United States Department of Agriculture

Forest 

Service

Pacific Northwest 

Research Station

General Technical Report

PNW-GTR-925 May

2016

Smoke Management Photographic 

Guide: A Visual Aid for 

Communicating Impacts

Joshua C. Hyde, Jarod Blades, Troy Hall, Roger D. Ottmar, and Alistair Smith
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Authors

Joshua C. Hyde is a program coordinator, University of Idaho, College of Natural 

Resources, 400 North 34th Street, Suite 201, Seattle, WA 98103; Jarod Blades is an 

assistant professor, University of Wisconsin, Plant and Earth Sciences, 410 South 

Third Street, River Falls, WI 54022; Troy Hall is the head of the Department of 

Conservation Social Sciences, Oregon State University, College of Forestry, 321 

Richardson Hall, Corvallis, OR 97331; Roger D. Ottmar is a research forester, 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station, 400 North 34th Street, Suite 201, Seattle, WA 98103; Alistair Smith is an 

associate professor, University of Idaho, College of Natural Resources, 975 West 

Sixth Street, Moscow, ID 83844.

Published in cooperation with: the University of Idaho—College of Natural 

Resources and the Joint Fire Science Program.
Abstract

Hyde, Joshua C.; Blades, Jarod; Hall, Troy; Ottmar, Roger D.; Smith, Alistair. 

2016. Smoke management photographic guide: a visual aid for communicating 

impacts. Gen. Tech. Rep. PNW-GTR-925. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station. 59 p.

Communicating emissions impacts to the public can sometimes be difficult because 

quantitatively conveying smoke concentrations is complicated. Regulators and 

land managers often refer to particulate-matter concentrations in micrograms per 

cubic meter, but this may not be intuitive or meaningful to everyone. The primary 

purpose of this guide is to serve as a tool for communicating potential particulate 

matter (PM2.5) levels during wildfire events using visual representation. Examples 

of visibility impairment under various levels of smoke concentration and humidity 

have been modeled using the WinHaze program.

Keywords: Air quality, regional haze, smoke management.
Contents

1 Introduction

1 Methods

3 Using This Guide

4 Limitations

5 English Equivalents

5 Acknowledgments

5 Literature Cited

8 Appendix

8 Northern Region (National Forest System—Region 1):

Selway-Bitterroot Wilderness and Glacier National Park (Montana)

14 Intermountain Region (National Forest System—Region 2): 

Rocky Mountain National Park (Colorado)

18 Southwestern Region (National Forest System—Region 3):

Grand Canyon National Park (Arizona)

24 Rocky Mountain Region (National Forest System—Region 4): 

Canyonlands National Park (Utah)

28 Rocky Mountain Region (National Forest System—Region 4): 

Great Basin National Park (Nevada)

32 Pacific Southwest Region (National Forest System—Region 5):

Yosemite National Park (California)

36 Pacific Northwest Region (National Forest System—Region 6):

Columbia River Gorge National Scenic Area (Oregon)

40 Pacific Northwest Region (National Forest System—Region 6):

Snoqualmie Pass (Washington)
44 Southern Region (National Forest System—Region 8):

Great Smoky Mountains National Park (Tennessee)

48 Southern Region (National Forest System—Region 8):

Mammoth Cave National Park (Kentucky)

52 Southern Region (National Forest System—Region 8):

Big Bend National Park (Texas)

56 Eastern Region (National Forest System—Region 9):

Acadia National Park (Maine)
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Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Introduction

An important but difficult part of determining the impacts of emissions from 

wildland fire on air quality is the preparation of a quantitative smoke-concentration 

assessment. Although smoke is composed of a variety of chemical compounds and 

other components, regulators and land managers often focus on particulate matter 

(PM) owing to its effects on human health and visibility degradation. Particulate 

matter in smoke generally ranges from 0.1 to 100 micrometers (μm) in diameter 

(Hardy et al. 2001). Diameters ≤10 μm (PM10) and ≤2.5 μm (PM2.5) are the most 

common size classes used in air quality measurement and monitoring. Particulate 

matter concentration is measured in units of micrograms per cubic meter (μg/m3).

Visibility is affected by several factors, including the composition and concentration of smoke from fires. Particulate matter emitted from fires can contain 

ammonium nitrate, ammonium sulfate, and light-absorbing carbon (Malm et al. 

1994). The effect these compounds have on visibility can be magnified by increases 

in relative humidity, which causes more water vapor to adhere to particles thereby 

altering the way they absorb and reflect light (Malm et al. 2003). In addition, background levels of visibility vary geographically (Hand et al. 2014, Malm et al. 1994).

This guide illustrates the effects of wildland fire smoke on visibility for the 

continental United States (fig. 1). It was developed with images from locations in 

national parks and other scenic areas to assess visibility impairment associated with 

elevated PM2.5 concentration through visual representation. Images presented in 

this guide were generated using WinHaze (Air Resource Specialists, Inc. 2013), a 

software tool developed to visualize the impacts of pollution on visibility.1 Because 

of the complex relationships that influence observed visual range approximations—

contrasts perceived by the naked eye, the effects of these contrasts on perception 

of visual range, and the effects of both of these factors on particle-concentration 

estimates—they should be used as general indicators, not precise measurements.

