Appendix 6 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.). In cases where this refinement results in lower acute 

risks no further refinement was conducted. However, if acute risk still remain at or near 

levels of concern a further refinement is conducted. This second refinement includes 

remodeling with the AERMOD model directly (instead of using HEM) to estimate 

maximum 1-hour concentrations at each receptor by pairing individual source impacts in 

time and space. The AERMOD results are then plotted on aerial photographs as noted 

above to determine off-site impacts. Modeling with AERMOD also allows the 

estimation of the frequency of higher impacts at or above the health levels of concern. 

The attached figures 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. Each set of figures is prefaced with a description of the 

maximum off-site hazard quotient value and where that value occurs. Refer to below for 

a brief summary;
• NEI46835; maximum offsite acute HQ(REL) for acetaldehyde of 20; northeast of 

facility

• NEI42338 chloroform acute HQ(REL) of 6, south of the facility

• NEITN1050093; maximum offsite acute HQ(REL) for chloroform of 5 to the north 

of facility

• NEI13363; maximum offsite acute HQ(REL) for formaldehyde of 5 to the northeast 

of facility

• NEI42341A; maximum offsite acute HQ(REL) for chloroform of 4 to the north of 

facility

• NEIWI7720116; maximum offsite acute HQ(REL) for acetaldehyde of 3, north of 

the facility

• NEIWI7720116; maximum offsite acute HQ(REL) for methanol of 2; southeast of 

facility

• NEIME0250002; maximum offsite acute HQ(REL) for acetaldehyde of 2 ; east of 

facility

• NEIWI7720116; maximum offsite acute HQ(REL) for chloroform of 2, southeast of 

the facility

• NEI47104; maximum offsite acute HQ(REL) for acetaldehyde of 2 to the northwest 

of the facility

• NEI41552; maximum offsite acute HQ(REL) for acetaldehyde of 2; northeast of 

facility 
23029NEI46835 Acetaldehyde REL 15.2 15.2

Max off-site HQ with emission specific 

multipliers

53015NEI42338 Chloroform REL 39.0 6

Max off-site HQ with emission specific 

multipliers

47105NEITN1050093 Chloroform REL 5.2 5.2

Max off-site HQ with emission specific 

multipliers

53053NEI13363 Formaldehyde REL 4.6 4.6

Max off-site HQ with emission specific 

multipliers

53015NEI42341A Chloroform REL 4.1 4.1

Max off-site HQ with emission specific 

multipliers

55141NEIWI7720116 Acetaldehyde REL 4.3 2.9

Max off-site HQ with emission specific

multipliers

55141NEIWI7720116 Methanol REL 3.4 2.3

Max off-site HQ with emission specific 

multipliers

23025NEIME0250002 Acetaldehyde REL 1.6 2.3

Max off-site HQ with emission specific 

multipliers; increase in HQ due to max acute 

multiplier = 3 for mechanical seperation of pulp 

versus use of screening multiplier of 2

55141NEIWI7720116 Chloroform REL 3.1 2.1

Max off-site HQ with emission specific 

multipliers

37083NEI47104 Acetaldehyde REL 9.3 1.6

Max off-site HQ with emission specific 

multipliers

47071NEI41552 Acetaldehyde REL 2.1 1.5

Max off-site HQ with emission specific 

multipliers

05069NEI18657 1,2‐Dimethoxyethane REL 8.5 < 1

Max off-site HQ with emission specific 

multipliers

01023NEI18334 Formaldehyde REL 5.7 < 1

Max off-site HQ with emission specific 

multipliers

01023NEI18334 Methanol REL 4.9 < 1

Max off-site HQ with emission specific 

multipliers

Max off-site HQ with emission specific 

Pulp and Papermaking

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

Facility NEI ID Pollutant Criteria

HEM‐3

(Screening)

