Basic Smoke Management Practices

October 2011

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Fire is an essential ecological disturbance, providing many benefits to 

the environment in terms of wildlife, water and soil quality, and 

nutrient cycling. Prescribed burning can also be a means of 

protecting air quality by mitigating the occurrence of large wildfires

and reducing invasive species. However, fire produces smoke which 

contains particulate matter (PM), ozone precursors, greenhouse 

gases, and other trace gases. Basic Smoke Management Practices 

(BSMPs) applied on prescribed burns can mitigate the impacts of 

smoke to public health, public safety and nuisance, and visibility. 

Smoke is not like other air pollution sources--a direct control cannot 

be put on it such as can be applied to a power plant smoke stack--

rather a variety of environmental factors must be taken into account

to manage both the burn and the smoke from the burn. BSMPs 

outlined here offer a suite of options that a fire manager can utilize to 

reduce the impacts of their smoke. The Smoke Management Guide 

for Prescribed and Wildland Fire, 2001 edition 

(http://www.treesearch.fs.fed.us/pubs/5388) and the national smoke 

management website (http://www.nifc.gov/smoke) offer further 

technical information on how to manage smoke. 

The six BSMPs discussed in this Technical Note (and summarized in Table 1) have applicability depending 

on the type of burn, fuels to be burned and level of effort needed to address air quality concerns. Not all 

BSMPs are applicable to all situations, therefore fire managers are urged to investigate the information 

available and applicable to their area and needs. Furthermore, these six BSMPs are only a subset of 

possible BSMPs and others can be adopted as needed such as no burning after November 15 due to 

inversions. BSMP’s are utilized by the individual fire manager and may be an expectation of a state-wide 

smoke management program or employed to maintain the social acceptability of using prescribed fire 

and managing air quality impacts of smoke. 

Table 1. Summary of Basic Smoke Management Practices (BSMPs), benefit achieved with the BSMP, and 

when it is applied (before, during or after the burn).

Basic Smoke 

Management Practice

Benefit achieved with the BSMP When the BSMP is Applied –

Before/During/After the Burn

Evaluate Smoke 

Dispersion Conditions

Minimize smoke impacts Before, During, After

Monitor Effects on Air 

Quality

Be aware of where the smoke is going and 

degree it impacts air quality

Before, During, After

RecordKeeping/Maintain a 

Burn/Smoke Journal

Retain information about the weather, burn 

and smoke. If air quality problems occur, 

documentation helps analyze and address air 

regulatory issues

Before, During, After

Communication –

Public Notification

Notify neighbors and those potentially 

impacted by smoke, especially sensitive 

receptors

Before, During

Consider Emission 

Reduction Techniques

Reducing emissions can reduce downwind 

impacts

Before, During
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Share the Airshed –

Coordination of Area 

Burning

Coordinate multiple burns in the area to 

manage exposure of the public to smoke

Before, During, After

BSMP #1: Evaluate smoke dispersion conditions to minimize smoke impacts

There are many ways to evaluate smoke dispersion conditions such as identifying smoke sensitive 

receptors, smoke modeling to determine where smoke may go and degree of impact, and most 

importantly use of readily available meteorological forecasting of conditions that influence smoke 

dispersion. Based on all this information, adjustments can be made as necessary to ignition date/time, 

firing sequence, and post-burn mop-up procedures, etc. The Appendix gives information about the type 

of meteorological information that may be available in your area and atmospheric parameters that 

influence smoke dispersion, such as: wind speed (near the surface and aloft), wind direction, mixing 

height, ventilation index, atmospheric stability, vertical temperature profile of the atmosphere and 

inversions, and water vapor (both in the atmosphere or released from the fire).

Prior to burning it is important to identify smoke sensitive areas downwind of burn areas such as 

highways, communities, airports, scenic vistas, Class 1 visibility protection areas, air quality 

nonattainment areas (see page 8), etc. Fire managers should then determine meteorological conditions 

including wind speed, direction and mixing height that will promote smoke dispersal away from 

sensitive areas and prevent ground level smoke accumulations. Burning should be avoided when mixing 

heights are low or a temperature inversion exists (see the Appendix for more information).

