When wildfires sweep through Southern California, more than houses, trees and firefighters are in danger. Children, even healthy ones without asthma, suffer serious respiratory symptoms from breathing smoke, according to a USC study to be published today.
The researchers questioned the parents of nearly 5,000 children after the October 2003 wildfires that burned more than 1,000 square miles in Southern California, creating plumes of smoke.
Wheezing, coughing, colds, bronchitis, sore throats, sneezing and irritated eyes were among the children's symptoms. Many parents reported that their sons and daughters missed school and visited doctors' offices because of these problems.
The study suggests that children can stay healthier during wildfires if they limit outdoor activity and take other precautions recommended by public health agencies.
Asthmatics suffered the most symptoms, but there was also a high frequency of respiratory problems among children without the disorder -- so much so that many seemed as if they had asthma, the researchers reported in the American Journal of Respiratory and Critical Care Medicine.
"One thing this study shows us is that during severe wildfires, children who do not have asthma may be experiencing what it is like to live with asthma," said Dr. Nino Kunzli, lead author of the study and an associate professor of preventive medicine at USC's Keck School of Medicine.
The study, involving first-, second-, and 12th-graders in 16 cities, is the first large-scale investigation of the consequences of wildfires on children's health.
Questionnaires were filled out by 4,609 parents who are participating in a long-term project researching the health effects of air pollution in Southern California and on the Central Coast.
Twelve of the communities were directly affected by the fires or had dense smoke. Of those, Upland, Mira Loma and San Bernardino recorded the worst smoke levels, although Long Beach, Riverside, San Dimas, Glendora and Anaheim were among others with smoky air.
During two weeks in 2003, multiple fires roared through all six Southern California counties, burning 1,200 square miles and destroying 3,640 homes.
Smoke hovered over the Los Angeles Basin for days, and airborne particulates reached 10 to 20 times usual levels. In addition to pieces of soot that can irritate airways and lodge in lungs, smoke contains toxic gases.
"We confirmed very substantial effects of wildfire smoke exposure on eyes as well as upper and lower respiratory symptoms, in both asthmatics and non-asthmatics," the study says. The increase in respiratory problems was strongest among children without asthma, apparently because asthmatics took preventive action, such as staying indoors, wearing masks and using air conditioners.
Kunzli said non-asthmatics reported as many health problems on the smoky days as asthmatics do on smoke-free days.
Parents of one of every five non-asthmatic children reported that the children were coughing during the fires, compared with one of every two to three asthmatic children. About 7% reported wheezing by non-asthmatic children, while for asthmatic children, it was one-third. About 13% of all the children missed school.
The health problems for non-asthmatic children were somewhat unexpected, said Jean Ospital of the South Coast Air Quality Management District, which co-funded the study.
"We generally think people with chronic diseases are more sensitive, but this shows that we're all sensitive to the effects of smoke and we have to worry about everyone, not just people with asthma," he said. "This study reinforces what we think is the right thing to do, to advise people to avoid exposure to smoke whenever they can."
Sneezing or stuffy noses were the most frequent symptom, reported by 41% of the parents, followed by irritated eyes, reported by more than 35%.
Although it's not unusual for children to suffer frequent stuffy noses and coughs, the rates of such symptoms rose substantially in the smokiest areas.
Parents of children in the communities with the highest particulate levels reported three times more eye irritation and twice as much coughing, nose symptoms and sore throats than those in less smoky areas. Also, those who smelled smoke indoors for more than six days reported wheezing and other respiratory problems two to five times more frequently than those with low smoke exposure. Asthma attacks increased 63% in the smoky areas.
Dr. Sverre Vedal of the University of Washington said in an editorial accompanying the report that it may seem obvious that people suffer respiratory problems during wildfires. He said, however, that the study was important to determine who is most susceptible and the full range of their symptoms.
But Vedal said there are likely biases in the data, because the researchers relied on parents' memories and focused on specific symptoms. "Although we know there are health impacts from exposure to wildfire smoke, we remain uncertain about the range and severity," he wrote.