1. The Parsi Gujarati word Naso, derived from Avesta word nasu, means any dead, decomposing, putrefying matter emanating from or being a part of a human being. After death, the entire human body begins to decompose, and in Zoroastrian religion it is considered the biggest naso which is to be properly and ritually disposed. It is further stated that a demon of putrefaction called the ‘Druj-e-nasu’ attacks naso. Men have to keep away from and safeguard themselves from naso as far as possible.

2. The term naso is applied to dead, decomposing, putrefying matter emanating only from humans, since humans are conscious beings who do good and fight evil. Since dogs also intuitively fight evil, druj-e-nasu even attacks dogs after death. From this view point the putrefaction that arises out of animals (except dogs) or plants cannot be considered naso.

3.The text of the Vendidad is chiefly about laws to deal with impurities arising out of Naso. It has elaborate injunctions to safeguard mankind from the harms arising out of the attack of druj-e-nasu on the corpse.  The Patet Pashemani prayer mentions repentance for one who has come in contact with different types of naso.

4. In Zoroastrian after death rituals, in order that the naso is fortified, contained and does not spread, a kash that is “a furrow” is made around the corpse with iron nails along with chanting of prayers. Fire is to be kept burning, fragrance has to be kept over it and prayers are to be chanted to limit the ill effects of the naso.
5. In Zoroastrian tradition, the term naso is applied to a dead thing when it is fresh or wet. In Gujarati it is known as ‘lilo naso.’ The term her naso is applied to dried naso, which is known in gujarati as ‘suko naso.’ Only fresh naso is potent. After a few months of drying, the wet naso becomes dry and loses most of its power to putrefy. After a year the naso, if exposed to sunlight, becomes completely dry and loses its physical and hence spiritual power to putrefy.
6. The druj-e-nasu has the tendency to attack the living. Since it always attacks at the centre, all actions dealing with naso arising out of a corpse have to be done in a pair with a ‘paevand’, that is, connection between two persons, whether they are priests, lay men or corpse-bearers. If anybody comes in direct contact with a corpse after the Sachkar, he is said to be ‘riman’, that is, “impure”. Such a man can be made ritually pure by a nahan. Direct defilement from naso is called ‘hamrit’ and indirect defilement is called ‘patrit.’
7. The druj-e-nasu become more active when the corpse is moved. That is why mourners turn away their face when the corpse is lifted in the midst of the Geh-sarna prayer. For the same reason mourners are expected to fortify themselves with baaj prayers and walk in pairs when they follow the corpse during the Paaidast.
8. Any part of human body, once it is severed from the living body, becomes naso. Hair and nail are considered alive as long as they are attached to the body, though they do not constitute living tissues. However, after they are cut they too are considered naso. It is necessary to dispose cut hair and pared nails, properly, and not leave them scattered in the house. In Zoroastrian tradition it is mandatory to take a bath after cutting hair (which includes shaving) and paring nails. This practice is beneficial also from a hygienic view-point.

          9. Dokhmenashini and Khurshed-nagirashni – the mode of disposal of death of                         Zoroastrians has been designed in such a way that the naso emanating from the                     corpse does the least harm to other humans and creations like fire, earth, water,                     animals and plants.