Methods

This reference guide was generated using WinHaze imaging software version 

2.9.9.1. (Air Resource Specialists, Inc. 2013) for the purpose of representing visual 

impacts from smoke in numerous U.S. locations. To determine the reduction in 

visibility, WinHaze incorporates several years of particulate monitoring data and 

images from national parks and wilderness areas into a beta extinction equation 

1

 The use of trade or firm names in this publication is for reader information and does not 

imply endorsement by the U.S. Department of Agriculture of any product or service.

This guide will help 

air quality regulators 

and land managers 

communicate PM2.5

concentrations during 

wildland fires.
2

GENERAL TECHNICAL REPORT PNW-GTR-925

Northern (Region 1): Selway-Bitterroot Wilderness 

(south), Glacier National Park (north)

Intermountain (Region 2): Rocky Mountain 

National Park

Southwestern (Region 3): Grand Canyon National 

Park (both)

Rocky Mountain (Region 4): Canyonlands National 

Park (east), Great Basin National Park (west)

Pacific Southwest (Region 5): Yosemite National 

Park

Pacific Northwest (Region 6): Columbia River 

Gorge National Scenic Area (south), Snoqualmie 

Pass (north)

Southern (Region 8): Great Smoky Mountains 

National Park (east), Mammoth Cave National 

Park (center), Big Bend National Park (west)

Eastern (Region 9): Acadia National Park

Figure 1—Locations of sites where estimations of decreased visibility were 

converted into photo images (grey dots). The sites selected represent typical 

conditions in each of the National Forest System regions of the contiguous U.S. 

states.

(Hand and Malm 2006); the equation, images, and data are products of the Interagency Monitoring of Protected Visual Environments (IMPROVE) program, which 

has placed stationary cameras and air quality monitoring equipment at several 

national parks (http://vista.cira.colostate.edu/improve/Default.htm. [15 June 2015]).

WinHaze allows for consistent visual representation of air quality under 

varying levels of humidity, background pollution, and PM2.5 concentration. Each 

example in this guide presents a simulated baseline image that represents the 

visual range under average PM concentrations juxtaposed with several images of 

simulated visual impairment. Visual impairment from smoke was simulated first 

by establishing constant values for the PM2.5 constituents that would be unlikely 

to change with the introduction of smoke from fires; values for ammonium sulfate, 

ammonium nitrate, and fine soil were calculated by averaging the 20 percent worst 

visibility days. Organic carbon and black carbon—which account for nearly 75 

percent of the emissions from forest fires (Andreae and Merlet 2001)—were then 

increased to reflect increasing concentrations of smoke using an organic-carbon 

to black-carbon ratio of 15.4:1 (Andreae and Merlet 2001). The coarse particulate 

inputs used to simulate each image were chosen based on the larger of two values: 

either the average value of the 20 percent worst monitored days, or 10 percent of the 

PM2.5 (ammonium sulfate, ammonium nitrate, fine soil, organic carbon, and black 

carbon) concentration (Ward and Hardy 1991). 

The version of WinHaze used for this work includes the first version of the 

IMPROVE beta extinction equation, as described in Hand and Malm (2006). To 
3

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

improve the accuracy of the simulations by accounting for hygroscopicity (Malm 

et al. 2005)—the ability of a substance to attract and hold water molecules from the 

surrounding environment—a correction factor was applied to the organic carbon 

values before each image and visual range determination was generated; accordingly, light scattering (total beta extinction) of organic carbon increased linearly 

by a factor of 1.2 at 80-percent relative humidity compared to no relative humidity. 

Each image includes prominent landmarks with which to judge visual range. The 

distance between the camera locations and each landmark was measured with 

Google Earth and verified using location information from Air Resource Specialists, Inc.

Relative humidity affects visibility and changes throughout the day and from 

one season to the next; therefore, a range of values was chosen to represent morning and afternoon monthly averages most likely to occur during the wildland fire 

season (May to September) in all national park and wilderness-area locations (EPA 

2014). Because these data were unavailable for the two Pacific Northwest (Region 

6) locations (fig. 1), meteorological station data were chosen from a location as 

geographically close to the available site as possible (NOAA 2014).

Lipsett et al. (2012) and the Environmental Protection Agency (EPA 2013) 

define five levels for air quality: good, moderate, unhealthy for sensitive groups, 

unhealthy, and very unhealthy (table 1). These levels correspond to thresholds for 

action by public health officials: good requires no action, moderate suggests sensitive populations reduce prolonged or heavy exertion, unhealthy for sensitive groups 

requires warnings or alerts to those with heart or lung conditions or other pertinent 

health issues, unhealthy requires that all people should be notified, regardless of 

health status, and very unhealthy recommends everyone should avoid physical 

activity outdoors (Lipsett et al. 2012). The PM2.5 levels that were chosen for display 

in this guide were good (<38 μg/m3

), unhealthy for sensitive groups (89 to 138 μg/

m

3

), and unhealthy (139 to 351 μg/m3) for a short period of time (up to 3 hours) 

because they are sufficiently different as to be easily discernable to the naked eye. 

The mid-point of each range was chosen to represent each health level: 19 μg/m3 for 

good, 114 μg/m3 for unhealthy for sensitive groups, and 245 μg/m3 for unhealthy.

