Acute health effects of fine particulate air pollution in Seattle.

Many epidemiologic studies have found (weak) associations between concentrations of fine particulate pollution in the air on a given day and numbers of deaths, heart attacks, and hospitalizations, on the same day or following days.  Most of these studies have been carried out in cities where fine particle concentrations are highest in summer, and where the main sources of these particles are coal-burning power plants or diesel engines. 

In Seattle, the concentrations of fine particles are highest in the winter, and woodsmoke is a major source.  If similar associations with deaths or hospitalizations are also seen in Seattle it is less likely that the associations are explained by confounding. Confounding is an important issue because the estimated health effects of fine particles are very small, substantially smaller than the variations expected from changes in temperature or other seasonally varying factors such as influenza epidemics.

In http://faculty.washington.edu/tlumley/data/airpoll.dat you have daily data on pollution, weather, and hospital admissions for asthma and for all respiratory diseases in Seattle over an eight-year period (1987-1994). The file contains:

date:		Date, in days since 1-1-1960
dow:    	Day of the week, with Sunday=1,Monday=2,...
yr:		Year: 1=1987, 2=1988,...
mo:		Month
admyng:	Number of hospital admissions for all respiratory diseases on that day in Seattle 			hospitals, for people aged 5-65 years
astyng:		Number of hospital admissions for asthma on that day in Seattle hospitals, for 			people aged 5-65 years
pm25:		24-hour average of concentration of fine particles (below 2.5 microns 				aerodynamic diameter)
temp:		Daily maximum temperature (Fahrenheit)
o3max8:	Highest 8-hour average concentration of ozone. Ozone is measured only in 			summer; the concentrations are thought to be  low in winter
so2avg:	24-hour average of sulfur dioxide concentration.  
coavg:		24-hour average of carbon monoxide concentration.
stagno:		Air stagnation index: the number of hours in the day with little or no wind.

The pollution measurements (pm25, o3max8, so2avg,coavg) are averaged over all the available monitors in the Seattle area. There is only one monitor for sulfur dioxide, and it is near the only important source of sulfur dioxide pollution in the area.  Ozone and sulfur dioxide are known to have respiratory effects at sufficiently high concentrations, but the concentration of sulfur dioxide in Seattle is low.  Carbon dioxide is not thought to have effects on respiratory disease at the concentrations we see in Seattle.

Questions:

1.	Describe how air pollution concentrations vary with season and weather
2.	Describe how rates of hospitalization vary with season and weather
3.	Is there evidence of an effect of fine particle air pollution on hospitalization for asthma or for respiratory disease in general?

 

Hand in a report of not more than 10 pages by August 13.  We will discuss the reports in the final week of class.