Appendix 7 - Acute Impacts Refined Analysis 
Refined Acute Modeling Approach 

Initial acute screening risk calculations were performed with the HEM-3 

model. HEM-3 estimates acute (1-hour) impacts at both polar and census block 

receptors. It is assumed for this short period of time that an exposed individual 

could be located at any off-site location. The lack of readily available detailed 

property boundary information for many of the facilities evaluated made it difficult 

to determine whether receptors were on- or off-site. In the absence of such 

information, the first ring of polar receptors was placed 100 meters from the plant 

center for many facilities. However, these polar rings often transected on-site 

locations, restricting public access to exposures at these levels and thereby 

overestimating exposures. 

 The screening approach used by HEM-3 to estimate maximum 1-hour 

exposures also likely overestimates. To estimate maximum 1-hour 

concentrations at each receptor, HEM-3 sums the maximum concentrations 

attributed to each source, regardless of whether those maximum concentrations 

occurred during the same hour. In other words, HEM-3 assumes that the 

maximum impact from each source at each receptor occurs at the same time. In 

actuality, maximum impacts from different sources may occur at different times. 

 This appendix includes the results of refined acute assessments 

performed for facilities that exceeded short-term health benchmarks using the 

HEM-3 approach. The refinements can address both areas of conservatism 

described above. The simplest refinement is to plot the HEM-3 polar grid results 

on aerial photographs of the facilities; this allows the assessment of off-site 

locations that may be accessible to the public (e.g., roadways and public 

buildings.). The attached figure present the estimated hazard quotient values 

(the modeled 1-hour concentration of a pollutant divided by its short-term health 

benchmark) at the polar receptors near the facilities. 
HEM‐3

(Screening)

Refined

Results

NEI32636 Formaldehyde REL 34 20

Examined results for maximum off-site impact 

(Figure 1)

NEI11202 Formaldehyde REL 3 3

Examined results for maximum off-site impact 

(Figure 2)

NEI11393 Formaldehyde REL 5 3

Examined results for maximum off-site impact 

(Figure 3)

NEI11431 Formaldehyde REL 4 3

Examined results for maximum off-site impact 

(Figure 4)

NEI12037 Formaldehyde REL 14 8

Examined results for maximum off-site impact 

(Figure 5)

NEI25015 Formaldehyde REL 16 11

Examined results for maximum off-site impact 

(Figure 6)

NEI32855 Formaldehyde REL 30 30

Examined results for maximum off-site impact 

(Figure 7)

NEIGA1210021 Formaldehyde REL 2 2

Examined results for maximum off-site impact 

(Figure 8)

Wool Fiberglass Manufacturing - Actual Emissions - Post Control

NEI11202 Formaldehyde REL 3 2

Examined results for maximum off-site impact 

(Figure 9)

NEI11393 Formaldehyde REL 2 1

Examined results for maximum off-site impact 

(Extrapolated from Figure 10)

NEI11431 Formaldehyde REL 4 3

Examined results for maximum off-site impact 

(Figure 11)

NEI12037 Formaldehyde REL 3 2

Examined results for maximum off-site impact 

(Figure 12)

NEI32855 Formaldehyde REL 7 5

Examined results for maximum off-site impact 

(Figure 13)

Wool Fiberglass Manufacturing - Actual Emissions

1 Indicates modeling technique used to refined estimates; see  figures depicting off‐site impacts

Table 1 – Maximum Predicted Acute Risks Greater than 1 (Refined Approach)

Facility NEI ID Pollutant Criteria Refined  Modeling Approach 1

Baseline ‐ Actuals

Mineral Wool Production - Actual Emissions
Figure 1 – NEI32636 Formaldehyde HQ (REL)
Figure 2 – NEI11202 Formaldehyde HQ (REL)
Figure 3 – NEI11393 Formaldehyde HQ (REL)
Figure 4 – NEI11431 Formaldehyde HQ (REL)
Figure 5 – NEI12037 Formaldehyde HQ (REL)
Figure 6 – NEI25015 Formaldehyde HQ (REL)
Figure 7 – NEI32855 Formaldehyde HQ (REL)
Figure 8 – NEIGA1210021 Formaldehyde HQ (REL)
Figure 9 – NEI11202 Formaldehyde HQ (REL)
Figure 10 – NEI11393 Formaldehyde HQ (REL)
Figure 11 – NEI11431 Formaldehyde HQ (REL)
Figure 12 – NEI12037 Formaldehyde HQ (REL)
Figure 13 – NEI32855 Formaldehyde HQ (REL)