The Alcohol Sniff Test

The Alcohol Sniff Test abbreviated (AST) was developed at the UCSD Nasal Dysfunction Clinic. It is a simple, reliable, highly accurate means for measuring olfaction. While it is possible to administer the AST to oneself, it is better to have a friend administer the test.

The test was first developed and validated at the UCSD Nasal Dysfunction Clinic. It has been reported in the Archives of Otolaryngology.

The test is normally administered with a disposable 70% isopropyl alcohol disposable pad. These are the alcohol swabs typically used in hospitals and doctors' offices and are readily available in many pharmacies. Tear the top of the disposable container away from the pad so that 1/2 - 1/3 of the pad is exposed. Ask the patient to take a sniff so that they can identify and recognize the alcohol odor. Pull the pad away from the patient, ask them to close their eyes. Place the pad directly under the nose at approximately mid chest. Ask the patient to breathe normally. If they breathe deeply or if they sniff, the test is not valid. When the patient is breathing normally, move the pad toward their nose 1-cm with every exhalation. Ask the patient to indicate when they first smell or detect the alcohol odor. Measure the distance from the bottom of the nose to where the patient first detects the alcohol. Normals should detect the alcohol odor at 20 or more centimeters. Those with a diminished sense of smell, called hyposmia, will detect it between 2 cm and 20 cm. Those who are truly anosmic will not smell the odor. They may sense or feel the alcohol when it is very close to their nose. Some will confuse this with smell, some will say, "I can feel it, but not smell it."

In the original study the same test was repeated five times. In most cases the results are very clear and one or two times is more than adequate.

For those not familiar with the metric system, 1 cm is approximately 4/10 or 3/8 of an inch.

When used as a screening tool many move the alcohol pads towards the nose at a rate much faster than 1 cm with each exhalation. In such cases normals will detect the pad at less than two finger-breaths below the chin. Anosmics will not detect the pad until it is above the upper lip and immediately beneath the base of the nose. Those with an intermediate result i.e., from above the upper lip to two finger-breaths below the chin, are considered hyposmic.

Figure 1. The Alcohol Sniff Test shows the test performed on a patient at the UCSD Nasal Dysfunction Clinic. (For those with a slow modem be sure to check the file size before clicking on the down modem icon.)

The figure shows six separate pictures. Starting in the upper left and progressing to the right, the first picture shows a patient and a 70% isopropyl alcohol wipe. The second picture shows the alcohol wipe being opened. The third picture shows taking a short sniff to identify the smell of the isopropyl alcohol. In the fourth picture (bottom left) the test is being administered. The patient has her eyes closed. She is breathing normally and the alcohol pad is moved slowly from her lower chest upward toward her nose. The next figure shows the alcohol pad progressing nasally. The last picture shows that the patient has smelled the alcohol. This is above the chin. This patient is probably hyposmic.