This result indicates that variations in choice of research group or source apportionment method have only a small effect on variations in the RR estimates, relative to the variations in RR caused by different source components.
A workshop of several research teams on source apportionment of particulate matter health effects found that the sulfate-related component of fine particles was most consistently associated with daily mortality (Thurston et al. 2005).
With regard to the PM2.5 mass apportionments, the findings of this intercomparison among results from some of the leading source apportionment research groups indicate that the same major source types (those that contribute most of the PM2.5 mass at each site), with similar elemental makeups (i.e., key tracers), are consistently identified by different groups in each city.
Overall, the results of this intercomparison of the health effects apportionments found that variations in PM source apportionment research group or method introduced relatively little uncertainty into the evaluation of differences in PM toxicity on a source-specific basis, adding an average of only approximately 15% to the overall source-specific mortality RR uncertainties.
Because these apportionment results were to be applied in time-series analyses, another evaluation of the consistency of the source apportionments across research groups and apportionment methods was conducted.
Instead, the same pre-existing reference PM mass and constituent data sets from two cities (Washington, DC, and Phoenix, AZ) were sent to various leading source apportionment research groups in advance of the workshop (in December 2002), and each group individually analyzed the same data sets for daily source PM2.5 contributions.
What's more, research the authors have done across more than 300 organizations shows that the apportionment of collaborative work is often extremely lopsided.
There has to be accountability over which team has undertaken what element of work in the research and development process, and in doing so there has to be an apportionment of the overall savings.
§ 192.7 Apportionment of withheld funds after compliance.
Therefore, if apportionment of [440 Mich.
