Firstly if you're allergic, you must make every effort to control the source of the allergen, which may mean getting rid of a pet, removing carpeting and allergen-impermeable encasings, frequent laundering of bedding, and controlling of cockroach populations. Air cleaners cannot substitute for a clean environment.

Many allergies are caused by poor indoor air quality in homes and not just by outdoor pollen from spring flowers and trees.

You should know that there are different types of air cleaners and purifiers. True HEPA filters are the most effective air filters. These are found in both portable cleaners and vacuum cleaners. But they are not the same as "HEPA-like" filters, so beware. Electronic precipitators are also good models, but their efficiency decreases over time. Look for "clean air delivery rate" which measures the amount of clean air delivered per minute. If there is a central heating and air, which constantly circulates contaminated air throughout the house, you should go for a whole-house cleaner for sure.

When you are dealing with allergies, the more serious they are, the purer the air needs to be around you or the person who gets allergies. One person with light allergies may feel fine with a cheaper quality air purifier but somebody else with more severe allergies may find that same machine to be completely ineffective. He might just continue to get dust allergy or mite allergy. The exact nature of allergies or sensitivities is another important factor when choosing an air purifier. Different air purifiers are needed for those suffering from multiple chemical sensitivities or asthma. When you have asthma, it is recommended that you purchase an air purifier with a gas filter to control gases and odors, which can trigger an asthma attack. People with multiple chemical sensitivities can react to almost anything around them, so the correct choice of air purifier is extremely important. Since this person can even react to the material that makes up the air purifier such as glue on the Hepa filter or out gassing from plastic parts it is very important to know the machine in details before you go ahead and buy it. A stronger the gas filter needed when dealing with gas, odor, and chemical situations. It needs to be checked whether there is a high chance of recontamination and what the rate of that is. The concentration of the gas is also to be considered. You would need a basic gas filter if you want to control general cooking odors. While cigarette and cigar smoke requires a very large and powerful gas filter.

All of this need to be checked in order to get an air purifier that will keep you away from allergies. Otherwise even a good air purifier would not be of any or much help. If you do a good research on these points and matters then certainly an air purifier will help you with allergies and asthma. These machines purify the air and remove at least 60% of the allergens from your environment. The rest depends on cleanliness.