Using This Guide

Each set of images in this guide is preceded by a description of the air quality data 

for the site depicted, including the date range and number of sampling days of PM 

data used by WinHaze, the source for the relative humidity data, a table listing the 

constituents of smoke (both PM2.5 and PM10) represented in the images, and a table 

Each set of images 

includes tables 

documenting the 

constituents of 

particulate matter 

(PM) at different 

concentration levels, 

and visual range 

at different relative 

humidity and PM 

concentrations levels.

Public health officials 

may recommend 

different actions based 

on the concentration of 

smoke in the area.
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GENERAL TECHNICAL REPORT PNW-GTR-925

Table 1—Images and visual range estimates representing the particulate matter 

(PM) concentration mid-points of the good (19 μg/m3), unhealthy for sensitive 

groups (114 μg/m3

), and unhealthy (245 μg/m3) categories were chosen for 

display in this guide 

Air quality

PM10 or PM2.5

concentration 

(μg/m3) a b Actions required to protect health

Good 0 to 38 - No action needed.

Moderate 39 to 88 - Unusually sensitive people should consider

reducing prolonged or heavy exertion.

Unhealthy for 

sensitive groups

89 to 138 - People with heart or lung disease, children, 

and older adults should reduce prolonged or 

heavy outdoor exertion.

- Everyone else should limit prolonged or heavy 

exertion.

Unhealthy 139 to 351 - People with heart or lung disease, children, 

and older adults should avoid all physical 

activity outdoors.

- Everyone else should avoid prolonged or 

heavy exertion.

Very unhealthy >351 - People with heart or lung disease, children, 

and older adults should remain indoors and 

keep activity levels low.

- Everyone else should avoid all physical

activity outdoors.

a

 PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in diameter, respectively.

b

 Concentrations are 1- to 3-hour averages.

Source: Adapted from Lipsett et al. (2012) and EPA (2013).

listing all of the visible range distances for each PM2.5 concentration and relative 

humidity level.

To use this guide for visualizing PM2.5 concentration, select the region and 

location that best matches the terrain and humidity conditions of the location you 

are assessing and compare your line-of-sight with landmarks located at distances 

that correspond to those shown in the photographs. Unless no distinction could be 

made between photographs, as sometimes occurs at the higher PM2.5 concentration 

levels, images are included that represent baseline (smoke free), good (19 μg/m3), 

unhealthy for sensitive groups (114 μg/m3), and unhealthy (245 μg/m3) conditions 

for each location.

Limitations

Visual range is simulated based on analyses of both air quality data and the constituents of wildland fire smoke. Images included in this guide were generated 
5

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

independently of one factor (sun angle) that has an effect on visibility (Malm and 

Schichtel 2013, Middleton 1968). Also, the PM2.5 concentration levels for good, 

unhealthy for sensitive groups, and unhealthy conditions shown in the photographs 

are not instantaneous “snapshots,” but are based on average levels over a period of 

1 to 3 hours. This is important because visual ranges can change relatively rapidly.

English Equivalents

When you know: Multiply by: To find:

Micrometers (μm) 0.039 Mils

Micrograms (μg) 0.00002 Grains

Kilometers (km) 0.62 Miles

Acknowledgments

We acknowledge funding from the Joint Fire Science Program under Project JFSP 

10-1-03-2. The authors would also like to thank members of the National Wildfire 

Coordinating Group Smoke Committee for their comments and feedback during 

the development of this guide. Mark Fitch, William Malm, Susan O’Neill, and 

Janice Peterson provided helpful reviews. Robert Vihnanek, Carol Whitlock, and 

Clint Wright provided production and editorial assistance.

Literature Cited

Air Resource Specialists, Inc. 2013. WinHaze. Version 2.9.9.1. http://www.airresource.com/resources/ downloads.html. (20 June 2015).

Andraea, M.O.; Merlet, P. 2001. Emission of trace gases and aerosols from 

biomass burning. Global Biogeochemical Cycles. 15(4): 955‒966.

Hand, J.L.; Malm, W.C. 2006. Review of the IMPROVE equation for estimating 

ambient light extinction coefficients—final report. http://vista.cira.colostate.edu/ 

improve/publications/graylit/016_IMPROVEeqReview/IMPROVEeqReview.htm. 

(17 June 2015).

Hand, J.L.; Schichtel, B.A.; Malm, W.C. [et al.]. 2014. Widespread reductions in 

haze across the United States from the early 1990s through 2011. Atmospheric 

Environment. 94: 671‒679.

Hardy, C.C.; Ottmar, R.D.; Peterson, J.L.; Core, J.E.; Seamon, P., eds. 2001.

Smoke management guide for prescribed and wildland fire: 2001 edition. 

NFES 1279. Boise, ID: National Interagency Fire Center, National Wildfire 

Coordinating Group, Fire Use Working Team. 226 p.
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GENERAL TECHNICAL REPORT PNW-GTR-925

Lipsett, M.; Materna, B.; Stone, S.L. [et al.]. 2012. Wildfire smoke: a guide for 

public health officials. Rev. U.S. Environmental Protection Agency. 53 p. http://

oehha.ca.gov/air/risk_assess/wildfirev8.pdf. (17 June 2015).

Malm, W.C.; Day, D.E.; Kreidenweis, S.M.; Collett, J.L., Jr.; Lee, T. 2003.

Humidity-dependent optical properties of fine particles during the Big Bend 

Regional Aerosol and Visibility Observational Study. Journal of Geophysical 

Research. 108(D9): 4279.

