Air quality improved in the Dan region, Haifa, Beit Shemesh and the Krayot in 2007, but deteriorated in Jerusalem and Modi'in, according to an Environmental Protection Ministry report released over the weekend. In most cities, there were fewer days of high or very high pollution in 2007 than in 2006. But there were slightly more days of high pollution in Jerusalem and Modi'in. In the Dan region, there were 45 days of high to very high pollution in 2007 as opposed to 59 in 2006. In Haifa, there were seven as opposed to 15; the Krayot registered 12 as opposed to 17; Afula dropped to seven from 13; while the number of high pollution days in Beit Shemesh dropped by almost half from 12 in 2007 to 22 in 2006. Rehovot saw 10 days as opposed to 15. However, there were higher rates of ozone, which could lead to cancerous tumors, strokes and high blood pressure, in Afula, the Dan Region, in Modi'in, Karmei Yosef, Gdera, and Gush Etzion. Ozone rates dropped in Beit Shemesh, Kiryat Malachi, Sderot and Eilat. The improved air quality in the Dan region was the result of fewer sources of polluting emissions, as well as salutary weather conditions which dispersed the pollution more rapidly, the report said. In Jerusalem and Modi'in, large building projects damaged air quality. The difference in Jerusalem was slight: 33 days of high to very high pollution in 2007 as opposed to 32 in 2006. The light rail project, which has ripped up much of downtown, contributed to the poor air quality, according to the report. In Modi'in, building projects caused a jump from 18 days in 2006 to 22 days in 2007. Air quality stayed constant in Beersheba and Carmiel. Beersheba stayed steady at 12 days and Carmiel at 9. The ministry noted it had been fighting air pollution in many ways. Among its actions, the ministry said it had tightened the emissions levels for diesel vehicles in February 2007 for models from 2001 and up, and that new diesel vehicles were required, as of October 2006, to adhere to the EURO4 standard which also demanded reduced emissions levels. Reducing vehicular emissions brought down the level of ozone, according to the report. The ministry also pointed to more spot checks on factories and the implementation of pollution reducing technology at factories with high emissions.