Reasoning on and measuring small scale spatial gradients close to coke oven batteries; outdoor and indoor BTEX concentrations and PAHs depositions

1. Introduction Anomalies in concentration of outdoor benzene were detected during 2010 and 2011 by the Friuli Venezia Giulia regional environmental agency [1,2] in the framework of a monitoring programme of fugitive emissions from coke oven batteries of a steel plant in Trieste. 2. Material and Methods We report about an observational study on the presence of benzene and toluene in samples from outdoor and indoor air collected in proximity of houses far up to one km from the coke oven. The air sampling is performed with cheap and accurate [3] radial symmetry diffusive samplers, that were analyzed by thermal desorption and gas chromatography coupled to mass spectrometry [4]. Six dwellings are considered for sampling outdoor air, each being at different distances from the coking plant, a potentially relevant source of benzene emissions; five of these houses belonged to non-smokers citizens are considered for indoor sampling. The samples were collected weekly for one year starting from May 2012, and each sampler was exposed to air for 4-6 days, with duration and temperature accurately recorded. A rural background site is also considered for sake of comparison. 3. Results and discussions Summer samples showed a clear gradient of benzene concentrations decreasing from houses close to the industrial plant laying by the sea, towards inland; during winter the gradient was less evident, due to (a) the lack of sea breezes bringing emissions towards the residential area, (b) the presence of another diffuse less intense source of benzene, biomass burning; (c) reduction of the industrial activities due to the crysis. Seasonal relationships between outdoor and indoor benzene are presented. Further spatial heterogeneity is shown for wet and dry depositions where PAHs are also measured. Morover the regional environmental agency recently highlighted compatible gradients for outdoor air PAHs, by means of interpolation of data collected at three sites where PM10 is sampled. 4.Conclusions The study shows the relevance of using available analytical information, identifying proper monitoring stations and the need to assess exposure of most critical sub-populations: in some pollution studies knowing the “average” condition may be poorly informative. Bibliography [1] Dip. Provinciale di Trieste, CRMA-ARPA FVG “Qualitá dell’aria della cittá di Trieste anno 2010 - redatta sulla base dei riscontri analitici forniti dalla rete di monitoraggio” Trieste 21/10/2011 [2] Dip. Provinciale di Trieste, CRMA-ARPA FVG “Qualitá dell’aria della cittá di Trieste anno 2011 - redatta sulla base dei riscontri analitici forniti dalla rete di monitoraggio” Trieste 21/10/2011 [3] P. Bruno, M. Caputi, M. Caselli, G. de Gennaro, M. de Rienzo “Reliability of a BTEX radial diffusive sampler for thermal desorption: field measurements” Atmospheric Environment Volume 39, Issue 7, March 2005, Pages 1347–1355 [4] EN 14662-4:2005 Ambient Air Quality –Standard method for the measurement of benzene concentrations – Part 4: Diffusive sampling followed by thermal desorption and gas chromatography