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Introduction

The Veneto Region air quality monitoring network optimization project has been planned by the Veneto Region Environmental Protection Agency (ARPAV) and is financed by the Regional Authority. It involves the main urban areas of the regional territory equipped with a urban air quality monitoring network, including the City of Venice-Mestre.

This project is aimed at responding to new demands on urban and extra-urban monitoring stations optimization, through a macro-scale and micro-scale location revision, spatial covering and reconsideration of the list of monitored pollutants, as provided for by the EU Directives on air quality and the Exchange of Information Directive. Another methodological reference are the European Environmental Agency’s “Criteria for EUROAIRNET” guidelines (February 1999), where the implementation principles for the Air Quality Surveying European Network (EURO-AIR-NET) are enunciated.

The Veneto Region Project on air quality monitoring network optimization should furthermore allow for an amendment of the management costs, with a consequent improvement in the service quality.

The followed methodology for preliminary knowledge research for the project drafting has been characterized as follows:

- existing network situation check;

- regional territory characterization as for pressure and vulnerability;

- new network configuration proposal: determination of the deliverable services, their costs and some representativity indicators for the new network.

Regional air quality network: present situation

The present regional air quality monitoring network situation is based on the principles of the National Decree 20.05.1991 (“Air quality data collection criteria”), which has given the guidelines for the definition of an urban air quality monitoring network, by means of primary and secondary pollutants identification and classification of the number and type of stations where these measurements have to be carried out.

The stations classification, as for spatial location was the following:

- background or reference station (A type), where all primary and secondary pollutants and basic meteorological parameters are measured, as well as PM₁₀, benzene and benzo(a)pyrene to be evaluated by means of manual analytical methodologies. Such stations have to be preferably located in areas not directly affected by urban emission sources (parks, pedestrian areas, etc.);

- high density residential areas located station (B type), where some primary and secondary pollutants are measured, with particular reference to NO₂, HC, SO₂, PM with Pb content and mass characterization;

- high traffic areas located station (C type), with reference to car vehicle pollutants (CO, VOC), on high exposure risk areas like high traffic and low ventilated roads. In this case, the concentration values are characterized by a representativity limited to the immediate surroundings close to the sampling point;

- suburban areas located station (D type) for the photochemical pollutant measurements (NO₂, O₃, PAN), especially during summer periods.

Meteorological data have to be collected too.

The number of stations of the various types indicated depends on residential density, residential settlement structures, different emission sources presence, meteorological conditions, geographic extension and inhabitants number. As a general criterion, three classes of urban centres linked to the inhabitants number, corresponding to the minimum number of monitoring stations were identified:

In 1999 a regional air quality monitoring network study was carried out. Metadata have been collected (station type, geographic coordinates, zone type, etc.) and all regional stations micro-location verified. Main problems regarding the management of regional air quality network are:

- difficulty in sampling methods harmonization;

- excessive presence of urban centres measuring sites;

- costs to manage an huge number of stations;

- stations’ micro-location problems (limited representativity and non conformity with EU Directives);

- overall lack of coverage of the regional territory;

- sampling redundancy of some pollutants (SO₂, TSP) and lack of some others (PM₁₀, benzene, O₃).

The Veneto Region air quality network is presently formed by 60 stations, 31 traffic stations and 29 background stations. Figure 1 illustrates the stations location in the region: some areas are completely “uncovered” (alpine belt, pre-alpine belt, Garda Lake and Eastern Veneto areas), while others, like Mestre, Padua, Verona and Vicenza urban areas show an excessive number of sampling sites.

Venice urban area monitoring network

The monitoring network of the provincial Venetian territory presents a relevant number of stations, the majority of which are located in the City of Venice-Mestre territory (<500.000 inhabitants). During 1999 the City of Venice urban network and the Province of Venice provincial network were transferred under the Venice Provincial Department of the Veneto Region Environmental Protection and Prevention Agency (ARPAV) management. The present monitoring network structure follows the indications of DM 20.05.1991 (”Air quality data collection criteria”). In its configuration the ARPAV managed network is composed of 15 stable stations and 2 mobile laboratories (see Figure 2). The stations are classified according to the territorial range: urban stations and suburban belt stations.

Ten ARPAV stable stations used for atmospheric pollution sampling are located in Venice – Mestre – Marghera urban area; the rest of them are located in Mira, Mirano, Spinea, Chioggia, Martellago e San Donà di Piave municipalities.

