This overview is the second in a series of articles to be published concerning children’s environmental health. Additional articles will appear in the run-up to “Children’s Environmental Health II: A Global Forum for Action,” scheduled for September 8–11, 2001. This conference is sponsored by the Children’s Environmental Health Network and the Canadian Institute of Child Health, and will take place at Georgetown University in Washington, D.C.

(August 2001) Asthma afflicts a rapidly growing number of children in the United States. The total number of children suffering from this chronic disease increased by 75 percent between 1980 and 1994. The illness has grown fastest among the youngest children: The number of children under 5 years of age with asthma surged by 160 percent during that same time period. Today, asthma affects 4.8 million Americans under the age of 18, or one out of every 15 kids. It is the leading chronic illness for children in the United States.

Asthma is a disease of the lungs and airways that manifests itself in wheezing, coughing, and difficulty in breathing. During an asthma attack, the muscles around the airways constrict and tighten, and the lining of the airways becomes inflamed and swollen. The disease can be controlled with medicine, by avoiding certain asthma triggers, and sometimes by limiting specific activities.

Scientists believe that an array of different factors, including genetic predisposition, immune and respiratory factors, infections, and environmental pollutants, potentially contribute to the onset of asthma and most certainly exacerbate it. Some of the environmental agents known or suspected to trigger attacks include outdoor air pollutants such as particulate matter and ozone, as well as a number of indoor air pollutants (particularly tobacco smoke, dust mites, cockroaches, mold, and pesticides). Additionally, nitrogen dioxide and sulfur dioxide, both prominent outdoor air pollutants, have been shown to decrease lung function in asthmatics.

While scientists strive to understand the causes of this disease, it is clear that the cost of asthma in the U.S. is substantial. Every year 300 children die as a result of asthma. In 1997, asthmatic children accounted for almost 220,000 hospital admissions and almost 780,000 emergency room visits. The U.S. Environmental Protection Agency estimates that American children lost 17 million school days that year due to the disease, and that parents lost 5 million work days in order to care for their children with asthma-related illness. The total cost of asthma to the U.S. economy in 1997 was estimated to be as high as $11 billion, with approximately one-third of those costs due to children’s asthma.

Who Has Asthma?

In 1997-98, 5.4 percent of all children in the U.S. had asthma, according to EPA’s America’s Children and the Environment. The highest rates of asthma, 8.3 percent, were found in non-Hispanic black children living in families with incomes below the poverty level. The rate for Hispanic and white non-Hispanic children was approximately 5 percent. Overall, children living below the poverty level had higher rates of asthma than did those children living at or above the poverty level, with rates of 6.2 percent and 5.3 percent, respectively.

Public health officials are puzzled by the differing rates among racial groups and are particularly troubled by the high mortality due to asthma among African American children. For example, in 1993, among children under age 5, African American children were six times more likely to die from asthma than white children. One recent report has implicated poverty, not race, as the key factor in the higher prevalence rates.

Why the Increase in Asthma?

What changes over the last several decades can account for the startling rise in asthma rates? It is unlikely that the dust mite and cockroach populations have changed significantly, nor can genetics explain this increase.

One dramatic change in recent decades is the variety of chemicals to which many children are exposed, especially in the indoor air they breathe. New materials are being used in building construction and maintenance. Energy-efficient buildings often have ventilation patterns that recycle the air — which contains allergens and pollutants — reducing indoor air quality. Consumer products such as furniture, particle board, and synthetic rugs can emit irritants such as formaldehyde. Some products, such as detergents, cleaning products, and deodorizers, can contain chemicals that irritate the respiratory system. Children from a very young age and in utero are exposed to many of these contaminants in different combinations on a daily basis. Public health experts are now raising questions about the impact of exposure to these pollutants.

According to Dr. Frederica Perera of the Columbia University Center for Children’s Environmental Health, “The role of in utero and early post-natal environmental exposures in conjunction with nutritional and genetic factors may hold the key to prevention.” One research project currently underway at Columbia is exploring possible links between signs of asthma in very young children and exposure to allergens and pollutants in their homes and outdoor environment. Researchers are also looking at sensitization to these substances in utero, which may predispose children to asthma.

Other scientists such as Dr. Peyton Eggelston of the Johns Hopkins University Center for Children’s Environmental Health Research believe that the important exposures occur after birth. This research has looked in particular at infectious bacterial and viral exposures that may contribute to onset of the disease.

What Is Being Done? What Needs To Be Done?

For those children in poor or racial minority communities, where rates of asthma are higher and health outcomes more severe, better access to health care, better housing, and better nutrition, as well as healthier environments, are key strategies for minimizing the effects of the disease.

While the treatment of asthma has appropriately received increasing attention, few resources are dedicated to the prevention of asthma or to tracking the asthma epidemic. In 1999, just a small portion of the federal asthma research budget was spent on asthma etiology (17 percent), prevention (9 percent), or tracking (less than 1 percent).

Currently there is no federal tracking system or registry for asthma in the United States similar to the system that exists for childhood cancer. An asthma tracking system could tell us the incidence and prevalence of the disease, as well as linking these variables to environmental exposures. This information can be used to analyze trends, to help determine causes, to better understand the role of the environment, and to help develop effective prevention strategies.

Since air quality is linked to asthma, policies limiting exposure to indoor and outdoor air pollutants are vital. Currently no federal regulations for indoor air pollution exist. However, many states have policies to decrease exposure to environmental tobacco smoke. Federal air quality standards for ozone and particulate matter were recently strengthened to better protect children’s health. However, these improvements are currently being challenged in the courts and in Congress, and standards for other pollutants are inadequate.

Just as asthma has no single cause, there is no single solution to the asthma epidemic. Our efforts must address asthma on all fronts — prevention as well as treatment. Only then will we see a decrease in the number of children ill and dying due to this modern epidemic.


Joy E. Carlson, MPH, is co-founder and former director of the Children’s Environmental Health Network. She is currently a principal of J. Carlson Consulting. Carol Stroebel is president of Coalition Resources, Inc., a policy consulting firm specializing in health and injury prevention issues.