SummaryA recently developed diffusive sampler, intended for use in long-term ambient measurements of volatile aromatic hydrocarbons, has been tested to determine the upper limits of its sampiing capacity. A test has been performed over 12-month period to evaluate these limits in terms of its 'internal consistency' (i.e. checking if the sum of the amounts of a given pollutant, determined over shorter consecutive periods, matches the amount determined from a single long-term exposure). Results demonstrate that the uptake rate of the device, in a real (indoor) atmosphere, is constant for approximately 8 months for benzene and for approximately 10 months for toluene. The upper limit for hig her homologous species was not reached after exposure for a year to typical ambient concentrations. This means the device can be successfully used for several months, thereby enabling low-cost determinations of ambient BTX concentrations.
Results from a five month monitoring campaign of BTX (benzene, toluene and the sum of ethyl benzene, o-xylene, m-xylene and p-xylene), performed at Monterotondo, a little town 23 km NE of Rome, and correlation of the measured concentrations with meteorological and natural radioactivity data are presented and discussed. This campaign allowed us to extrapolate a pattern of the annual distribution of benzene in the town. A map, showing the average distribution of pollutants, is presented, as a useful tool to manage an appropriate policy of air pollution. A contemporary indoor-outdoor investigation has been performed at five homes and two classrooms of Monterotondo and at thirteen homes and thirteen classrooms in the outskirts of Rome. Non-smoking people and low polluted sites were chosen for this campaign, in order to highlight if commonly used domestic materials could act as internal sources. Data, obtained by employing long-term diffusive samplers, are compared with a parallel experiment showing the day-night indoor-outdoor trend. The obtained results, confirmed through statistical analysis of data, let us conclude that there is evidence of internal sources at homes whilst, in the schools, depletion phenomena prevail, probably due to the walls adsorption.
SummaryA molecular diffusion-based sampling device (known as Analyst 2) is presented for the determination of semi-volatile polyaromatic hydrocarbons (PAH's) in air. It has been developed from a previous model (i. e. Analyst), which was suitable for volatile hydrocarbons. The new model is capable of collect enough gaseous PAH's to allow GC-MS analysis of enriched samples after I',,vo-month exposition to either urban or suburban air. The adsorbing material adopted for enriching the PAH's, i. e. Carbopack C, allows good recoveries of analytes ranging from naphthalene to chrysene, when only a single solvent extraction is run at ambient temperature. Some field experiments generated gaseous PAH concentrations that were in agreement with those expected at urban and suburban sites.
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