By Stephen Farrell
JERUSALEM (Reuters) - As Israel's highways and city centres fell silent on Yom Kippur, environmentalists hailed the holiest day of the Jewish calendar as providing a brief but welcome respite from pollution.
The "Day of Atonement" - a period of fasting and prayer just after the Jewish New Year - is observed by Jews the world over but in Israel the country largely grinds to a halt.
It is a public holiday during which most Israeli Jews refrain from driving during the 25-hour holy period.
The decades-old traditional driving ban is not dictated by law, but observed out of deference for the holy day, which this year began at dusk on Tuesday and ends after dark on Wednesday.
Adults and children take advantage of the deserted highways to ride bicycles, scooters and skateboards without fear of being hit by cars or trams, even in major cities such as Tel Aviv and Jerusalem.
The change in behaviour reduces man-made emissions to the lowest level of the year, say scientists.
"There is a large impact, it is much less pollution than on other days," said Professor Pinhas Alpert of Tel Aviv University's Department of Geophysics.
"On shabbat and other holidays we have reduced amounts but on Yom Kippur it is really, really unique in the whole world that we have very little amounts of pollutants."
He singled out nitrogen oxide emissions in particular, collectively known as NOx, saying they fell "sometimes by a factor of 100" compared with normal days. There were also many fewer polluting particles in the air, he said.
The shutdown is not total. Power plants still operate, and police vehicles and ambulances patrol streets, usually flashing their lights to warn unsuspecting pedestrians.
And in many towns and villages populated by Israel's 21 percent Arab minority, life goes on as it does in East Jerusalem where businesses stay open and cars, buses and motorcycles move around in areas that are not blocked to traffic.
Nobody contends that one day of reduced emissions frees a country from the effects of climate change, however.
"Once the cars start moving again on the night...of the ending of the day of Yom Kippur, it already goes up immediately," Alpert said.
(Reporting by Stephen Farrell; Editing by Mark Heinrich)