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General features and application fields

Passive samplers are ideal for air monitoring programs, personal, outdoors and indoors. Passive sampling devices can monitor air pollutants without the need for electricity, data loggers or pumps. Passive sampling devices are simple to operate, portable and represent a cost-effective solution for monitoring air quality at locations where continuous monitoring is not feasible. Attalea is the exclusive reseller of passive samplers of the well known Swiss company Passam, among the leading company in this field worldwide. Passive sampling involves the exposure of a reactive surface to the air, and transfer of the pollutant occurs by diffusion from the air to the surface. The surface consists of a solid chemical compound or a filter that is impregnated with a reactive solution. Samplers are typically exposed for predetermined periods 1week to one month). Samplers for short-term measurements are also available.

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Analysis are carried out at Passam certified laboratory (ISO/IEC 17025 /EN 4500). Sulphur dioxide, nitrogen dioxide, ozone, hydrogen sulphide and volatile organic compounds are common pollutants monitored using passive samplers. The sampling technique is based on molecular diffusion of gases. The gas molecules diffuse into the sampler where they are quantitatively collected, which gives a concentration value integrated over timeThe sampling process begins by opening the sampler.

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Sampling is carried out over a period events that last for a short time period, such as one hour, may be "averaged out". Nonetheless this approach can highlight critical environmental conditions where a more detailed analysis is required. A major advantage of using a passive sampling system is that a network of multiple samplers can be used over a large area to determine pollution levels and their spatial/temporal variation of pollutant levels.

Passive samplers are also useful for looking at long-term trends of air pollutants at specific locations. However, since sampling is conducted over a period of about one month, events that last for a short time period, such as one hour, may be "averaged out".

Epidemiological investigations

Air pollutant measurements of in outdoor, indoor, or personal air is critical for assessing exposure to air pollution and potential health effects. Passive sampler is becoming more and more an interesting approach in exposure and health effects studies, given its simplicity and low cost. Also, many passive samplers are capable of providing excellent performances in terms of sensitivity and reproducibility.

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Passive samplers are appreciated as they are simple to operate and provide cost-effective information on air quality. .Passam passive samplers are used worldwide. In Italy thsese devices were adopted for detailed investigations regarding air quality in major urban areas as Milan, Monza, Sondrio.

Environmental Impact Assessment

Measurements of average concentration levels of air pollutants are carried out as part of baseline environmental impact assessment studies. A comparison between the measured concentrations and the applicable air quality standards can provide the required documentation for the development of future scenarios. In Italy Passam samplers were used in the framework of EIA regarding power plants, airports and other industrial facilities.

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Forest ecosystems

The earliest studies of the effect of air pollution on forests were conducted around industrial sources of pollution and showed pollution levels were severe enough to severely damage vegetation in the vicinity. This kind of pollution is unlikely to be met in Europe, but some pollutants still represent a major threat. This is the case for ozone which causes direct injuries and indirectly reduces tree resistance to other stressors. Passive samplers are widely use in Europe to assess ozone pollution in forest areas and have provided first hand data regarding air quality in remote regions. Passive sampler data can be used to assess exposition over predefined time periods (e.g. AOT40).

Cultural heritage

Air pollution can threaten heritage materials from museums, galleries, libraries and archives. Deterioration is usually slow and progressive: prolonged exposure can cause severe damages to a wide range of materials and manufacts. The number of sites to be monitored depends on the aims of the survey and the size of the building. The logistics and cost of environmental monitoring can represent challenges for heritage managers because of the relevant number of environmental parameters to consider. Air pollution assessment and monitoring should be for the pollutants considered to be the greatest hazards at these locations. In the case of externally generated pollutants this should include at least two, preferably three, external sites. Inside the building, the monitoring sites should include corridors and entrance halls as well as the collections space, to assess the pollution spatial distribution. Passam passive samplers were used to preliminary assess air quality in several Italian museums. Among the monitored structures the following should be mentioned: Musei capitolini di Roma, Palazzo reale di Genova, Pinacoteca nazionale di Bologna, Museo regionale di Messina, PAC di Milano, Museo archeologico nazionale di Napoli, Museo di archeologia di Padova, Galleria nazionale Palazzo Abatellis di Palermo, Istituto per la storia del risorgimento italiano di Roma, Fondazione Sandretto Re Rebadeungo di Torino, Palazzo ducale di Urbino. Multi-pollutant investigations were performed at the Loggia di Michellozzo, in Florence (see picture)

Agriculture and livestock farming

Air pollution can cause relevant injuries to commercial agricultural crops and yields. In India air pollution has become so severe that yields of crops are being cut by almost half, scientists have found. Researchers analysed yields for wheat and rice alongside pollution data, and concluded significant decreases in yield could be attributed to two air pollutants, black carbon and ground level ozone. The finding has implications for global food security as India is a major rice exporter. Measurements of air pollution can provide relevant information regarding areas at risk

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Livestock farming represent the major source of ammonia and hydrogen sulphide. The first contributes to acidification of soils and water. Ammonia represents an important threat as it is widely distributed over the European agricultural areas (left).. Measurements with passive samplers may provide useful information regarding odour annoyance due to ammonia and H2S presence in ambient air.

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Indoor measurements (homes, schools, workplaces)

Passive samplers, are used for indoor air pollution measurements. Passive sampling has several potential advantages over other methods, including lower cost, small size, and less disruption to building occupants. Often passive samplers are used to screen a building, and if a problem is indicated, other methods are applied to investigate more in detail its relevance.

Validation of dispersion models

Comparing modelling results with known concentrations values that have been measured, contributes to improve their quality and credibility. Input data such as emission factors, meteorological data as well as topographic conditions are often inaccurate, justifying the improvement of the modelled concentration field by adjusting the input.

Mapping

AOT

Passive samplers may represent a valuable source to map air pollution concentrations and to display spatial and temporal fluctuations of pollution load. A specific mapping procedure to map accumulated ozone concentrations over the 40 ppb threshold (AOT40) is presented in the Manual section. One example of the mapping result is reported below.

Personal exposition

Personal passive air samplers (or badges) have been used extensively for industrial hygiene and related occupational exposure purposes Although a long sampling time is usually required for passive samplers to detect ambient air pollutants, they are an attractive method for monitoring personal exposure. Several epidemiological studies have demonstrated that the development of passive samplers for personal exposition monitoring is feasible.

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Attalea s.n.c. di G. Poggi & C. Sede legale: Via Pergolesi 2 I-20124 Milano Uffici/offices: Via Pordenone 19 I-20131 Milano
Tel/Phone +39 02 450.71.289 Fax 02 450.70.289 mail info@attalea.net P.IVA 13392550151

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