During burn operations

• (Critical) Fire managers should obtain and 

use the most up-to-date meteorological 

forecast (National Weather Service (NWS, 

http://radar.srh.noaa.gov/fire/) Spot Fire 

Weather Forecast or other data source), to 

inform whether to ignite a burn or not and to 

time ignitions to maximize dispersion away 

from sensitive areas.

• Where possible, obtain and use air quality 

forecasts such as AirNOW (http://www.airnow.gov) for your area and downwind to help time 

ignition to avoid periods when air quality is expected to be exceeding, or close to exceeding, the 

National Ambient Air Quality Standards (NAAQS). Nearby air quality monitoring sites may also 

be assessed to verify current air quality conditions. 

• Verify the forecasted weather conditions whenever possible with local observations such as 

from Remote Automated Weather Stations (RAWS), and on-site or nearby weather monitoring 

sites. Small test burns or use of pilot balloons (which give wind speed and wind direction 

information vertically in the atmosphere) are also a means of getting an idea of both potential 

fire behavior and smoke dispersion.

After burn operations smoke can continue to be generated from smoldering fuels such as piles, large 

down trees/stumps, and in some areas of the country the organic duff layer. Meteorological and 

topographical features can keep the smoke near the surface and transport it along drainages, especially 

during the nighttime hours (see the Appendix). This should be assessed for potential impacts to smoke 

sensitive receptors and especially roads and post burn mop-up procedures may be needed to extinguish 

smoldering fuels.
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Simple Smoke Screening Tool – Recommended

(http://shrmc.ggy.uga.edu/maps/screen.html) 

The online simple smoke screening tool is a simple, 

easy-to-use application that relies on google maps and 

the methodology laid out in the Southern Forestry 

Smoke Management Guide 

(http://www.srs.fs.usda.gov/pubs/viewpub.php?index

=683, Figure (A)) to highlight the critical smoke impact 

area (shown in red, Figure (B)) and the smoke impact 

area of concern (shown in yellow, Figure (B)) 

downwind from a fire. This tool was developed and is 

hosted online by the Forest Service Southern Research 

Station. By entering information about fire location, 

acres to burn, fuel type (grass, shrubs, litter, slash), ignition method (backing fire, heading fire), and 

wind direction, the application will identify the potential downwind smoke impact area. Zoom and pan 

capabilities, used to identify smoke sensitive receptors such as towns, highways, schools, etc., are 

provided with this google map application. Actual ground level impact will vary based on mixing height 

and other meteorological conditions and topographical elements influencing the burn (see the 

Appendix), but the tool provides an excellent first step in understanding potential levels of smoke 

impacts from a proposed burn. Use of this tool is highly recommended. 

(A)

(B) 
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BSMP #2: Monitor the effects of the 

fire on air quality 

Monitoring the effects of fire on air 

quality can include keeping track of 

where the smoke goes, how high it 

goes and whether it disperses well or 

is tight and dense, which can be done 

through visual monitoring and can be 

documented by notes, photographs, 

aircraft observations, satellite 

imagery, air quality monitoring data, 

and post-burn evaluations. The air 

quality in the vicinity of sensitive 

receptors such as towns, highways, 

schools, etc. is of particular 

importance to monitor.

Before igniting, assessing the air 

quality conditions is a good way to 

avoid making a condition worse. 

Utilize the AIRNOW forecast for your 

area and assess current air quality 

conditions by checking local and 

downwind air quality monitors when 

available. 

