**2. A Historical Perspective**

Throughout history and across different parts of the world, malodors have varied in intensity and cultural impact as has the use of perfumes to mitigate malodors. Influenced by the Egyptians, the ancient Romans used perfumes intensely and even applied them to domestic animals to mitigate malodors. In the 4th century, the use of perfumes and pleasant aromas was condemned as an indulgence and idolatry by the Christian church [11]. Partially as a result of this policy, the European cities of the medieval and renaissance ages are known to be among the most foul-smelling environments in human history. Without proper sanitation infrastructures, their close quarters and high population density led to high concentrations of malodors [12]. Rotten food, excrement and slaughtered animal remains frequently littered the streets [11]. To mitigate indoor malodors, Medieval Europeans scattered herbs throughout their homes, sewed aromatic leaves into pillows, or polished wood with myrrh. To perfume themselves, they sprinkled rose water on their clothes or wore pomanders.

Out of this environment emerged the beginnings of modern commercial perfumes. Perfumes with essential oils were made for royalty by Italian chemists in the 14th century. With Caterina de' Medici's marriage to Henry II in the mid-16th century, Renaissance Italy's perfumes traveled to France where they continued to flourish centuries later. Throughout these periods, fragrances were used to mitigate the negative impact caused by malodors and functioned as a social symbol of higher class [12]. Perspectives on odors have changed significantly since the Renaissance, though people today still seek out means of combating malodors and asserting control over unpleasant smells in their lives, often through the use of pleasantly scented products like air fresheners.
