Air pollution and health effects: A study of medical visits among children in Santiago, Chile.

Many epidemiological studies conducted in the last several years have reported associations between exposure to airborne particulate matter, measured as PM10 (<10 microm in diameter), and daily morbidity and mortality. However, much of the evidence involves effects on the elderly population; there is less evidence about the effects of particulates on children, especially those under 2 years of age. To examine these issues, we conducted time-series analyses of 2 years of daily visits to primary health care clinics in Santiago, Chile, where counts were computed for either upper or lower respiratory symptoms and for cohorts of children 3-15 years of age and below age 2. Daily PM10 and ozone measurements and meteorological variables were available from instruments located in downtown Santiago. The multiple regression analysis indicates a statistically significant association between PM10 and medical visits for lower respiratory symptoms in children ages 3-15 and in children under age 2. PM10 is also associated with medical visits related to upper respiratory symptoms in the older cohort, while ozone is associated with visits related to both lower and upper respiratory symptoms in the older cohort. For children under age 2, a 50- microg/m3 change in PM10 (the approximate interquartile range) is associated with a 4-12% increase in lower respiratory symptoms. For children 3-15 years of age, the increase in lower respiratory symptoms ranges from 3 to 9% for a 50- microg/m3 change in PM10 and 5% per 50 ppb change in ozone. These magnitudes are similar to results from studies of children undertaken in Western industrial nations.

Air pollution and mortality: results from a study of Santiago, Chile.

In 1986, the U.S. EPA issued an air quality standard for particulate matter that included only particulates below 10 microns in diameter (PM10). Unfortunately, epidemiological research investigating the health effects associated with PM10 has been limited by the lack of available daily data from outdoor monitoring stations. Evidence of high concentrations of PM10 in Eastern Europe and in metropolitan areas such as Mexico City and Santiago, Chile underscores the need to evaluate the association between air pollution and mortality. Over the last few years, daily measures of ambient PM10 have been collected in Santiago. Our analysis examines the relationship between PM10 and daily mortality between 1989 and 1991. In addition to total daily mortality, the data were compiled to record total mortality for all males, all females, and those over 65, and mortality from either respiratory disease or cardiovascular disease. Multiple regression analysis was used to explain mortality, with particular attention to controlling for the influence of season and temperature. The results suggest a strong association between PM10 and all of the alternative measures of mortality. The association persists after controlling for daily minimum temperature and binary variables indicating temperature extremes, the day of the week, the month, and the year. Additional sensitivity analyses suggest a fairly robust relationship. In general, a 10 micrograms/m3 change in daily PM10 was associated with a 1% increase in mortality. This relative risk is consistent with the results of recent studies undertaken in the United States.