Malm, W.C.; Day, D.E.; Kreidenweis, S.M. [et al.]. 2005. Hygroscopic properties 

of an organic-laden aerosol. Atmospheric Environment. 39: 4969‒4982.

Malm, W.C.; Schichtel, B.A. 2013. Uncertainty associated with estimating a 

short-term (1–3 hr) particulate matter concentration from a human-sighted visual 

range. Joint Fire Science Program Project Report. 105 p. http://digitalcommons.

unl.edu/jfspresearch/5/. (17 June 2015).

Malm, W.C.; Sisler, J.F.; Huffman, D.; Eldred, R.A.; Cahill, T.A. 1994. Spatial 

and seasonal trends in particle concentration and optical extinction in the United 

States. Journal of Geophysical Research. 99(D1): 1347‒1370.

Middleton, W.E.K. 1968. Vision through the atmosphere; corrected edition. 

Toronto, Canada: University of Toronto Press. 250 p.

National Oceanic and Atmospheric Administration [NOAA]. 2014. Quality 

controlled local climatological data. Version 2.5.5. http://cdo.ncdc.noaa.gov/ 

qclcd/QCLCD?prior=N. (20 June 2015).

U.S. Environmental Protection Agency [EPA]. 2013. Air quality guide for 

particle pollution. 2 p. http://www.epa.gov/airnow/air-quality-guide_pm_2013.

pdf. (17 June 2015).

U.S. Environmental Protection Agency [EPA]. 2014. Clean air status and 

trends network (CASTNET). http://epa.gov/castnet/javaweb/index.html.

(21 January 2015).

Ward, D.E.; Hardy, C.C. 1991. Smoke emissions from wildland fires. 

Environment International. 17(2‒3): 117‒134.
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Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
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GENERAL TECHNICAL REPORT PNW-GTR-925

Appendix

Northern Region (National Forest System—Region 1):

Selway-Bitterroot Wilderness and Glacier National Park 

(Montana)

Particulate data from 1,037 days of sampling (March 1988 to May 1999) at Glacier 

National Park were chosen to represent baseline and elevated regional air quality 

concentrations (table 2). Table 3 shows the simulated visual range at different levels 

of PM2.5 concentration (<5, 19, 114, and 245 μg/m3) and relative humidity for both 

the Selway-Bitterroot Wilderness and Glacier National Park. The simulated images 

show a baseline representing an area free of smoke-impaired visibility (<5 μg/m3

fine and coarse particulates) and two or three levels of impairment (table 1). Data 

used for estimating the effect of relative humidity on visual range during the May 

to September fire season are from Glacier National Park (EPA 2014).

Table 2—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<5 μg/m3) and elevated (19, 114, and 

245 μg/m3) levels in the Selway-Bitterroot Wilderness 

and Glacier National Park, Montana

Particulate matter 

constituents

Particulate matter concentration

<5 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 0.96 1.29 1.29 1.29

Ammonium nitrate 0.30 0.61 0.61 0.61

Organic carbon 2.67 14.95 104.14 227.13

Black carbon 0.43 0.97 6.78 14.79

Fine soil 0.58 1.19 1.19 1.19

Coarse mass 6.12 10.21 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
9

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 3—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in the Selway-Bitterroot Wilderness and 

Glacier National Park, Montana

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<5 (Baseline) 40 72.7 117.0

19 (Good) 40 24.6 39.6

60 23.1 37.2

80 21.3 34.3

90 19.9 32.1

114 (Unhealthy for Sensitive Groups) 40 4.4 7.1

60 4.2 6.8

80 4.0 6.5

90 3.9 6.3

245 (Unhealthy) 40 2.1 3.3

50 to 60 2.0 3.2

70 to 90 1.9 3.1 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
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GENERAL TECHNICAL REPORT PNW-GTR-925

Selway-Bitterroot Wilderness (Montana)
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Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
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GENERAL TECHNICAL REPORT PNW-GTR-925

Glacier National Park (Montana)
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Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
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Intermountain Region (National Forest System—Region 2): 

Rocky Mountain National Park (Colorado)

Particulate data from 794 days of sampling (September 1990 to May 1999) at Rocky 

Mountain National Park were chosen to represent baseline and elevated regional 

air quality concentrations (table 4). Table 5 shows the simulated visual range at 

different levels of PM2.5 concentration (<5, 19, 114, and 245 μg/m3) and relative 

humidity for Rocky Mountain National Park. The simulated images show a baseline 

representing an area free of smoke-impaired visibility (<5 μg/m3 fine and coarse 

particulates) and three levels of impairment (table 1). Data used for estimating the 

effect of relative humidity on visual range during the May to September fire season 

are from Rocky Mountain National Park (EPA 2014).