The City of Venice atmospheric pollution control network stations managed by ARPAV are classified as follows:

- 2 A type stations: the Parco Bissuola station is located in a Mestre green area; the Via Bottenigo station is located in an area of Marghera not directly affected by significant emission sources and is equipped for industrial pollution sampling;

- 3 B type stations: for densely populated areas (Venice: Sacca Fisola; Mestre: viale San Marco; via A. Da Mestre);

- 3 C type stations: stations for car traffic pollution located along high traffic roads (Mestre: Corso del Popolo, via Circonvallazione; Marghera: via Fratelli Bandiera);

- 1 D type station, for photochemical and secondary pollutants sampling (Maerne di Martellago).

There is, moreover:

- 1 industrial pollution station (Malcontenta, defined as I type).

The stable network is integrated by 2 mobile laboratories, used for point sampling research decided by ARPAV, or required by Local Authorities, Associations, etc., for the local situation pollution control that do not need a fixed station installation.

All data go to the ARPAV Monitoring Network Office, equipped with an electronic management and elaboration database, formed by peripheral units managed by a central unit, with a special software able to simplify validation and check operations of data coming from air quality monitoring stations and mobile laboratories.

The evaluation of the network updating according to the requirements of the regional optimization project is presently under way.

Regional territory characterization in terms of pressures and vulnerability

To carry out the formulation of a monitoring network optimal hypothesis we have been through a serious regional territory study. In particular the territory has been characterized from the pressures and vulnerability point of view (see Figure 3).

The main receptors of bad air quality are:

- population (see Figure 4);

- protected areas, the ecosystems and agriculture (see Figure 5);

- artistic heritage.

The Veneto Region is characterized by diffuse urbanization, distributed over the central part of the territory. The population living in the large urban centres with more than 200,000 inhabitants is a little more than 15%, while about 40% of the total population lives in centres with less than 10,000 inhabitants. It is really important, according to European legislation and European Environment Agency, that all monitoring stations are located so as to be representative of the entire population distribution.

In the present network configuration, on the contrary, the urban centres are over-monitored to the detriment of the population residing in other areas. The other important thing is the choice of measurement sites for protected areas and agriculture. Figure 5 shows the regional typical agriculture (vineyards, wheat and corn cultivation) together with the main protected areas description (regional and national parks, special protection areas).

To determine also these receptors’ exposure, it is necessary to have a number of background stations, besides those already existing, that are not located on representative spots. The most sensitive areas are actually devoid of monitoring stations, in spite of the elevated number of measurement sites. For example the Belluno area, rich in parks and particularly interesting mountainous areas (alpine lakes, moss and lichen vegetation) has only three stations, all located along significantly trafficked roads and therefore not right to determine secondary pollutants like ozone. Similarly the Polesine area and the Veneto Lagoon, two important ecosystems, are under-monitored.

Some kinds of cultivations (vineyards, wheat) and vegetation are ozone-sensitive a secondary and omnipresent pollutant, which is particular because it remains in the atmosphere and is propagated by winds and weather conditions also to areas very far from the polluting source. Following these considerations and the collected information, there are actually regional territory areas (pre-alps belt, Polesine, central area close to the Euganei and Berici Hills), where ozone accumulation is very likely.

These areas should be monitored with particular attention to ozone. The other receptor, continuously exposed to deterioration caused by atmospheric corrosive elements, is the architectural and artistic heritage (monuments, palaces, villas, churches, etc.).

Regional network new configuration proposal

The study has led to the drafting of a proposal on the Veneto Region air quality control network configuration, aimed to reach the described objectives (ecosystem, population and artistic heritage protection).

It has been based on the previous identification of vulnerable and background sites. Other informative elements have been derived from the Regional Air Quality Plan and from the structural funds of the EC Regulation n. 1260/1999.

Such configuration should be formed by 40 stations, where 7 are “Hot spot” stations, located on the main metropolitan areas and medium/small size representative centres, 30 are “Background” stations (18 classified as “Urban” and “Suburban” and 12 classified as “Rural near-city background"), and 3 are “Industrial” stations (classified as suburban areas). To these 40 stations, 10 mobile laboratories should anyway be added. These to be dedicated to systematic and regular monitoring all over the territory which is not covered by stable stations: the existing stations that will be kept are red , the new ones are blue, the stations belonging to the former EMEP-RIDEP network planned to be kept in the new configuration are light-blue (see Figure 6).

The suggested configuration, is the necessary and suitable stations’ network able to describe the local and regional atmospheric pollution dynamics, as provided for by National and European legislation. It should be subjected to Provincial and Municipal Authorities evaluation.

Apart from the rise in management and maintenance costs, there is nothing preventing the improvement of the number of measurement points if the Local Authorities should propose and support it.

Acknowledgements

Most of the text has been kindly made available from ARPAV - Regional Air Observatory (authors: Erika Baraldo, Alessandro Benassi, Francesca Liguori, Ketty Lorenzet, Giovanna Marson, Paulo Tieppo).

Last Updated

13th January 2005