There could be a couple of things going on here. One thing to consider is that a true wool allergy is apparently extremely rare. In some cases, people are not allergic to the wool itself, but the method of processing.
All wool is generally carbonized. This means that it’s been treated to remove impurities such as vegetable matter that was in the sheep’s coat when it was shorn. The chemicals used in this process can include such things as sulfuric acid. After processing, wool for carpets is often treated with a whole host of other chemicals, including stain protection.
But technology is always changing, and some chemicals have been removed from the standard processing of wool due to government and consumer pressures. So, it is possible that your wool carpet was processed in a way that has reduced or eliminated your allergen.
Another thing to consider is that allergies can be very fluid. What I’m allergic to today could be quite different from what I’m allergic to over time. Allergic sensitivity can both increase and decrease over time. As a result, it is possible that you are just not allergic to wool anymore.
Some research indicates there could be a cycle for allergic conditions, and there is anecdotal information that shows some allergies going through a 7-8 year cycle, from initial onset to reduction or elimination of the allergy. Unfortunately, not every person will experience this cycle and some allergies do become a lifelong condition.
A final suggestion is that you are only allergic to wool if you come into direct contact with it. Are you a person who always wears slippers or socks around the house? If so, since the carpet is on the floor, this could be sufficient to protect you from the effects of the carpet.
Of course, this wouldn’t be possible without the concept of allergic threshold. Allergy is not an all-or-nothing response. Sensitization to an allergen takes place over multiple exposures (although it could be as little as two). Depending on the type of allergy and your allergic response, sensitivity will not be a constant.
If you had an extreme sensitivity to wool, as is the case with allergies that result in anaphylaxis, you could react to as little as microscopic amounts of wool allergen. Clearly, if you are living with a wool carpet in your home, your sensitivity is not in the high range! So, it becomes a matter of how much exposure is happening and whether the ongoing exposure is exceeding your personal allergic threshold.
The best analogy for allergic threshold is to think of a rain barrel catching water run off from your eaves. If the barrel is large, then it can contain a large amount of water before it overruns. So, you could have a considerable rainfall, even over a number of days and yet the barrel will not overflow. However, if the barrel is small and there is even a single large downpour, the barrel could overflow immediately.
Your allergic threshold is your bucket; as long as the bucket doesn’t overflow (your exposure is too high), your body is clearing the allergen and you remain symptom free. If the exposure is too high, your body ceases to be able to clear the allergen normally. At this point, your immune system identifies the allergen as a harmful substance and you have an allergic reaction.
This concept can also be affected by other allergies that you have. There is some research that indicates your allergic threshold is affected by your overall exposure to allergens. As a result, you might not have an allergy to cats in the winter months, but be unable to sit in a room with one when your seasonal allergies are acting up. All these factors could be affecting your tendency to have an allergic reaction or not.