Table 4—Constituents of particulate matter (PM2.5 and 

PM10) at Baseline (<5 μg/m3) and elevated (19, 114, and 245 

μg/m3

) levels in Rocky Mountain National Park, Colorado

Particulate matter 

constituents

Particulate matter concentration

<5 (baseline) 19 114 245

μg/m3

Ammonium sulfate 0.93 1.49 1.49 1.49

Ammonium nitrate 0.29 0.50 0.50 0.50

Organic carbon 1.00 14.77 103.96 226.95

Black carbon 0.17 0.96 6.77 14.78

Fine soil 0.63 1.28 1.28 1.28

Coarse mass 3.96 5.88 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
15

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 5—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in Rocky Mountain National Park, Colorado

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<5 (Baseline) 40 107.5 173.0

19 (Good) 40 25.4 40.9

50 24.6 39.6

60 23.8 38.3

114 (Unhealthy for Sensitive Groups) 40 4.4 7.1

50 4.3 7.0

60 4.2 6.8

245 (Unhealthy) 40 2.1 3.3

50 to 60 2.0 3.2 a PM2.5 is composed of particles that are ≤2.5 μm in diameter.
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GENERAL TECHNICAL REPORT PNW-GTR-925

Rocky Mountain National Park (Colorado)
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Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
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GENERAL TECHNICAL REPORT PNW-GTR-925

Southwestern Region (National Forest System—Region 3): 

Grand Canyon National Park (Arizona)

Particulate data from 857 days (March 1988 to August 1998) at Grand Canyon 

National Park were chosen to represent baseline and elevated regional air quality 

concentrations (table 6). Table 7 shows the simulated visual range at different levels 

of PM2.5 concentration (<3, 19, 114, and 245 μg/m3) and relative humidity for two 

viewing locations at Grand Canyon National Park. The simulated images show a 

baseline representing an area free from smoke-impaired visibility (<3 μg/m3 fine 

and coarse particulates) and two or three levels of impairment (table 1). Data used 

for estimating the effect of relative humidity on visual range during the May to 

September fire season are from Grand Canyon National Park (EPA 2014).

Table 6—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<3 μg/m3) and elevated (19, 114, and 

245 μg/m3

) levels in Grand Canyon National Park, Arizona

Particulate matter 

constituents

Particulate matter concentration

<3 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 1.01 1.59 1.59 1.59

Ammonium nitrate 0.20 0.31 0.31 0.31

Organic carbon 0.80 14.90 104.09 227.08

Black carbon 0.18 0.97 6.78 14.79

Fine soil 0.61 1.23 1.23 1.23

Coarse mass 4.99 7.16 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
19

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 7—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in Grand Canyon National Park, Arizona

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<3 (Baseline) 10 109.4 176.0

19 (Good) 10 26.4 42.5

20 26.0 41.8

30 25.6 41.2

40 25.1 40.4

50 24.4 39.2

60 23.5 37.9

114 (Unhealthy for Sensitive Groups) 10 4.7 7.6

20 4.6 7.4

30 4.5 7.3

40 4.4 7.1

50 4.3 7.0

60 4.2 6.8

245 (Unhealthy) 10 2.2 3.5

20 to 40 2.1 3.4

50 2.0 3.2

60 1.9 3.1 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
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GENERAL TECHNICAL REPORT PNW-GTR-925

Grand Canyon National Park (Arizona)—Bluff View 
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Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
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GENERAL TECHNICAL REPORT PNW-GTR-925

Grand Canyon National Park (Arizona)—Valley View
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Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
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GENERAL TECHNICAL REPORT PNW-GTR-925

Rocky Mountain Region (National Forest System—Region 4): 

Canyonlands National Park (Utah)

Particulate data from 964 days (March 1988 to May 1999) at Canyonlands National 

Park were chosen to represent baseline and elevated regional air quality concentrations (table 8). Table 9 shows the simulated visual range at different levels of PM2.5

concentration (<3, 19, 114, and 245 μg/m3) and relative humidity for Canyonlands 

National Park. The simulated images show a baseline representing an area free 

from smoke-impaired visibility (<3 μg/m3 fine and coarse particulates) and three 

levels of impairment (table 1). Data used for estimating the effect of relative humidity on visual range during the May to September fire season are from Canyonlands 

National Park (EPA 2014).

Table 8—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<3 μg/m3

) and elevated (19, 114, and 245 

μg/m3) levels in Canyonlands National Park, Utah

Particulate matter 

constituents

Particulate matter concentration

<3 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 1.08 1.54 1.54 1.54

Ammonium nitrate 0.23 0.37 0.37 0.37

Organic carbon 0.82 14.77 103.96 226.95

Black carbon 0.16 0.96 6.77 14.78

Fine soil 0.69 1.36 1.36 1.36

Coarse mass 5.60 8.43 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
25

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 9—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in Canyonlands National Park, Utah

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<3 (Baseline) 10 106.3 171.0

19 (Good) 10 26.3 42.4

20 26.0 41.8

30 25.5 41.1

40 25.0 40.3

114 (Unhealthy for Sensitive Groups) 10 4.7 7.6

20 4.6 7.4

30 4.5 7.3

40 4.4 7.1

245 (Unhealthy) 10 2.2 3.5

20 to 40 2.1 3.4 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
26

GENERAL TECHNICAL REPORT PNW-GTR-925

Canyonlands National Park (Utah)
27

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
28

GENERAL TECHNICAL REPORT PNW-GTR-925

Rocky Mountain Region (National Forest System—Region 4): 

Great Basin National Park (Nevada)

Particulate data from 681 days of sampling (May 1992 to May 1999) at Great Basin 

National Park were chosen to represent baseline and elevated regional air quality 

concentrations (table 10). Table 11 shows the simulated visual range at different 

levels of PM2.5 concentration (<3, 19, 114, and 245 μg/m3) and relative humidity for 

Great Basin National Park. The simulated images show a baseline representing an 

area free from smoke-impaired visibility (<3 μg/m3 fine and coarse particulates) 

and two levels of impairment (table 1). Data used for estimating the effect of relative 

humidity on visual range during the May to September fire season are from Great 

Basin National Park (EPA 2014).

