing the badges for the results ob tained in Amsterdam, the relative mean ratio of the concentration meas ured by the badges over that by the reference method was 0.95 and 0.58 in Huddersfield and Prague, respectively. NO2 concentrations measured by the two designs did not differ significantly. Mean NO2 concentrati ons were 36, 26 and 22 mu g/m(3) in Amsterdam, Huddersfield and Prague , respectively. The precision of duplicate tubes and badges was 8% and 11%, respectively. Both samplers are suitable for determining real va riation in small area NO2 concentrations in the ranges which occurred. It is concluded that low-cost, simple NO2 passive samplers can provid e reliable information about variation in NO2 concentrations within ur ban or rural areas on a small spatial scale. Based on its robustness a nd its precision, tubes were preferred over badges.