Effect of smoking on the sense of smellFeatured science projectScience project video

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This science fair project was conducted to study the effect of smoking habits on a person's sense of smell. The science project experiment involved the participation of smokers and non-smokers using 10 different types of scents, at 3 different levels of concentration.


Smokers have a diminished ability to distinguish the intensity of scents, compared to non- smokers.


Smoking and smell

The sense of smell is also known as olfaction. It is one of the 5 senses that we have: the others are sight, hearing, touch and taste. Odors from foods, and the scent of flowers or fruit enter our nostrils and are detected by the sensory cells located inside our nasal cavity. These cells will send signals to the brain to recognize and remember the smell.

Smoking habits are known to affect the sensitivity of the nose. People who smoke regularly have been found to be unable to recognize some odors. This condition seems to affect both young and old.

Both the sense of smell and taste are required to appreciate the flavors of the food that we eat. More of its flavor actually comes from smell, instead of its taste. Therefore, people who smoke regularly and who have a diminished ability to smell, will not be able to appreciate good and tasty foods as much as non-smokers are able to!

Scientific Terms

Sense of smell, olfaction, sensory cells, nasal cavity


The materials required for this science fair project:
- Flavors – cinnamon, rose, lemon, lavender, banana, vinegar, apple, orange, soy sauce
- 30 test tubes
- 3 test tube stands
- A blindfold
- 10 participants who are heavy smokers (ascertain that they typically smoke at least 10 cigarettes a day and have been doing so for at least 5 years)
- 10 participants who are non-smokers
- Tap water
- 10 syringes


1. For this science fair project, the independent variable is the concentration of the 10 test scents. The dependent variable is the choice of the most intense scent  selected by the participants. This is determined by asking the participant to smell the 3 samples of each scent in the test tubes. The constants (control variables) are the number of scents used and the amount of scented liquid placed in the test tubes.

2. The liquid scents of cinnamon, rose, lemon, lavender, banana, apple and orange are purchased in small bottles from a department store or supermarket.  Vinegar and soy sauce may be purchased from a grocery store.

3.  Three test tubes  are each  labeled as cinnamon, rose, lemon, lavender, banana, vinegar, apple, orange and soy sauce. The 3 test tubes for each scent are now labeled 1, 2 and 3.

4. Using a different syringe for each flavor, 50ml of the first scent is transferred to test tube labeled 1. 25ml is transferred to test tube labeled 2 and 10 ml is transferred to test tube  3. Another 25ml of water is added to test tubes marked 2 and 40ml water added to test tubes marked 3.

5. The first smoker is blindfolded. The participant is given the 3 test tubes for the 1st flavor and asked to smell and identify which test tube has the strongest smell. After the choice is made, the results are recorded and the same test is done on the remaining 9 flavors.

6.  Procedure 5 is repeated  for the remaining 9 smoking participants. The total number of smoking participants who made the right choice for each flavor is recorded in the table given below.

7. Procedures 5 and 6 are repeated using  10 non-smoking participants and the results are recorded.


It  was observed that the number of correct choices made by non-smokers were higher than those made by smokers, for all the 10 flavors.











Soy sauce
























The chart below represents the result of our science project experiment.

smoking and smell science project


The hypothesis that  smokers  have a diminished ability to distinguish the intensity of scents, as compared to non-smokers, is proven to be true.

The sense of smell is important for us to appreciate the flavors of good food. However, smell can also serve to warn us of danger. For example, the smell of gas from a stove or heater is a sure sign that something is wrong and this helps us prevent damage to and loss of property and lives.

Also consider

What do you think your results would be, if this science project were to be repeated to compare the sensitivity of smell according to the participants’ gender and age?

Alter the science experiment by observing the  participants’ ability to recognize flavors, instead of odors.


Impaired sense of small - http://thescooponsmoking.org/xhtml/effects/impairedSenseOfSmell.php

Why does smoking affect your sense of smell? - http://www.electroniccigarettetavern.com/smoking-effects/why-does-smoking-affect-your-sense-of-smell/

Olfaction - http://en.wikipedia.org/wiki/Olfaction