To give an idea of how smoky 

conditions can correlate with visible 

range, Figures A and B are shown 

here. They are examples from a 

smoke photo series under 

development by the US Forest Service

in cooperation with the National Park Service (NPS). Figure A shows a non-smoky atmosphere and how 

visible a point 2.6 miles away is, while Figure B shows the same view but under smoky conditions and 

the affect on visible range. The reduction in visible range typically indicates the degree of impact of 

pollution. When evaluating smoke effects on visible range it is important to take into account relative 

humidity and the presence of urban/anthropogenic pollution – a given visual range for northern 

California (as shown here) could be very different in the southeastern US which has much higher 

humidity (See the Appendix Water Vapor Section). In situations with smoke and high relative humidity 

white-out conditions can occur which can be of particular concern for roadways. For judging the 

severity of air quality impacts, the air quality index provides a scale from “good” for clean air to 

“hazardous” for extremely polluted situations. See http://airnow.gov/index.cfm?action=aqibasics.aqi

for more information.

(A)

(B)
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BSMP #3: Record-keeping of BSMP’s, fire activity, and smoke behavior

Record-keeping can be as simple as keeping a personal burn/smoke journal. Having a record of the 

weather, BSMPs applied on the burn, the fire activity (fuels, area burned, ignition time, etc.) and smoke 

behavior can be used to help assess the conditions and burns that meet goals, and provide lessons 

learned if goals were not met to expectation or if there were smoke problems identified at downwind 

receptors (for example, did smoke cause hazardous conditions across a road?). In cases where air 

quality monitoring data exceed national and/or local standards, and if the state decides to seek to 

remove the data from the monitoring record, then documentation of BSMPs are critical. In these cases

the state may not seek such documentation until several years after the event. Record-keeping should 

document the BSMPs used and include: notes on weather forecast and conditions both during and after 

the burn which influenced the dispersion of smoke, acres treated, location, date, and time of the burn,

how much and what was burned (fuels information), and noting smoke impacts if any. This 

documentation should be retained by the fire manager long enough to meet regulatory time frames. 

BSMP #4: Communication – Public Notification

Fire managers need to notify appropriate 

authorities and those potentially affected by the 

smoke including the public at sensitive 

receptors. In addition, it is useful to prepare for 

contingency actions during the fire to reduce 

exposure of people at such receptors if an 

unintended impact were to occur. 

Routine procedures should be established to 

notify the public of the burn (especially sensitive 

populations and appropriate authorities such as 

air regulators, public health officials and local 

fire department). As a contingency measure

during the burn, notification of these same parties and appropriate air quality and/or county health 

authority should occur if there is an unintended smoke impact. Fire mangers should consider fire 

management and suppression options such as mop-up or cutting off a burn to minimize such an impact. 

BSMP #5: Consider use of emission reduction 

techniques (ERTs)

There are several methods for reducing emissions that 

can be considered when planning and conducting a 

burn. Care should be taken to ensure the methods 

chosen actually reduce the amount of total emissions 

over time, not just delay them. Some ERTs can also 

reduce plume rise and could increase surface smoke

concentrations. It is recommended that documentation 

be kept on the use of ERTs and where possible a 

quantification of emissions averted for air quality 

regulatory purposes. Key ERTs include reducing the fuel 

load and burning the minimum material to meet objectives, reducing fuel burned (for example, burn 

only the area needed and prevent the fire from spreading, extinguish the smoldering burns, burn prior 

to precipitation, or burn before litter falls), and increasing burning efficiency (for example, allow the 
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material to dry before burning, minimize soil content in slash piles, burn in piles, or use a backing fire 

when grass is burned).

Identify and document appropriate NRCS conservation practices that can help reduce emissions, such 

as: Brush Management, Clearing and Snagging, Firebreak, Forest Stand Improvement, Fuel Break, 

Prescribed Grazing, and Woody Residue Treatment.

For more information on emission reduction techniques see The Smoke Management Guide for 

Prescribed and Wildland Fire, 2001 edition (http://www.treesearch.fs.fed.us/pubs/5388) and the 

Western Regional Air Partnership Fire Emissions Joint Forum document on ERTs at: 

http://www.wrapair.org/forums/fejf/documents/ert/index.html

BSMP #6: Share the airshed/air basin to minimize 

exposure of the public – Coordination of Area Burning

Develop a communications and information-sharing 

network among fire managers who may be in the burn 

vicinity on the same day or who could cumulatively impact 

an area or sensitive receptor. This enables coordination and 

planning of ignitions to cooperatively limit burning so as not 

to overwhelm the ability of the atmosphere to disperse the 

smoke from burns and minimize exposure of the public. 