Table 10—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<3 μg/m3) and elevated (19, 114, and 

245 μg/m3

) levels in Great Basin National Park, Nevada

Particulate matter 

constituents

Particulate matter concentration

<3 (Baseline) 19 114 245

μ/gm3

Ammonium sulfate 0.68 1.13 1.13 1.13

Ammonium nitrate 0.16 0.31 0.31 0.31

Organic carbon 0.98 15.18 104.37 227.37

Black carbon 0.19 0.99 6.80 14.81

Fine soil 0.60 1.39 1.39 1.39

Coarse mass 3.73 5.50 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
29

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 11—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in Great Basin National Park, Nevada 

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<3 (Baseline) 20 115.0 185.0

19 (Good) 20 26.2 42.2

30 25.8 41.6

40 25.4 40.8

50 24.7 39.7

114 (Unhealthy for Sensitive Groups) 20 4.6 7.4

30 4.5 7.3

40 4.4 7.1

50 4.3 7.0

245 20 to 40 2.1 3.4

50 2.0 3.3 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
30

GENERAL TECHNICAL REPORT PNW-GTR-925

Great Basin National Park (Nevada)
31

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
32

GENERAL TECHNICAL REPORT PNW-GTR-925

Pacific Southwest Region (National Forest System—Region 5): 

Yosemite National Park (California)

Particulate data from 951 days (March 1988 to May 1999) at Yosemite National 

Park were chosen to represent baseline and elevated regional air quality concentrations (table 12). Table 13 shows the simulated visual range at different levels of 

PM2.5 concentration (<5, 19, 114, and 245 μg/m3) and relative humidity for Yosemite National Park. The simulated images show a baseline representing an area free 

from smoke-impaired visibility (<5 μg/m3 fine and coarse particulates) and three 

levels of impairment (table 1). Data used for estimating the effect of relative humidity on visual range during the May to September fire season are from Yosemite 

National Park (EPA 2014).

Table 12—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<5 μg/m3) and elevated (19, 114, and 245 

μg/m3) levels in Yosemite National Park, California

Particulate matter 

constituents

Particulate matter concentration

<5 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 0.99 1.90 1.90 1.90

Ammonium nitrate 0.47 0.94 0.94 0.94

Organic carbon 1.94 14.20 103.39 226.38

Black carbon 0.27 0.92 6.73 14.74

Fine soil 0.56 1.04 1.04 1.04

Coarse mass 4.78 7.64 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
33

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 13—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in Yosemite National Park, California

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<5 (Baseline) 20 85.7 138.0

19 (Good) 20 26.2 42.1

30 25.8 41.5

40 25.2 40.6

50 24.4 39.2

114 (Unhealthy for Sensitive Groups) 20 4.6 7.4

30 4.5 7.3

40 4.4 7.1

50 4.3 7.0

245 (Unhealthy) 20 2.1 3.4

50 2.0 3.2 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
34

GENERAL TECHNICAL REPORT PNW-GTR-925

Yosemite National Park (California)
35

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
36

GENERAL TECHNICAL REPORT PNW-GTR-925

Pacific Northwest Region (National Forest System—Region 6): 

Columbia River Gorge National Scenic Area (Oregon)

Particulate data from 551 days of sampling (July 1993 to May 1999) in the Columbia River Gorge National Scenic Area were chosen to represent baseline and 

elevated regional air quality concentrations (table 14). Table 15 shows the simulated 

visual range at different levels of PM2.5 concentration (<6, 19, 114, and 245 μg/m3) 

and relative humidity for the Columbia River Gorge National Scenic Area. The 

simulated images show a baseline representing an area free from smoke-impaired 

visibility (<6 μg/m3 fine and coarse particulates) and three levels of impairment 

(table 1). Data used for estimating the effect of relative humidity on visual range 

during the May to September fire season are from Portland, Oregon (NOAA 2014).

Table 14—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<6 μg/m3) and elevated (19, 114, and 245 

μg/m3

) levels in the Columbia River Gorge National Scenic 

Area, Oregon

Particulate matter 

constituents

Particulate matter concentration

<6 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 1.48 2.56 2.56 2.56

Ammonium nitrate 0.77 1.78 1.78 1.78

Organic carbon 2.32 12.56 101.75 224.75

Black carbon 0.47 0.82 6.63 14.63

Fine soil 0.66 1.28 1.28 1.28

Coarse mass 7.90 11.88 11.88 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
37

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 15—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in the Columbia River Gorge National Scenic 

Area, Oregon

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<6 (Baseline) 40 66.5 107.0

19 (Good) 40 25.4 40.8

50 24.2 39.0

60 22.9 36.9

70 21.5 34.6

80 19.9 32.0

114 (Unhealthy for Sensitive Groups) 40 4.4 7.2

50 4.3 7.0

60 4.2 6.8

70 4.1 6.6

80 4.0 6.4

245 (Unhealthy) 40 2.1 3.3

50 to 60 2.0 3.2

70 to 80 1.9 3.1 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
38

GENERAL TECHNICAL REPORT PNW-GTR-925

Columbia River Gorge National Scenic Area (Oregon)
39

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
40

GENERAL TECHNICAL REPORT PNW-GTR-925

Pacific Northwest Region (National Forest System—Region 6): 

Snoqualmie Pass (Washington)

Particulate data from 353 days of sampling (December 1993 to May 1999) at 

Snoqualmie Pass were chosen to represent baseline and elevated regional air quality 

concentrations (table 16). Table 17 shows the simulated visual range at different 

levels of PM2.5 concentration (<4, 19, 114, and 245 μg/m3) and relative humidity 

for Snoqualmie Pass. The simulated images show a baseline representing an area 

free from smoke-impaired visibility (<4 μg/m3 fine and coarse particulates) and 

three levels of impairment (table 1). Data used for estimating the effect of relative 

humidity on visual range during the May to September fire season are from SeattleTacoma International Airport, Washington (NOAA 2014).

