Los Angeles area children experience slight lung function losses on days when their exposure to air pollution (ozone, nirtrogen dioxide and air-borne particulates) is higher, according to a new study by USC researchers, William S. Linn and Henry Gong, Jr.
“Short-Term Air Pollution Exposures and Responses in Los Angeles Area School Children,” published recently in the Journal of Exposure Analysis and Environmental Epidemiology, followed 269 children through their fourth- and fifth-grade years. Lung function (maximal forced expiratory tests) and symptoms were measured twice daily for one week each in fall, winter and spring.
The study found that changes in lung function from morning to afternoon became significantly more unfavorable with increases in ozone, airborne particles or nitrogen dioxide. Also, lung function measured in the morning decreased significantly with increases in particles or nitrogen dioxide measured in the preceding 24 hours.
Function changes averaged 1-2 percent on the most-polluted compared with the least-polluted days. Daily symptoms showed no association with current or prior 24-hour pollution, but increased with decreasing temperature.
“The study indicates that day-to-day changes in pollution have subtle effects on children’s breathing, even when the levels are not especially high for Southern California,” said Linn. “This appears to be true both for ozone, which is highest during summer, and for airborne particles and nitrogen dioxide, which tend to be highest during fall. The findings “are something we should not ignore.”
The researchers noted that the findings are not surprising and are generally consistent with other observations of short-term pollution effects elsewhere.
The fact that ordinary day-to-day pollution changes affect children’s lung function has important implications for scientists studying chronic pollution effects, according to the researchers. “In older adult populations, even slight decrements in lung function predict increased chronic illness and death rates,” said Linn. “The same might be true for children. To understand chronic effects from long-term pollution exposure, you must measure long-term lung function changes very precisely, which means that you must allow for effects of short-term exposure such as we observed.”
The study compared children in three Los Angeles-area communities chosen for contrasting air pollution characteristics: Upland, Rubidoux and Torrance. Upland, an inland urban community, and Rubidoux, an inland semi-rural community, are subject to high levels of pollutants but in different patterns. Torrance, an urban costal community, has generally lower pollution levels.
The study follows preliminary results of a 10-year study on the impact of pollution on the health of school-age children presented by USC researchers in May at the 1997 International Conference of the American Thoracic Society and the American Lung Association.
That study found that children with high lifetime exposure to ozone are sicker more often and for longer amounts of time, with nearly 40 percent of excused absences from school due to illnessess related to respiratory trouble.
Linn, a clinical associate professor of preventive medicine, and Gong, a professor of medicine, along with co-authors Debroah Shamoo, Karen Anderson, Ru-Chuan Peng and Jack D. Hackeny, are based at the Environmental Health Service at Rancho Los Amigos Medical Center. Co-author Edward L. Avol, associate professor of preventive medicine, is based at USC. The study was supported by a contract from Southern California Edison.