This also helps prevent contributing to cumulative or 

adverse downwind impacts from smoke. Determining air 

quality conditions before ignition takes place should be a 

consideration for coordination. Air quality information can be obtained from the EPA AIRNOW website 

(http://www.airnow.gov) or from local/state air quality monitoring networks or agencies. The National 

Oceanic Atmospheric Administration (NOAA) Hazard Mapping System (HMS) analyzes satellite fire 

detections from multiple satellites to present a view of current fire hot-spots and satellite-visible smoke 

plumes across North America (http://www.osdpd.noaa.gov/ml/land/hms.html). This can give 

information about other burning occurring across the region. 

RELATED TOPICS AND TRAINING

Air Quality and Atmospheric Change in NRCS

NRCS has four Air Quality and Atmospheric Change (AQAC) resource concerns: Odor, Particulate Matter, 

Ozone Precursors and Greenhouse Gasses. Four online courses have been developed that are available 

through AgLearn, they are: Air Quality, Climate Change and Energy; Why Should we Care About Air 

Quality?; Air Quality Resource Concerns; and Greenhouse Gasses and Carbon Sequestration. To learn 

more about AQAC issues within the agency and to access the online courses, visit the AQAC website at 

http://www.airquality.nrcs.usda.gov.

Smoke and the Clean Air Act

BSMPs can protect the public from smoke exposure, help avoid an exceedance of a National Ambient Air 

Quality Standard (NAAQS) and minimize impacts on sensitive areas such as Class 1 visibility areas. There 

are six criteria pollutants regulated under the clean air act; particulate matter, ozone, nitrogen dioxide, 

sulfur dioxide, carbon monoxide and lead. With regards to fire, particulate matter and ozone are of 

concern, and near the fire carbon monoxide can be a concern as well. When concentrations of a criteria 

pollutant are measured above the level of the standard for the particular pollutant, then an area can be 
Basic Smoke Management Practices

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determined to be in nonattainment of the standard and subject to controls as delineated in a State 

Implementation Plan (SIP). The Exceptional Event Rule (e.g. “EPA 40 CFR Parts 50 and 51 Treatment of 

Data Influenced by Exceptional Events”) affords the states protection from being put into nonattainment 

for events that are not controllable. Such events can be natural (ex. wildfires) or due to other reasons 

including prescribed fires. Documented use of BSMPs can allow for a state to flag data and seek 

exclusion for an exceedance of the NAAQS if appropriate Exceptional Event Rule (EER) criteria are met. 

BSMPs can also be considered as smoke management techniques as cited in the Regional Haze Rule 

(RHR) and therefore used to address pollution that causes visibility impairment in Class I areas; 

approximately 156 national parks and wilderness areas across the US. Fire managers can learn more 

about this by taking the approximately one hour online course “Smoke Management and Air Quality 

for Land Managers” available at: http://www.cnr.uidaho.edu/smoc/. 

National Coordination on Smoke Issues

The National Wildfire Coordinating Group (NWCG) Smoke Committee (SmoC) has been 

established to provide interagency leadership, coordination and integration of air resource 

and fire management objectives to support overall land management goals. Members are 

from the Bureau of Land Management, Fish & Wildlife Service, National Park Service, Bureau of Indian 

Affairs, USDA Forest Service, and the National Association of State Foresters (eastern and western 

representatives), as well as the Natural Resources Conservation Service, the National Association of 

Clean Air Agencies (NACAA), The Nature Conservancy (TNC), and Department of Defense (DoD). SmoC 

has three Subcommittees; The Smoke Managers Subcommittee which works to provide relevant 

technical, administrative, and organizational information and feedback for operational smoke managers, 

forecasters and modelers; The Technical Smoke Topics Subcommittee which addresses technical smoke 

issues; and The Training subcommittee which works to advance training in smoke and air quality topics 

for the wildland fire community. More information is available on the public MyFireCommunity “Air 

Quality and Fire Issues” neighborhood at: 

http://www.myfirecommunity.net/Neighborhood.aspx?ID=279

Authors: Susan O’Neill (NRCS), Pete Lahm (US 

Forest Service), Anthony Mathews (US Forest 

Service).