Table 16—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<4 μg/m3

) and elevated (19, 114, and 245 

μg/m3) levels at Snoqualmie Pass, Washington 

Particulate matter 

constituents

Particulate matter concentration

<4 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 0.98 1.84 1.84 1.84

Ammonium nitrate 0.35 0.59 0.59 0.59

Organic carbon 1.28 14.80 103.99 226.98

Black carbon 0.31 0.96 6.77 14.78

Fine soil 0.29 0.81 0.81 0.81

Coarse mass 2.94 3.82 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
41

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 17—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity at Snoqualmie Pass, Washington

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<4 (Baseline) 50 95.7 154.0

19 (Good) 50 24.5 39.5

60 23.6 38.0

70 22.6 36.3

80 21.4 34.4

90 19.7 31.7

114 (Unhealthy for Sensitive Groups) 50 4.3 7.0

60 4.2 6.8

70 4.1 6.6

80 4.0 6.5

90 3.9 6.3

245 (Unhealthy) 50 2.0 3.2

60 2.0 3.2

70 to 90 1.9 3.1 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
42

GENERAL TECHNICAL REPORT PNW-GTR-925

Snoqualmie Pass (Washington)
43

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
44

GENERAL TECHNICAL REPORT PNW-GTR-925

Southern Region (National Forest System—Region 8): 

Great Smoky Mountains National Park (Tennessee)

Particulate data from 935 days (March 1988 to May 1999) at Great Smoky Mountains National Park were chosen to represent baseline and elevated regional air 

quality concentrations (table 18). Table 19 shows the simulated visual range at 

different levels of PM2.5 concentration (<11, 19, 114, and 245 μg/m3) and relative 

humidity for Great Smoky Mountains National Park. The simulated images show a 

baseline representing an area free from smoke-impaired visibility (<11 μg/m3 fine 

and coarse particulates) and three levels of impairment (table 1). Data used for estimating the effect of relative humidity on visual range during the May to September 

fire season are from Great Smoky Mountains National Park (EPA 2014).

Table 18—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<11 μg/m3

) and elevated (19, 114, and 245 

μg/m3

) levels in Great Smoky Mountains National Park, 

Tennessee

Particulate matter 

constituents

Particulate matter concentration

<11 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 6.42 13.97 13.97 13.97

Ammonium nitrate 0.43 0.31 0.31 0.31

Organic carbon 2.78 3.46 92.66 215.65

Black carbon 0.47 0.23 6.03 14.04

Fine soil 0.55 1.03 1.03 1.03

Coarse mass 5.74 7.23 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
45

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 19—Simulated visual range as a function of PM2.5 concentration 

(μg/m3) and relative humidity in Great Smoky Mountains National Park, 

Tennessee

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<11 (Baseline) 60 38.0 61.2

19 (Good) 60 23.2 37.4

70 19.6 31.5

80 16.2 26.0

114 (Unhealthy for Sensitive Groups) 60 4.2 6.8

70 4.0 6.5

80 3.8 6.1

245 (Unhealthy) 60 2.0 3.2

70 1.9 3.1

80 1.8 2.9 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
46

GENERAL TECHNICAL REPORT PNW-GTR-925

Great Smoky Mountains National Park (Tennessee)
47

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
48

GENERAL TECHNICAL REPORT PNW-GTR-925

Southern Region (National Forest System—Region 8): 

Mammoth Cave National Park (Kentucky)

Particulate data from 1,067 days of sampling (October 1991 to August 2003) at 

Mammoth Cave National Park were chosen to represent baseline and elevated 

regional air quality concentrations (table 20). Table 21 shows the simulated visual 

range at different levels of PM2.5 concentration (<12, 19, 114, and 245 μg/m3) and 

relative humidity for Mammoth Cave National Park. The simulated images show a 

baseline representing an area free from smoke-impaired visibility (<12 μg/m3 fine 

and coarse particulates) and three levels of impairment (table 1). Data used for estimating the effect of relative humidity on visual range during the May to September 

fire season are from Mammoth Cave National Park (EPA 2014).

