Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions.   Wa alaikum assalam wa rahmatullahi wa barakatuh.   As to what follows:   In response to your question, we say:     Smelling fragrant and good smells is not from the nullifiers of fasting nor does it reduce the reward of the fasting person. This is because fasting is refraining from nullifiers of fasting which Allah specified and explained. Allah the Exalted said, “So now have sexual relations with them and seek that which Allah has ordained for you (offspring), and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night)” [al-Baqarah 2: 187]. This verse contains the basis of the nullifiers of fasting, and there is nothing in the Qur’an or Sunnah which indicates that elephant scents and perfumes which are smelled break fasting. This is a point of consensus among the scholars and there is no difference of opinion among the scholars about this issue. Rather, the scholars  (may Allah have mercy on them) differed about inhaling incense. Incenses differ from fragrant and good scents because incense is smoke which rises and particles are formed from it. That is why a group of scholars have stated that inhaling incense breaks the fast. As for the presence of good scents whether they are the usual scents like burning incense, oil, and oil-based scents, or scents which are used in materials which diffuse good smells, soaps and substances which are used for bathing, the scents which a fasting person can smell in insecticides, pesticides and so on; all these scents do not break fast, and there is no proof that these things break fast, even if the fasting person detects the taste of these things in his mouth; that will not nullify his fast because there is no proof for that. This is why the scholars (may Allah have mercy on them) discussed an issue and said, “If a person steps on something and senses its bitterness in his throat, his fasting is not broken because this is not called eating or drinking.” Thus, there is no proof that these scents break fast. Therefore they remain on the original ruling which is that they are permitted for a fasting person, so it is allowed for him to use these scents whether it is in the early part of the day or at the end of the day, whether these scents are on his body, clothes or the place that he sits. As for incenses; a group of scholars have stated that they are made up of physical particles thus they break fast. A group of scholars held that incenses do not break fast because what goes up from the smoke which emanates from the incense is of a small quantity which does not affect fasting and is not described as eating or drinking.   Similarly smoke from the exhausts of cars, dry cleaners, kitchens, wood and so on does not break fast because it is difficult to avoid it, and it is known that what cannot be avoided does not affect fasting if it reaches the throat. Here is an important rule concerning what is considered to be a nullifier of fasting: everything that cannot be avoided does not break fasting if it reaches the throat. The same applies to aero planes in the air (if there is some substance in them which cannot be avoided and it reaches the throat), moist air which reaches the throat, gas, smoke in the street and so on. All these things are not nullifiers of fasting because they cannot be avoided.