Attribution: The information provided in this 

document is based on discussions between Forest 

Service, NRCS, and Department of Interior 

prescribed fire practitioners, smoke management 

specialists, and air quality program personnel.

Contact – US Forest Service

Pete Lahm, Air Resource Specialist, 

plahm@fs.fed.us, pete.lahm@gmail.com, 202-205-1084.

Contact – NRCS 

Pat Shaver, Rangeland Specialist, pat.shaver@por.usda.gov, 503-273-2407.

Chuck Stanley, Rangeland Specialist, charles.stanley@ftw.usda.gov, 817-509-3282.

Susan O’Neill, Air Quality Scientist, susan.oneill@por.usda.gov, 503-273-2438.
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REFERENCES

2001 Smoke Management Guide for Prescribed and Wildland Fire. Editors C. Hardy, R.D. Ottmar, J.L. 

Peterson, J.E. Core, and P. Seamon. Produced by the National Wildfire Coordinating Group Fire Use 

Working Team. PMS-420-2. http://www.treesearch.fs.fed.us/pubs/5388

Achtemeier, G.L. (2003). On the origins of "superfog" -a combination of smoke and water vapor that 

produces zero visibility over roadways . In: Second International Wildland Fire Ecology And Fire

National Smoke Management Website: http://www.nifc.gov/smoke

Southern Forestry Smoke Management Guide: 

http://www.srs.fs.usda.gov/pubs/viewpub.php?index=683

Turner, D.B. (1994). Workbook of Atmospheric Dispersion Estimates. An Introduction to Dispersion 

Modeling. Second Edition. CRC Press. ISBN 1-56670-023-X.

Wade, D., and H. Mobley (2007). Managing Smoke at the Wildland-Urban Interface. USDA Forest 

Service Southern Research Station. General Technical Report SRS-103.

Western Regional Air Partnership Fire Emissions Joint Forum document on ERTs at: 

http://www.wrapair.org/forums/fejf/documents/ert/index.html

Whiteman, C.D. (2000). Mountain Meteorology Fundamentals and Applications. Oxford University 

Press. ISBN 0-19-513271-8
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APPENDIX – Meteorological Parameters for Smoke Dispersion

This appendix discusses meteorological parameters applicable to smoke dispersion. Many of these 

parameters may be available from local forecasts. Check with your local National Weather Service

office, air quality regulatory department, or other public land management agencies in the area.

Wind Speed and Direction

Wind speed and direction can play an important role in the dispersion of smoke and the location of 

potential smoke impacts. Wind speed will help disperse a plume; however, strong surface wind speeds 

will also cause a plume to lay-down near the surface and inhibit vertical dispersion. Surface drag will 

reduce winds at the surface, then winds will gradually increase with height away from the surface 

causing the smoke to disperse differently (slower) at the surface than aloft which can be important 

when considering a backing versus heading fire. Wind direction at the surface can also be very different 

than wind direction aloft. Thus, depending on smoke impact concerns, whether concerned about 

nearby sensitive receptors or receptors further downwind, both parameters should be noted. 

Topography can particularly influence the wind direction of surface winds as well, where winds may flow 

along a valley near the surface but be quite different aloft (away from the topographical influences). In 

valleys, there can be downslope flows due to surface cooling in the evening which is important if 

smoke is still being produced after dark and the drainage crosses a road. Similarly, in the morning 

there can be upslope flows from the valley with surface heating. All these factors are important for 

smoke dispersion.

