Description:
Effects of PM10 on Mortality
1. Particulate matter background
Particulate matter is one of six "criteria pollutants" identified by the United States EPA. Other criteria pollutants include carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (03), and sulfur dioxide (SO2). The EPA has established the National Ambient Air Quality Standards (NAAQS) for all criteria pollutants found at http://www.epa.gov/airs/criteria.html .
High particulate concentrations in the atmosphere have been linked to rises in the number of hospital visits for upper respiratory infections, cardiac disorders, bronchitis, asthma, pneumonia, emphysema, and similar respiratory problems. The report listed below (see Background of Data) links particulate matter with daily mortality. As a category of criteria pollutant, particulate matter is complex with size, chemical composition, and atmospheric concentration all important characteristics. The original NAAQS did not take size into account until 1987, when standards were changed to monitor PM10 (particulate matter less than 10 micrometers). This change was made because particles larger than 10 micrometers are quite effectively removed from the upper respiratory system by sneezing, coughing, or swallowing mucus. Smaller particles have better chance of reaching the lungs. Recently the EPA has extended its monitoring to include PM2.5 (particulate matter less than 2.5 micrometers) .
2. Background of Data
These data were obtained from "The National Morbidity, Mortality, and Air Pollution Study Part II", funded by the Health Effects Institute (HEI), June 2000. The Health Effects Institute provides information on the health effects of motor vehicle emissions, and typically receives half its funds from the US EPA and half from 28 manufacturers and marketers of motor vehicles in the US. The Health Effects Institute web site is found at http://www.healtheffects.org/ and as of July, 2000, the full report could be downloaded.
HEI states that "epidemiological time series studies conducted in a number of cities have identified, in general, an association between daily changes in ambient particulate matter (PM) and daily number of deaths (mortality). The National Morbidity, Mortality, and Air Pollution Study (NMMAPS) attempts to "characterize the effects of airborne particles less than 10 microns in aerodynamic diameter (PM10 ) alone and in combination with gaseous air pollutants in a consistent way, in a large number of cities." The study was led by Dr. Jonathan Samet at Johns Hopkins University, and investigated the effects of PM10 in both the 20 and 90 largest cities in the US. Both the 20 cities and 90 cities analyses agree that there is an "average approximate 0.5% increase in overall mortality for every 10µg/m3 increase in PM10 measured the day before death."
3. Suggestions for using the data in the classroom
Discuss and interpret the mean and median of the mortality numbers.
Discuss and interpret the 95% confidence interval and compute the standard deviation.
Construct a histogram of the mortality numbers and identify any outliers.
Obtain PM10 daily readings for a given city from the EPA's Airs Database and observe the variability. What does the NMMAPS report predict in lieu of these daily fluctuations?
