In general, nasal mucus is clear and thin, serving to filter air during inhalation. During times of infection, mucus can change color to yellow or green either as a result of trapped bacteria or due to the body's reaction to viral infection.
As such, there is to be no work done on this day. There are other restrictions, as well. Unless health dictates otherwise, Yom Kippur is observed by a 25-hour fast that begins prior to sunset on the evening before Yom Kippur and ends shortly after nightfall on the day of Yom Kippur. During this time, you are not allowed to consume any food or beverage, including water.
Yom Kippur 2017 begins at sunset on Friday, September 29 and ends at sundown on Saturday, September 30. Click here for more questions and answers about Yom Kippur. Yom Kippur is the Jewish day of communal and personal atonement for sins committed during the past year. Fasting is one of the central components of the Yom Kippur holiday. Jewish adults are commanded to fast, but there are exceptions for pregnant women, nursing mothers, and those who are ill. Click here to see who is traditionally commanded to fast, and click here for tips on staying healthy during the Yom Kippur fast.