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The study reported in this paper is focused on occupational exposure to potential toxic compounds for employees working in dynamic olfactometry, following EN 13725:2003 standard procedures. Municipal solid waste (MSW) incineration plants, typically, have authorized stack emissions for primary pollutants (like CO, NOx, particulate), for selected trace organics (polycyclic aromatic hydrocarbons (PAHs) or dioxins), metals or for total organic compounds (TOC). Odour control is limited on recommendations of good practices for the waste receiving areas and storage, generally on the air management systems. In Italy there is an increasingly number of requests, to environmental inspection authorities, Agenzia Regionale per la Protezione Ambientale (ARPA), Regional Environment Agency, to quantitatively describe possible odour annoyance effects from different industrial plants, including MSW incineration plants. Recently ARPA Piemonte has been asked to perform one odour survey for the newly incinerator for the city of Torino, that burns 500,000 t/y of MSW recovering energy through cogeneration. The plant is equipped with a pollutant's automated measuring system (AMS) to assess the compliance with the emission limit values, but not to measure odour emissions. For this reason, it is necessary to assess odour emissions as well, in order to prepare an exhaustive environmental odour scenario for the whole area. We recently presented a risk assessment approach, to evaluate non-carcinogenic and carcinogenic compounds for different sample types, based on STEL or TWA data, or EPA slope factors values respectively. It has been decide to follow this approach to define potential sample toxicity (PT), using the different risk occupational scenarios proposed, before odour concentration analysis of stack emissions samples. Using emission limit values that are set in the permit, PT has been defined. Since samples are presented to assessors in an ascending concentration series, workers exposure has been limited to acceptable levels defining the specific minimum dilution value to be used in the ARPA Piemonte olfactometric laboratory standard procedures.

The development of an electronic nose for the continuous monitoring of odour emissions from an industrial plant would represent an important advantage in the field of environmental odour emissions control. For instance, it would allow to characterize odour emissions over time and use these data as real time input (data) for dispersion modelling purposes. This study presents the first results of our research for the development of an electronic nose designed specifically for emission monitoring. The electronic nose EOS 507 was developed in collaboration with Sacmi s.c. and Progress S.r.l. The emission chosen to test the electronic nose performances was a chimney for the emissions of the fumes produced by a plant for the disposal and treatment of hospital waste. A preliminary study was conducted in order to evaluate the instrument capability to quantify the odour concentration of pure compounds as well as of mixtures emitted by the monitored plant. An accurate instrument training was carried out in order to account for both the different operation phases of the plant and the variability of the conferred waste. The monitoring in the field involved the periodical collection of samples at the monitored emissions and their analysis by dynamic olfactometry, in order to verify the correctness of the electronic nose estimations. The first results obtained seem to highlight that the electronic nose, if opportunely trained, is capable of estimating the odour concentration of the emission at a satisfying level of accuracy.

For odour impact assessment purposes it may be very useful to dispose of an instrument (electronic nose) capable of both qualifying and quantifying odours in ambient air. For this reason, in the last decade, at the Politecnico di Milano, in collaboration with Sacmi s.c. and Progress S.r.l., specific electronic noses for the continuous monitoring of environmental odours were developed. Since the first instrument developed (EOS 835), during the last years an innovative electronic nose was realized (EOS 507) with the aim of guaranteeing better performances on field. This paper reports the results of laboratory tests performed on different pure compounds, selected among compounds that are typical of environmental odour emissions, proving the capability of the new instrument EOS 507 of discriminating odours and to determine their concentrations up to very low odour concentration values (about 30ouE/m3). Moreover, the two instruments (EOS 507 and EOS 835) were used on field, in order to verify their performances with real environmental odours.

The study reported in this paper examined occupational exposure to potential toxic compounds (PTC) for employees working in dynamic olfactometry, following EN 13725:2003 standard procedures. Potential exposure pathways is limited to inhalation of chemicals in air, through the olfactometer, and for this study it was assumed that no chemical transformations or abatements are induced during the dilution steps or by the different sample lines components. Since the possibility of the dilution apparatus malfunctioning cannot be detected in real time, the exposure scenario assessment was based on an upper bound estimate of exposure, using published values of PTC present in emissions of different activities. The non-carcinogenic toxicity assessment was based on short term, acute toxicity effects, while for carcinogenic effects, EPA slope factors were used. The dose was based on individual PTC maximum concentration observed multiplied by the forced inspiratory nasal volumes and corrected by the average number of sample presentations. Different risk scenarios have been calculated for different sample type, both for carcinogenic and non-carcinogenic PTC. Since samples are presented to assessors in an ascending concentration series, i.e. with a lower and lower dilution factor, assessors' exposure is limited to acceptable levels by defining a minimum dilution value, based on specific sample type potential risk, as a guideline for the olfactometric laboratory standard procedures.

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