Background Air pollution is the environmental problem that most directly affects urban populations. The most significant sources of pollution are industrial works, power plants, heating and the ever-increasing urban traffic. The most important components of harmful air-polluting substances are on the increase in the course of these activities and as a result of secondary processes they include sulphur dioxide, nitrogen oxides, heavy metals, polycyclic aromatic hydrocarbons, ozone, and floating particulate materials. The current situation regarding air pollution in Hungarian cities may be calculated from the emission measurements made by the Environmental Protection Inspectorates and the data recorded by the emission measurement stations. These data, however, are only relevant for specific parts of the cities. For the coverage of the entire area of cities, a number of expensive measurement stations with high maintenance costs would be necessary which even Western European countries cannot afford. It must also be noted that the mere figures derived from instrumental measurements are not specifically meaningful for the general public, who do not necessarily have an insight from these data into the harmful effects that these pollutants may have on humans, animals, plants and properties. In connection with Hungary’s accession to the European Union, various expectations and requirements will arise which the country will have to meet in different areas, such as environmental protection, to mention just one. One of the expectations of the EU is the application of Framework Directive 96/62/EC on air quality, and that implies the perfection and expansion of the air quality monitoring system Objectives The aim of the project was to establish a bio-monitoring network that – operating in the five most significant towns in the Eastern frontier zone of Hungary – would allow a modern approach to the assessment of air pollution. The network, by informing the national and decision makers of the local governments, would help in the middle and long term improvement of the air quality of the region. In addition the project would aim at raising awareness of the public by using bio-indicators i.e. plants sensitive to air pollution and also making the harmful effects visible for the public. The leaves of the plants selected for the project would become partially grey at a certain level of pollution. Next to each monitoring site, a signboard would be located, explaining in brief the project and how to recognize the pollution. In that way the project would draw the attention of people to the fact that they can do something to reduce air pollution. Results Decision makers: Because of the deficiencies of the air pollution monitoring network operated by the local authorities, the decision makers had limited information on the air pollution. The East Hungarian Biomonitoring Network - EHBN - is the first system which was able to provide large quantitive, conceivable data for the municipalities. Hundreds of air pollution maps have been sent to the cities. The EHBN drew the attention to the fact that lead had not disappeared from the ait in spite of ten years after the phasing out of leaded petrol. This means that the elimination of the pollution source does not mean automatically the eventual elimination of the pollution. Renewal of the car pool alone will never solve the air pollution problems of the cities. The tree cadastres have made it possible to evaluate the value of the green area properties of the cities. As result of the EHBN the cities have increased their green areas in areas which according to the EHBN were highly polluted. The citizens: The media have been reporting on the attenuation of the ozone layer for decades so people are aware of the importance of the ozone in the atmosphere. Nevertheless prior to the project nobody had spoken about the differences between the "good" stratospheric and the "bad" tropospheric ozone. Furthermore the high ozone content of the troposphere has been considered to be the mark of good quality, healthy air. Thanks to the EHBN project it became generally known that the high concentration of the tropospheric ozone is highly dangerous. The other stereotype was that the air pollution was the problem of the central region of the cities. The mapping of the pollutants proved that some of them, especially the ozone, could be more problematic in the suburbs than in the centre. The results of the EHBN have proved that the differences between the highly industrialised Miskolc and the small less industrialised Békéscsaba are smaller than some suggested, because the main reason of the air pollution is the traffic and not the industry in the region. Consequently by preferring public transport to cars the people can actively take part in the reduction of the air pollution. The impact of the project on public awareness was however not quantified. . According to a report carried out by the LIFE external monitoring team in 2005, as a direct result of this project, the 5 participating cities have increased their green areas in sites, which according to the East Hungarian Biomonitoring Network (EHBN) were “highly polluted’. The project officially closed in January 2005. But, the beneficiary says its dissemination work will continue. The longer-term goal is to see the success achieved developing into lasting change in Hungary. See the project website at: http://www.tikofe.hu/