Asthma is a long-term, often progressive, disease in which swelling of the lining of the airways, narrowing of the passageway and making breathing difficult. For people with asthma, some inflammation is always present, even when symptoms are absent. Asthma may be triggered by allergens (a substance such as pollen, causing an allergy), irritants, exercise and respiratory infections (i.e. cold). Successful asthma treatment has four key elements: measurement of lung function (how much air moves in and out of the lungs), avoidance of triggers, proper medication and patient education.

Asthma is a chronic inflammatory disorder of the respiratory system (airways and lungs) that results in chronic and relapsing symptoms including cough, chest tightness, wheezing, and shortness of breath. While the cause of asthma remains unknown, this disorder is becoming increasingly common in the U.S. and around the world. Asthma is the most common chronic disease in childhood and affects approximately 15 million Americans.

In the United States, about 17 million people of all ages, races, and nationalities have asthma. Asthma can occur at any age but most commonly begins during the first 5 years of life.

Nearly 1 in 12 school-age children has asthma, and that percentage is rising more rapidly in preschool-aged children than in any other group. Asthma is the most common chronic illness of childhood and is the leading cause of school absenteeism due to a chronic illness.

The impact of asthma falls disproportionately on African-American and certain Hispanic populations and appears to be particularly severe in urban inner cities.

Asthma, like other allergic disorders, runs in families and has a genetic basis, although the details of the genes responsible for asthma are not fully understood at the present time.

Even with the rising rate of asthma in the United States, many cases of asthma likely go undiagnosed or are misdiagnosed

Asthma is the most common long-term childhood disease, affecting 4.8 million children. Nearly 1 in 12 school-aged children has asthma, and the percentage of children with asthma is rising more rapidly in preschool-aged children than in any other age group.

Asthma accounts for one-third of all pediatric emergency room visits and is the fourth most common cause for physician office visits. Asthma is the leading cause for hospitalization in children's hospitals. Asthma is one of the leading causes of school absenteeism, accounting for over 10 million missed school days per year. Asthma also accounts for many nights of interrupted sleep, limitation of activity, and disruptions of family and care-giver routines. Asthma symptoms that are not severe enough to require a visit to an emergency room or to a physician can still be severe enough to prevent a child with asthma from living a fully active life. With appropriate therapy, nearly all children can have entirely normal lives without the need to restrict activities due to asthma symptoms or the fear of development of symptoms.

When asthma causes breathing problems, the breathing problems are called asthma attacks or episodes of asthma.

During an asthma attack, three major changes that can take place in the lungs include:

1. Cells in the air tubes make more mucus than normal. This mucus is very thick and sticky, and tends to clog up the tubes.

2. Cells in the airways get inflamed, causing the air tubes to swell.

3. The muscles around the air tubes tighten.

These changes cause the air tubes to narrow which makes it hard to breathe.

Asthma attacks can be caused by something that bothers the lungs. These are called asthma triggers. There are many kinds of asthma triggers. Two major categories of asthma triggers are allergens and irritants.

Examples of allergens which have been shown to trigger asthma are house dust mites, cat dander, dog dander, cockroach feces, molds, and pollens (from trees, grasses and weeds). Irritants which may trigger asthma include tobacco smoke, strong odors (perfumes, cleaning products) and pollutants (sulfur dioxide). Other triggers of asthma episodes are exercise (especially in cold, dry air), viral respiratory tract infections (such as the common cold), medications (such as aspirin and beta-blockers), and chemicals (such as sulfites in wine).

If you, or a loved one has asthma, it's important to learn which triggers are a problem. Ask your doctor to help. Your doctor may suggest keeping an asthma diary or recommend skin testing for allergies.

Once asthma triggers are known, actions can be taken to prevent asthma attacks. Cutting down exposure to your triggers may help in avoiding asthma attacks. When attacks occur, they may be less severe

There are many asthma triggers. Two large categories of triggers are allergens and irritants.

Allergens are substances that cause no problem for many people but which trigger an allergic reaction in people who have allergies and thus make antibodies (or proteins) against these otherwise innocuous substances. During an allergy attack, the allergen causes body to release chemicals called mediators. These mediators can trigger asthma episodes.

Irritants such as cold air, cigarette smoke, industrial chemicals, perfume, and paint and gasoline fumes can trigger asthma. These irritants probably trigger asthma symptoms by stimulating irritant receptors in the respiratory tract. These receptors, in turn, cause the muscles surrounding the airway to narrow, resulting in an asthma attack.

Viral infections are a leading cause of acute asthma episodes. Surprisingly, bacterial infections, with the exception of sinusitis, generally do not bring about asthma attacks.

Since Americans spend up to 90% of their time indoors, exposure to indoor allergens and irritants may play a significant role in causing inflammation in the lungs of patients with asthma and making those patients more susceptible to asthma episodes.

The following is a list of some of indoor environmental triggers of asthma:

secondhand cigarette smoke

cockroaches

dust mites

molds

pets and other animals with fur or feathers

ozone

by-products of combustion

pollen from trees, grass, and weeds.

If you have asthma, you probably want to know how to reduce your chances of having an asthma episode and what to do once you have an asthma episode. Your doctor will be able to assist you. Consult your physician to set up an asthma management plan. Your doctor can help you learn to monitor your asthma, take appropriate medication for your asthma, and identify and avoid your asthma triggers. Following your asthma management plan will help keep your asthma under control.

The goals of asthma therapy appear to be quite lofty but are achievable in most patients:

Prevent chronic and troublesome symptoms

Maintain "normal" lung function

Maintain normal activity levels (including exercise and other physical activity)

Prevent recurrent episodes of asthma

Minimize (ideally eliminate) the need for emergency department visits or hospitalizations

Provide optimal medications with minimal or no side effects

Meet patients' and families' expectations of satisfaction with asthma care