Should us care that much about dust mites? It seems that our pillow never make us sick, plus new pillows were expensive.

Dust mites are microscopic creatures, about 0.4 millimeters in length, that feast on flakes of human skin. Their feces contains a substance called DerP1, a very potent allergen. People who are allergic to dust mites may have asthmalike symptoms, eczema or chronic sinus problems.

Most people believe that bed parts, including pillows and mattresses must be replaced regularly in preventing from nasty dustmites. Based on researches, the truth is more than our understanding. People who allergies to dust mites has to actively protect themselves against these creatures.

The question is, would the the rest of us skip the expensive routine of bedding replacing?Problem is not everyone is clear whether we are mite allergic or not. Even if you clear that you are allergic, there still confusion about which strategy really works.

Here are some tips on how to decide if you should be worrying about your bedding and the dust mites that take up residence in them — along with expert advice on the most effective home interventions.

AN ALLERGY TEST Mites proliferate in warm, humid climates. They are almost nonexistent in places like New Mexico but thrive in tropical areas like Florida. Here’s a mite test: “If your home is full of static electricity, you likely do not have mites at the moment,” said Dr. Thomas Platts-Mills, director of the Asthma and Allergic Disease Center at the University of Virginia.

But if the temperature and humidity rise, watch out. About one in four Americans has some type of allergy, and within that group about two-thirds are allergic to dust mites, said Dr. James Sublett, an allergist in Louisville, Ky., who is chairman of the Indoor Allergen Committee of the American College of Allergy, Asthma and Immunology.

“Very few people are allergic to just one thing,” he said.

If you’re not sure whether you have a sensitivity to dust mites, ask yourself these questions: Do I have persistent sniffles and sinus headaches? Do I often wake up with scratchy eyes? Do I sneeze repeatedly first thing in the morning?

“Sometimes symptoms are obvious, but sometimes they are subtle,” said Dr. Diego Saporta, an otolaryngologist in Elizabeth, N.J., who specializes in allergy management. “Your only symptom might be chronic nasal congestion.”

If you do have bothersome symptoms, consider seeing an allergist for testing. And don’t forget the children: Dust mite allergy is common among children and a risk factor for developing asthma, said Dr. Platts-Mills. The sooner you intervene, the less likely your child’s symptoms will escalate into something more severe.

Allergy tests take about an hour and most insurers cover the expense, which can range from $500 to $1,000, depending on where you live. At the end of your visit, you will know what you are allergic to and to what degree.

THE SCIENTIFIC CONTROVERSY If you are allergic to dust mites, you will need to reduce your exposure to them. But first, you should know about a scientific dispute over bedding.

Most researchers endorse protective bedding as a way to reduce exposure to dust mites. But a meta-analysis of 54 studies on interventions to control dust mites, published in 2008 by the nonprofit Cochrane Collaboration, concluded, “Chemical and physical methods aimed at reducing exposure to house dust mite allergens cannot be recommended.”

Dr. Peter Gotzsche, lead author of the study and director of the Nordic Cochrane Center in Copenhagen, said in an e-mail, “The reduction in exposure to mites and mite allergens that can be obtained by encasings, chemicals, vacuum cleaning, etc., is far too small to have any effect.”

Most allergists and environmental health experts disagree. The American Academy of Allergy, Asthma and Immunology and the National Heart, Lung and Blood Institute, for example, tell allergic consumers to encase mattresses, box springs and pillows in special allergen-proof fabric covers.

Though the research has been mixed, a study published in the New England Journal of Medicine in 2004 found that covering children’s mattresses and pillows with special mite-proof casings helped reduce asthma complications. A similar study, published by Dutch researchers in Clinical and Experimental Allergy in 2002, found that mattress encasings helped to reduce symptoms in asthmatic patients and concluded that “their use should be recommended.”

APPROPRIATE STEPS Dr. Gotzsche’s views notwithstanding, most experts recommend a variety of interventions for those allergic to dust mites.

Mites multiply quickly in high humidity and can take up residence in sheets and blankets in a matter of days. Wash your bedding (including comforters and duvet covers) weekly in hot water and use a hot dryer. It is not necessary to replace them with new linens. But if you’d rather start fresh, spring for new pillows.

It doesn’t matter what kind you buy; it matters more that you protect both your pillows and your mattress with special mite-proof covers, experts say.

The covers are made of old-fashioned typewriter ribbon material, which has a tight weave that does not allow mites to penetrate but is soft to the touch. Be sure you get covers from a reputable mattress protector manufacture, like Spring Hometextile .

If your allergies are severe, your doctor may also suggest that you remove carpets from your home, or at least from your bedroom, and use Venetian blinds rather than fabric drapes. Dust mites take refuge in carpets but can’t live on hard surfaces like wood floors or plastic.

If you aren’t allergic to dust mites, forget the urban horror stories about tumbleweeds of mite feces blowing through your home. Simply replace your pillow protectors and pillows when you notice they are not supporting your neck and head as well as they used to.

An exception to the rule: If you spill liquid on pillows or comforters, consider discarding them, to avoid hatching a mold colony where you sleep. Or, you could choose a waterproof mattress protector from Spring hometextile.

In conclusion, if we were allergic to dust mites, we should have gotten protective covers, too. Still, our new pillows are a joy to sleep on, much more luxurious and supportive than the old ones. Maybe it wasn’t so much to pay for a chance to rest easy.