Table 20—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<12 μg/m3

) and elevated (19, 114, and 245 

μg/m3

) levels in Mammoth Cave National Park, Kentucky

Particulate matter 

constituents

Particulate matter concentration

<12 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 6.94 13.99 13.99 13.99

Ammonium nitrate 0.90 0.65 0.65 0.65

Organic carbon 2.82 3.03 92.22 215.22

Black carbon 0.48 0.20 6.01 14.01

Fine soil 0.58 1.13 1.13 1.13

Coarse mass 4.43 6.26 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
49

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 21—Simulated visual range as a function of PM2.5 concentration

(μg/m3

) and relative humidity in Mammoth Cave National Park, Kentucky

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<12 (Baseline) 50 40.3 64.8

19 (Good 50 27.5 44.2

60 23.4 37.7

70 19.6 31.6

80 16.2 26.0

114 (Unhealthy for Sensitive Groups) 50 4.4 7.1

60 4.2 6.8

70 4.0 6.5

80 3.8 6.1

245 (Unhealthy) 50 2.0 3.3

60 2.0 3.2

70 1.9 3.1

80 1.8 2.9 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
50

GENERAL TECHNICAL REPORT PNW-GTR-925

Mammoth Cave National Park (Kentucky)
51

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
52

GENERAL TECHNICAL REPORT PNW-GTR-925

Southern Region (National Forest System—Region 8): 

Big Bend National Park (Texas)

Particulate data from 973 days of sampling (March 1988 to May 1999) at Big Bend 

National Park were chosen to represent baseline and elevated regional air quality 

concentrations (table 22). Table 23 shows the simulated visual range at different 

levels of PM2.5 concentration (<6, 19, 114, and 245 μg/m3) and relative humidity for 

Big Bend National Park. The simulated images show a baseline representing an area 

free from smoke-impaired visibility (<6 μg/m3 fine and coarse particulates) and 

three levels of impairment (table 1). Data used for estimating the effect of relative 

humidity on visual range during the May to September fire season are from Big 

Bend National Park (EPA 2014).

Table 22—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<6 μg/m3

) and elevated (19, 114, and 245 

μg/m3) levels in Big Bend National Park, Texas

Particulate matter 

constituents

Particulate matter concentration

<6 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 2.47 4.31 4.31 4.31

Ammonium nitrate 0.24 0.42 0.42 0.42

Organic carbon 1.30 10.89 100.08 223.07

Black carbon 0.21 0.71 6.52 14.53

Fine soil 1.20 2.67 2.67 2.67

Coarse mass 7.69 11.82 11.82 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
53

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 23—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in Big Bend National Park, Texas

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<6 (Baseline) 20 77.7 125.0

19 (Good) 20 28.0 45.1

30 27.7 44.5

40 27.0 43.5

50 25.7 41.3

60 24.2 38.9

70 22.5 36.2

114 (Unhealthy for Sensitive Groups) 20 4.7 7.5

30 4.6 7.4

40 4.5 7.2

50 4.4 7.1

60 4.3 6.9

70 4.2 6.7

245 (Unhealthy) 20 2.2 3.5

30 to 40 2.1 3.4

50 to 60 2.0 3.2

70 1.9 3.1 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
54

GENERAL TECHNICAL REPORT PNW-GTR-925

Big Bend National Park (Texas)
55

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
56

GENERAL TECHNICAL REPORT PNW-GTR-925

Eastern Region (National Forest System—Region 9): 

Acadia National Park (Maine)

Particulate data from 986 days of sampling (March 1988 to May 1999) at Acadia 

National Park were chosen to represent baseline and elevated regional air quality 

concentrations (table 24). Table 25 shows the simulated visual range at different 

levels of PM2.5 concentration (<6, 19, 114, and 245 μg/m3) and relative humidity for 

Acadia National Park. The simulated images show a baseline representing an area 

free from smoke-impaired visibility (<6 μg/m3 fine and coarse particulates) and 

two levels of impairment (table 1). Data used for estimating the effect of relative 

humidity on visual range during the May to September fire season are from Acadia 

National Park (EPA 2014).

Table 24—Constituents of particulate matter (PM2.5 and 

PM10) at baseline (<6 μg/m3

) and elevated (19, 114, and 245 

μg/m3) levels in Acadia National Park, Maine

Particulate matter 

constituents

Particulate matter concentration

<6 (Baseline) 19 114 245

μg/m3

Ammonium sulfate 3.07 6.83 6.83 6.83

Ammonium nitrate 0.37 0.71 0.71 0.71

Organic carbon 1.59 10.42 99.61 222.60

Black carbon 0.34 0.68 6.49 14.50

Fine soil 0.22 0.36 0.36 0.36

Coarse mass 4.66 5.78 11.40 24.50

Note: PM10 and PM2.5 are composed of particles that are ≤10 μm and ≤2.5 μm in 

diameter, respectively.
57

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 

Table 25—Simulated visual range as a function of PM2.5 concentration

(μg/m3) and relative humidity in Acadia National Park, Maine 

PM2.5 concentrationa Relative humidity Visual range

Percent Miles Kilometers

<6 (Baseline) 50 66.5 107.0

19 (Good) 50 25.0 40.2

60 22.9 36.9

70 20.7 33.3

80 18.4 29.6

114 (Unhealthy for Sensitive Groups) 50 4.3 7.0

60 4.2 6.8

70 4.1 6.5

80 3.9 6.3

245 (Unhealthy) 50 to 60 1.9 3.1

70 1.8 2.9

80 1.7 2.7 a

 PM2.5 is composed of particles that are ≤2.5 μm in diameter.
58

GENERAL TECHNICAL REPORT PNW-GTR-925

Acadia National Park (Maine)
59

Smoke Management Photographic Guide: A Visual Aid for Communicating Impacts 
Pacific Northwest Research Station

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