Air pollution in Jerusalem and the Dan region was 100 times less on Yom Kippur than on ordinary days, when cars are on the roads, air pollution monitors from the Environmental Protection Ministry found.

According to the figures released by the ministry Sunday, levels of nitrogen oxide in the Dan region over Yom Kippur were two to 12 parts per billion - but when the holiday was over, the figure rose to 205 parts per billion. In Jerusalem, the numbers declined from 250 parts per billion in the afternoon before Yom Kippur to between two and 12 parts per billion during the holiday.

Nitrogen oxide is the compound emitted by vehicle exhaust pipes and is one of the prime urban pollution indicators. One component of this kind of pollution, nitrogen monoxide, is considered particularly dangerous to health, causing chronic and even fatal respiratory conditions.

Last week, the Environmental Protection Ministry released figures for 2006, which indicated that some areas of the country exceeded World Health Organization pollution standards for ozone in the lower atmosphere. One of the causes of ozone pollution is the release of nitrogen oxide into the atmosphere.