Asthma / Asthma - The Condition

submitted by Dr. Gary Farr Last Updated February, 13, 2002

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Asthma is a narrowing of airways in the lungs that causes coughing, wheezing and gasping for breath. It has probably been around since cave dwellers slept on furs coated with dust mites and cockroach crud. But why is it on a rampage today when, ironically, we know more than ever about its causes and treatment? "It's a paradox," says N. Franklin Adkinson, professor of medicine at the Johns Hopkins Medical Institutions. "After over a decade of spending large amounts of money investigating this disease, and finding more powerful, less toxic drugs, all of which should benefit patients, the prevalence has doubled" and the death rate has soared. Consider the 300 million air sacs in the human lungs: Small, fragile, exquisitely designed, they are a critical place where body meets world. The goal, naturally, is to exchange gases: Oxygen from incoming air is transferred to the bloodstream.

Asthma is definitely not a do-it-yourself illness. Nor is it something that should be treated only in emergency rooms. If you suspect you have asthma, don't call The Why Files. Call your doc.

In a normal bronchial tube, relaxed muscles and thin walls allow good airflow. In an inflamed tube, tightened muscles, thickened walls, and abundant mucus inhibit air flow. And carbon dioxide and other waste gases in the blood leave with the exhaled air. This gas exchange is the kind of thing you take for granted until it goes bad. In asthma, that deterioration starts when the lung becomes what doctors call "hyper-reactive." Essentially, that means the airways respond too strongly to a stimulus by narrowing. Breathing becomes more difficult; in severe cases, it becomes impossible, and the disease claims another victim.

Typically, asthma occurs in episodes. The sequence starts with an inflammation, often caused by an allergic response to dust mites, animal dandruff, mold or pollen. That inflammation sets the stage for further irritation. "If your airway is provoked by an allergen, then any other allergen will have a greater effect," says Norman Edelman, a lung specialist who is a consultant to the American Lung Association and dean of the Medical School at State University of New York at Stony Brook.

How bad is asthma?

Bad and getting worse. Don't believe us? Then check these numbers:

Doctor and hospital visits due to asthma are up 50 percent in a decade to 14 million per year. That included 1.6 million visits to emergency rooms, the doctor-of-last-resort to many people without health insurance.

Worldwide, the prevalence of asthma ranges from 1.9 percent to 36.7 percent in various countries, according to the International Study of Asthma and Allergy in Children.
 

What's behind the radical rise in this disease?

Too many causes, too much disease

In their search for the causes of asthma, scientists have blamed lots of disgusting stuff, like roach parts and mite scats. They've also found a few asthma triggers that aren't so disgusting, like cold, dry air.

And even a few that should be healthy, like exercise.

Many, indeed most, cases of asthma, particularly among children, have allergies as a major component. Allergies to what? Dust mites, pollen, animal dander (shed skin), cockroaches, and
certain foods. Different people have different allergies, obviously. Intriguingly, an allergen that sets off a sneezing fit may or may not set off an asthma attack -- even in the same person.

Let's stick with this el-grosso train of thought by looking at some of the more revolting asthma triggers.

Disgusting:

• Infection: Viral infections of the respiratory apparatus irritate the tissues and seem to set up asthma attacks. Similarly, bacterial sinus infections can aggravate asthma by causing mucus to drain into the lungs.
• Irritants: Chemicals such as strong perfumes, household cleansers, or industrial dusts and vapors can all irritate the lungs.
• Tobacco smoke: to the smoker or nearby victims, can irritate the airways.
• Gastroesophageal reflux: a "burping up" of acid stomach contents is irritating (and not just to the lungs).
• Roaches: A recent study of asthmatic children in eight inner-city neighborhoods found that similar numbers of children were allergic to roaches (37 percent) and dust mites (35 percent). Yet roach-parts seemed much more potent in triggering asthma: 50 percent of the kids' rooms contained roach allergen, compared to 10 percent containing dust-mite allergen. And the roach-allergic kids who lived in roach-infested houses were admitted to hospitals three times as often as other asthmatic kids in the study. "The combination of cockroach allergy and exposure to high levels of this allergen may help explain the frequency of asthma-related health problems in inner-city children," the researchers concluded.

Are all asthma triggers so disgusting?

Not so disgusting

• Lots of funky stuff -- roach parts, dust mites, even ragweed pollen -- can trigger asthma attacks. But other things can also cause the airways to constrict:
• Drugs and food: As many as 20 percent of adult asthmatics have attacks after exposure to aspirin, non-steroidal anti-inflammatory medicines, or sulfites in food and drink.
• Exercise: An estimated 85 percent of allergic asthmatics wheeze after exercise, with long-distance running and serious cycling being the worst offenders. (Swimming seems particularly benign to asthmatics.)
• Emotions: Stress and fatigue can affect the immune system in ways that start or exacerbate an attack. "Any chronic disease," says Marcus Cohen, an allergist in private practice in Madison, Wis., "is precipitated and made worse by psychosomatic factors."
• Violence: A study by Rosalind Wright of Brigham and Women's Hospital in Boston suggests that children exposed to violence in their neighborhoods (through hearing gunshots or witnessing physical violence) were twice as likely as other children to experience wheezing and to use emergency medicine to dilate their bronchial tubes. "Researchers have been studying the psychological impact of violence on children, but we also need to be looking at the impact of violence on physical disease," Wright said.

Here's more detail on these triggers -- revolting and otherwise.

An industrial disease?

To some experts, this laundry list of triggers point to the general condition of living in an industrial society as the overarching cause of asthma. "We live in houses that are closed, work in businesses that are closed, the windows don't open, and any pollutant is recirculated," says Cohen. "There's a tremendous amount of volatile organic compounds from synthetic carpet and vinyl upholstery that are off-gassing all the time. Almost everything is carpeted, and that's a place for dust mites to multiply." And many energy-efficient houses have moisture problems that promote the growth of mold and mites. "There are a lot of things going on," Cohen concludes.

Edelman agrees that indoor air pollution is a factor, pointing out that people are spending more time inside. There are dust mites, smoke and mold in houses that are closed for energy efficiency. And kids are spending more time in day care, and are getting more viral infections, which predispose them to asthma."

Outdoor air pollution is also an important cause of asthma, he says, "but it's hard to attribute the increase to that, since it's not been increasing for the last 10 years. At the same time, he adds, the Lung Association says the relationship between asthma and air pollution -- particularly fine particles and ground-level ozone -- is clear enough to require federal passage of the proposed air pollution standards. Air that meets the current EPA standards "precipitate asthma attacks," he states.

Deadly statistics

With each 10 microgram increase in airborne fine particles, reports of asthma attacks go up by 3 percent, according to Douglas Dockery of the Harvard School of Public Health.

Overall death and hospitalization rates rise in lockstep with air pollution levels. For example, an increase in airborne fine particles of 100 micrograms per cubic meter increased the death rate by 13 percent in Sao Paolo, Brazil (see "Air Pollution and Mortality..." in the bibliography). Breathing nitrogen oxide, a key component in auto exhaust, exacerbates the lung's allergic reaction to dust mites. The Why Files covered the air pollution standards dispute.

So exactly what is causing the increase in asthma? "The honest answer is that we don't know" the full story, Edelman concludes. "Speaking for the American Lung Association, I'd say it's urgent that we find out what the true cause is."

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