Refined

Results Refined  Modeling Approach 1

41043NEI13340 Formaldehyde REL 4.7 < 1

a o s te Q t e ss o spec c

multipliers

01023NEI18334 Acetaldehyde REL 4.7 < 1

Max off-site HQ with emission specific 

multipliers

51085NEI208 Chloroform REL 4.2 < 1

Max off-site HQ with emission specific 

multipliers

41071NEI40648 Chloroform REL 3.2 < 1

Max off-site HQ with emission specific 

multipliers

01023NEI18334 Chloroform REL 2.9 < 1

Max off-site HQ with emission specific 

multipliers

05069NEI18658 Chloroform REL 2.9 < 1

Max off-site HQ with emission specific 

multipliers

05069NEI18657 Formaldehyde REL 2.8 < 1

Max off-site HQ with emission specific 

multipliers

41043NEI13340 Acetaldehyde REL 2.6 < 1

Max off-site HQ with emission specific 

multipliers

21107NEI11367 Formaldehyde REL 2.1 < 1

Max off-site HQ with emission specific 

multipliers

13127NEI8196 Acetaldehyde REL 2.0 < 1

Max off-site HQ with emission specific 

multipliers

01091NEI45474 Chlorine REL 1.9 < 1

Max off-site HQ with emission specific 

multipliers

39113NEI11645 Chloroform REL 1.9 < 1

Max off-site HQ with emission specific 

multipliers

12123NEI47091 Chloroform REL 1.7 < 1

Max off-site HQ with emission specific 

multipliers

41043NEI13340 Methanol REL 1.6 < 1

Max off-site HQ with emission specific 

multipliers

13051NEI8186 Formaldehyde REL 1.6 < 1

Max off-site HQ with emission specific 

multipliers
01099NEI18373 Acetaldehyde REL 1.5 < 1

Max off-site HQ with emission specific 

multipliers

1 Indicates modeling technique used to refined estimates; see Appendix 7 for figures depicting off‐site impacts
Pulp and Papermaking Fa

(Refined Acute Risk Asses

• Figure 1 – NEI46835; maximum offs

HQ(REL) for acetaldehyde of 20; north

• Figure 2 – NEI42338 chloroform acu

6, south of the facility

• Figure 3 – NEITN1050093; maximum 

HQ(REL) for chloroform of 5 to the nor

• Figure 4 – NEI13363; maximum offs

HQ(REL) for formaldehyde of 5 to the facility
Pulp and Papermaking Fa

(Refined Acute Risk Asses

• Figure 5 – NEI42341A; maximum of

HQ(REL) for chloroform of 4 to the nor

• Figure 6 – NEIWI7720116; maximum 

acute HQ(REL) for acetaldehyde of 3, 

facility

• Figure 7– NEIWI7720116; maximum 

HQ(REL) for methanol of 2; southeast 

• Figure 8 – NEIME0250002; maximu

acute HQ(REL) for acetaldehyde of 2 

facility
Pulp and Papermaking Fac

(Refined Acute Risk Assess

• Figure 9 – NEIWI7720116; maximum offsite 

for chloroform of 2, southeast of the facility

• Figure 10– NEI47104; maximum offsite acute 

acetaldehyde of 2 to the northwest of the fac

• Figure 11– NEI41552; maximum offsite acute 

acetaldehyde of 2; northeast of facility
Figure 1 – NEI46835 Acute Acetaldehyde HQ (
Figure 2 – NEI42338 Acute Chloroform HQ (
Figure 3 – NEITN1050093 Acute Chloroform HQ 
Figure 4 – NEI13363 Acute Formaldehyde HQ 
Figure 5– NEI42341A Acute Chloroform HQ (R
Figure 6 – NEIWI7720116 Acute Acetaldehyde 
Figure 7 – NEIWI7720116 Acute Methanol HQ 
Figure 8 – NEIME0250002 Acute Acetaldehyde 
Figure 9 – NEIWI7720116 Acute Chloroform HQ 
Figure 10 – NEI47104 Acute Acetaldehyde HQ 
Figure 11 – NEI41552 Acute Acetaldehyde HQ