21.1 Kids on the frontlines of asthma research

For 10-day stretches during 2003 and 2004, forty-five asthmatic kids from smoggy Los Angeles County, some as young as 9, carried more than books in their backpacks. The kids, from two regions of the county, wore backpacks containing small monitors that sampled the air around them continuously as they went about their daily lives—going to class, playing with friends, having dinner with their families.

Children have a lot to teach us about asthma. It’s not just that the respiratory disorder more commonly afflicts kids than adults—which it does. (In the United States, 10% of children have asthma, compared to 7.7% of adults. In Canada, about 15% of children have asthma, as do 8.5% of adults.) Or that research on children with asthma is on the rise. No, in fact, children are actually conducting some of the seminal research on asthma themselves.

And those personal air monitors are far more accurate than measurements taken at local monitoring stations, explains Ralph Delfino, an epidemiologist at the University of California, Irvine, who with his colleagues, recruited the students to help collect the data. “A monitoring station can be many miles from where the subject lives, where they go to school, etc.—so that measurement may not represent their actual exposure very well,” he says. The air monitors used in Defino’s study detected levels of harmful pollutants in the air surrounding each individual child.

The children selected for the experiment were all currently being treated for mild to moderate asthma and the area they all lived in had significant vehicle air pollution. Each child wore a backpack containing a monitor that would continuously sample the air around the child for 10 consecutive days; the monitor measured the amount of small particles and nitrogen dioxide (NO₂), both of which are commonly present in vehicle emissions and are known to irritate lung tissue. Exposure to these pollutants can trigger asthma symptoms such as wheezing, coughing, or shortness of breath in sensitive individuals.

Ten times a day, the children exhaled into a special bag that assessed their breath for nitric oxide (NO), a chemical marker of airway inflammation—a telltale symptom of asthma.

When the 10 days were over, Delfino compared the types of pollutants to which the kids were exposed with their nitric oxide levels at similar points in time. The goal was to paint a picture of the types and amounts of pollutants that exacerbate asthma.

Asthma is a respiratory ailment marked by inflammation and constriction of the narrow airways of the lungs. Delfino’s work is important in part because asthma is one of the most common chronic childhood diseases in the United States, Canada, and other developed nations and a major cause of childhood disability. The United Kingdom has the highest incidence of asthma, with more than 15% of its population diagnosed in 2006 (compared to 14.1% in Canada and 10.9% in the United States). Developing nations are also seeing a rise in asthma, especially in urban centres. In all areas, asthma rates are likely underdiagnosed.

In North America, asthma is the leading cause of school absences. The prevalence of childhood and adolescent asthma has increased by 25-75% per decade during the period since 1960. Currently, 35.5 million people in the United States and Canada are diagnosed with asthma. Because there are more adults than children, overall more adults have asthma, but a larger percentage of children have the disease.

Researchers believe that air pollution—contaminants, either from natural sources or human activities, that cause health or environmental problems—may play a key role in the recent asthma spike. In addition, air pollution has been linked to cancer, infection, and other respiratory diseases—and it not only harms us, but also plants, animals, and even our buildings, bridges, and statues.