To prevent infection (such as cold or flu) from manifesting in the lungs and throat it could be helpful to 
do a breathing steam.
Breathing Steam with Fresh Herbs:
Add 1 handful of Fresh or dried Mint or Eucalyptus Leaves to 2 cups of water and bring to a boil. Cook 5 minutes. Place the pan on a cutting board and bring it to the table. You can lean over the pan and breath in the aroma to help open the sinuses.
Breathing Steam with Essential Oils:
Pour 2 cups boiled water into a tea mug or bowl. Add one drop of essential oil of Mint or Eucalyptus into the steaming water. (Do not add the essential oil to boiling water that is on the stove top and do not inhail steam from boiling water.)
Sit down near the tea mug and approach the steam little by little to smell the aroma. If you feel comfortable, you can sit above the mixture while inhaling the aroma for several minutes. If the mixture feels too weak, you can add one or two more drops of essential oil to the hot water.
Caution: Do not use essential oils directly on the skin to avoid irritation of skin and mucus membranes.
Be extra careful not to inhale hot steam with oregano oil over the stove top! You can burn the lining of your larynx, exactly like I did and become very ill, lose your voice and maybe worse. Take the pot away from the stove and never inhale steam from boiling water.
essential oils are Not universal
what one person likes
could make another person very sick
oregeno oil is very potent and strong smelling
although nice as a small does in an italian dish
used as a disinfectant in the home or in steam
it could make someone else sick or unhappy because they do not like the smell
all aromas go straight to the brain
so do not use them when others are unwillingly exposed to them
read carefully
there are florals which are more universal and not minded by most people and very safe
Enjoyed reading through this, very good stuff, regards.