Mixing Height

The mixing height is the height of the atmosphere above the ground which is well mixed due either to 

mechanical turbulence or convective turbulence. The air layer above this height is stable. The mixing 

height defines the depth of the mixed layer. Smoke released into the atmosphere has the potential to 

disperse vertically in the atmosphere up to the height of the mixing height depending on wind speed 

and atmospheric stability. A low mixing height can limit how the smoke disperses and can lead to 

greater smoke concentrations near the ground for longer periods of time.

Ventilation Index (VENT)

Ventilation Index (VENT) is typically the product of the mixing height and the transport wind speed. The

transport wind speed is typically the average wind speed through the mixed layer. By combining the 

two parameters of mixing height and transport wind into one Index, the dispersive potential of the 

atmosphere can be rated. Care should be taken to note when transport winds are high and mixing 

height is low because these conditions will keep smoke traveling close and confined to the surface. 

Conversely, when transport winds are low but mixing height is high, the smoke will loft high into the 

atmosphere (good dispersion) but fire behavior could be erratic and thus problematic. A single national 

scale does not exist for the ventilation or dispersion index so investigate your local implementation of 

this parameter. 
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Atmospheric Stability

Atmospheric stability is a measure of the 

atmosphere's tendency to encourage or deter 

vertical motion. In unstable conditions, a lifted 

parcel of air will be warmer than the surrounding 

air at altitude. Because it is warmer, it is less dense 

and will continue to rise. Figure (A) is an example 

of smoke behavior in an unstable atmosphere –

smoke is lofted away from the ground and 

transported downwind by the upper level winds. 

In a stable atmosphere the temperature of a rising 

parcel of air becomes cooler than its surroundings 

causing it to sink back to the surface, thus vertical 

motion is limited and smoke will tend to stay close 

to the surface. Figure (B) is an example of a stable 

atmosphere where smoke is fumigating the area 

beneath the mixing height and most vertical motion 

is due to the heat of the fire itself. Atmospheric 

stability can be estimated based on wind speed and 

solar insolation (Turner, 1994) on a scale of A (very 

unstable) to D (neutral) to F (very stable). Often 

the local NWS fire weather forecast will provide an 

estimation of atmospheric stability. (photos by Roger Ottmar, USFS)

Atmospheric Vertical Temperature Profile and Inversions

The vertical temperature profile of the atmosphere is also related to atmospheric stability. On most 

days, the temperature of air in the atmosphere decreases with altitude. This is because most of the 

sun’s energy is converted to sensible heat at the ground, which in turn warms the air at the surface. The 

warm air rises in the atmosphere, where it expands (due to lower pressure aloft) and cools. Sometimes, 

however, the temperature of air actually increases with height. The situation of having warm air on top 

of cooler air is referred to as a temperature inversion, because the temperature profile of the 

atmosphere is "inverted" from its usual state. There are two types of temperature inversions: surface 

inversions (Figure A) that occur near the Earth's surface, and aloft inversions (Figure B) that occur higher 

in the atmosphere. Figures used by permission from Whiteman (2000).

(A)

(B)

(A) (B)
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The most common manner in which surface inversions form is through the cooling of the air near the 

ground at night. Once the sun goes down, the ground loses heat very quickly, and this cools the air that 

is in contact with the ground. However, since air is a very poor conductor of heat, the air just above the 

surface remains warm. Conditions that favor the development of a strong surface inversion are calm 

winds, clear skies and long nights. Calm winds prevent warmer air above the surface from mixing down 

to the ground, and clear skies increase the rate of cooling at the Earth's surface. Long nights allow for 

the cooling of the ground to continue over a longer period of time, resulting in a greater temperature 

decrease at the surface. Since the nights in the wintertime are much longer than nights during the 

summertime, surface inversions are stronger and more common during the winter months. A strong 

inversion implies a substantial temperature difference exists between the cool surface air and the 

warmer air aloft. During the daylight hours, surface inversions normally weaken and disappear as the 

