13 ii. Effects of pollution on health 49. The Government acknowledges that lignite mining causes pollution but denies that the DEH's activities have had any particular effect on the health of the inhabitants of the regions concerned. It makes the general point that there is still uncertainty about the exact effects of pollution on health and on the methods of prevention. For example, there is still considerable disagreement about the long-term effects of particulate, particularly very-fine particulate, pollution on health and what constitute appropriate limit values, which are the subject of Community research under the CLEAR (Cluster of European Air Quality Research) programme launched in 2002. 50. Moreover, the Government highlights the methodological difficulties associated with epidemiological studies arising from the need to work with large population samples, which is complicated by the level of mobility of Greek workers and the fact that certain diseases have multiple causes. One example is cancer, whose prevalence in certain regions is also attributable to poor life styles, particularly the high level of smoking in Greece, and the effects of the Chernobyl accident. It also refers to the difficulty of establishing scientifically a cause-effect relationship between the findings of such studies in terms of morbidity and mortality and environmental factors. 51. The Government acknowledges that lignite mining causes pollution but denies that the DEH's activities have had any particular effect on the health of the inhabitants of the regions concerned. In support of these claims, the Government states that two studies in the 1990s failed to reveal any pollution effects on mortality and morbidity rates in the populations concerned. These concerned an epidemiological study directed by Professor Kondakis of the hygiene laboratory of Patras University School of Medicine on the potential impact of Megalopolis energy activities on the health of the region's population1 and, in the Ptolemaida region, epidemiological research on health problems of the Kozani Prefecture population, conducted by the hygiene laboratory of Thessaloniki University School of Medicine under Professor V. Koutsogiannopoulos2. Similarly, it has not been possible to draw any conclusions on the prevalence of cancer from the first initial findings of the epidemiological study currently being conducted in Megalopolis by the Greek health and safety institute. iii. Acts and omissions of the state 52. The Government states that it has fully complied with its obligations under Article 11 of the Charter and that the environmental consequences of lignite mining and of lignite-fired electricity generation have been properly taken into account. It maintains that steps have been taken constantly to steadily improve the situation. 1 Prof. X. Kondakis, Laboratory of Hygiene and Epidemiology, Medical School of Patras University, Study of the effect of air pollution on the health of inhabitants of Komanos, Kozani prefecture, Patras 1990. 2 Prof. B. Katsougiannopoulos et al, 1st Macedonian Environmental Conference, Thessaloniki, “Environmental Conditions and Health within the Country of Kozani”, 2002.