Put a couple of drops on a tissue and sniff it every now and then.
For pro-olbas oil use, put a couple of drops on your finger tip and touch the inside of your nose (probably a bad idea that will melt your nose, but works for me)
Popular alternatives to
Olbas Oil 10ml - Pack of 1
Bio-Oil Skincare Body Oil, Serum for Scars and Stretchmarks, Face and Body Moisturizer Dry Skin, Non-Greasy, Dermatologist Recommended, Non-Comedogenic, For All Skin Types, with Vitamin A, E, 4.2 oz
Heritage Store Rosewater & Glycerin Hydrating Facial Mist, for Dry Combination Skin Care, Rose Water Spray for Face with Vegetable Glycerine, Made Without Dyes or Alcohol, Vegan & Cruelty Free, 8oz