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Q. We have tenants whose children seem to have allergies. They have pets but feel that replacing all the carpeting in the home will remedy the problem they’re experiencing. We noticed that Stanley Steamer products are AAFA certified about 98% of dog dander and 92% of dust mites. Do you believe that cleaning the carpet is sufficient, or should we replace all of the carpeting in the home in order to be sure it is not causing the allergy problem?

A. This is a challenging question, as there are many variables that may determine the effectiveness of this carpet cleaning in resolving the childrens’ symptoms.

Numerous studies have demonstrated the benefits of strict environmental control in patients with asthma and allergies.  However, other studies have produced conflicting results.  This may be because allergen levels were not reduced enough to benefit the patient.  Another possibility is that the patients studied may have been allergic to more than one thing, and reducing exposure to just one allergen was not sufficient to decrease allergy symptoms.

The type of carpet in the home will impact the results of cleaning.  Different types of carpet are easier to clean than others.  In a study of cat allergen in carpets, the carpets that were easiest to clean were short, low-pile carpets made of high density, low surface area fibers, and coated in fluorocarbon The study did not examine dust mite allergen, but it is likely the type of carpet will also impact the removal of this allergen.

If the children are pet allergic and have a pet, cleaning the carpet will have little effect on the total amount of pet allergen present in the home. Pet allergens are also found in bedding and furniture, are constantly being produced by the pets.

Many patients in the U. S. are allergic to more than one allergen. Even if the carpet cleaning were to remove a large amount of one allergen, the allergy sufferer may not feel relief because carpet cleaning has not impacted their other allergens.

The family should consult the childrens’ allergist for an evaluation, and to discuss management and treatment options.

Q. I am in the market for allergen-proof pillow and mattress covers, but am confused by the various types available. What are the different types of encasings? Do they vary in effectiveness or comfort?

A. There are four basic types of materials commonly used to manufacture allergen-barrier encasings: vinyl, laminates, woven microfiber fabrics, and non-woven microfiber fabrics. Each material type is available in a range of fabric qualities and sewing constructions.

Vinyl encasings are inexpensive and effectively block allergen escape. But because they are stiff and noisy, and do not allow air or water vapor passage, they are uncomfortable to sleep on. They are suitable, however, for encasing a box spring, as a you won't be sleeping directly on the plastic. The vinyl should be sufficiently thick so that it will not tear easily.

Laminate encasings are made by fusing a plastic-type membrane, usually polyurethane, to the bottom surface of a fabric. The membrane acts as an effective allergen barrier. Although less uncomfortable than vinyl, they are generally somewhat stiff, have only very minimal water vapor permeability, and are not air permeable. An additional problem with laminate encasings is that washing and drying may cause the urethane membrane to separate from the fabric, making the encasing unusable.

Woven microfiber fabric encasings are woven from special yarns, each of which is made up of 100-200 ultra-thin filaments. Because the tightly woven microfiber fabric itself acts as a filter that prevents allergen escape, no plastic membrane is needed, and air and water vapor can pass freely through the fabric, making it very comfortable for use. Unfortunately for the consumer, microfiber fabric encasings vary considerably in the tightness of their weave and therefore in their effectiveness as allergen barriers. Some woven microfiber encasings block only certain allergens, while higher quality woven microfiber encasings prevent the passage of all types of allergens. A high quality woven microfiber encasing is the state of the art for comfort and allergen blockage.

Non-woven microfiber fabric encasings are not woven on a loom, but rather are manufactured by fusing a mass of randomly crisscrossing short filaments to each other with heat, glue, and pressure, resulting in an embossed pattern on the surface of the fabric. Although the fabric is inexpensive, it is not washable, and the embossed patterns created by the manufacturing process are deep enough to allow dust mite growth and high levels of allergen accumulation on the surface. These facts suggest that non-woven microfibers do not succeed in reducing allergen exposure, and should not be used for allergen avoidance.

Note that encasings of any fabric type can differ in the quality of their sewing construction. Desirable features include bound seams, no gap at the edges of the zipper, a barrier fabric flap beneath the zipper to prevent the escape of allergen through the zipper webbing, and an extra-long zipper for easier placement of the encasing on a mattress.

Q. A few months back I heard an allergist on television talking about the Ionic air filters being toxic to the lungs. I have had these air filters for a few years in every room, and have Copd caused by allergies. I was wondering where there was a resource of which I could find out more information as to what problems these air filters cause,as I certainly don't need anymore problems with my lungs. I have searched the internet but the only thing it brings up is sales of these air filters, even though I put in toxic lungs etc when searching.

A. These are not really air filters. They are usually advertised as clean air machines or air purifiers. The ionization changes the charge on the particle and it sticks to the next thing it comes into contact with. There is usually not enough air flow to effectively filter many particles, so they provide minimal benefit as air cleaners. The health risk comes from the ozone they produce which is toxic to the nose and lungs. Here is a link to the EPA (Environmental Protection Agency) web site on this: better thing to use is either a HEPA room air cleaner rated with a Clean Air Delivery Rate (CADR) for the size room you are using it is. For central air cleaning a furnace filter with a MERV rating of 11 or 12 will help filter the particles blown through heating and air conditioning system.