sun warms the Earth's surface. However, under certain meteorological conditions, such as strong high 

pressure over the area, these inversions can persist as long as several days. In addition, local 

topographical features can enhance the formation of inversions, especially in valley locations. Adapted 

from: http://www.wrh.noaa.gov/slc/climate/TemperatureInversions.php

Surface temperature inversions play a major role in how smoke disperses and in air quality conditions in 

general. The warm air above cooler air acts like a lid, suppressing vertical mixing and trapping the cooler 

air at the surface. If smoke is emitted into these conditions or is transported and trapped in the 

inversion then this can lead to poor air quality conditions. Care should be taken when burning during 

inversions or when one is expected to setup. Nighttime inversions can burn-off during the day 

therefore, depending on burn objectives and forecasted conditions, ignition during an inversion can be 

undertaken with caution and close monitoring. Also, if an inversion is expected to setup quickly postburn (such as at night), it has the potential to trap smoke, and mitigation techniques such as mop-up can 

be employed to reduce the longer-term smoldering. In complex terrain, burning on slopes above an 

inversion can keep the smoke aloft and away from the valley floor (where roadways and communities 

are often located), but again, this should be undertaken with caution and close monitoring. Persistent 

(multiple-day) inversions in particular can create poor air quality conditions and burning under such 

conditions is not recommended. 

Water Vapor – Water Released from Fire and Atmospheric 

Water Content

As fuel is heated and combusted, water vapor is released into the 

atmosphere. This water can condense onto fine particulate 

matter from the fire and from other sources of pollution, 

reducing visibility and can play a role in the in-plume chemistry of 

secondary organic aerosol production. Where ambient 

atmospheric humidity can be high, a common situation in the 

Southeast US but possible across the country, the addition of 

water vapor from fire to the atmosphere, combined with

nighttime cooling and inversions, can cause the atmosphere to 

become saturated (or nearly saturated). As temperatures 

decrease in the evening and especially early morning hours, the 

water vapor will condense out of the atmosphere onto the fine 

particulate matter released from the fire. This can quickly 

create a thick white out fog (“superfog”) that pools in low-lying areas reducing visibility to near zero. 

This phenomena and has been attributed to numerous traffic accidents (Achtemeier, 2003, Wade and 

Mobley, 2007). The Low Visibility Occurrence Risk Index (LVORI, Lavdas and Achtemeier, 1995) was 
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developed based on relative humidity and the smoke dispersion index to be an indicator of potential fog 

occurrence. Values range from 1 - 10, where a LVORI of one means there is almost no chance of low 

visibility, and a LVORI of ten indicates low visibility is likely. For more information see: 

http://www.erh.noaa.gov/gsp/fire/ADI_LVORI/ADI_LVORI.html

National Weather Service (NWS) Fire Weather Information (http://radar.srh.noaa.gov/fire/): The 

National Weather Service Fire Weather webpage is a portal to local meteorological forecasts and 

observational data regarding many of the meteorological parameters discussed above. Below is an 

example of a NWS fire weather forecast for an area in Texas. In this case, information is given for near 

surface winds, cloud cover, transport winds, ventilation index and the category smoke dispersion day. 

The category day is based on the ventilation index and is on a scale of 1 to 5 where 1 is poor dispersion 

and 5 is excellent dispersion. Local/regional NWS offices typically customize the information to meet 

the needs of the area and can also do special spot forecasts. Use of these forecasts is a critical BSMP 

element.

Smoke Modeling

Smoke models provide a means of using meteorological and fuels information to give more detailed 

information about where and how smoke could disperse and the concentration of PM and other trace 

gases in the plume. A smoke modeling system essentially takes into account all the meteorological 

parameters described above along with on the ground fuels information to predict smoke dispersion, 

transport, and in some cases the trace gas chemical reactions. Smoke modeling is a more advanced 

feature that will be described in another Technical Note. Smoke modeling options are also summarized 

at: http://www.nifc.gov/smoke.