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. Author manuscript; available in PMC: 2020 Mar 15.
Published in final edited form as: J Air Waste Manag Assoc. 2019 Oct 15;69(12):1391–1414. doi: 10.1080/10962247.2019.1668498

Table 2.

Summary of county-average 2011 annual mean PM2.5 estimates of AQS+IMPROVE fused data, CDC WONDER, EPHTN and Dalhousie data in contiguous U.S.

PM2.5 data AQS+IMPROVE CDC WONDER EPHTN Dalhousie
Minimum PM2.5 value (μg/m3) 1.7 7.2 4.4 3.3
Maximum PM2.5 value (μg/m3) 20.4 14.9 16.0 13.4
R2 * 0.106** 0.649 0.647
R2 * for PM2.5 < 15 μg m−3 only 0.136** 0.649 0.662
Normalized mean bias * 33.3%** 12.2% −3.3%
Number of samples used in analysis 544 3102 3104 3104
*

R2 and normalized mean bias are calculated based on county-mean to county-mean comparison with respect to AQS+IMPROVE data of 2011 annual mean.

**

This is based on county-mean to county-mean comparison, but as for the grid-level validation, the surfacing algorithm that was used to create the CDC WONDER dataset was also validated on the grid level for the Southeastern US that showed an R2 of 0.88 and RMSE of 1.6 μg/m3 (Al-Hamdan et al., 2009).