Environmental Impacts of Wildfires

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Environmental Impacts of Wildfires

• Shelly Miller
• Mike Hannigan
• Jana Milford
• Mike Kleeman
• David Henderson
• Mike Robert

CU Mechanical Engineering Graduate Student
Seminar Fall 2002
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Fuel
compound class of dry weight
amino acids 0.6
nucleic acids 0.2
proteins 7.6
carbohydrates 38
monosaccharides 1.9
sucrose 3.1
cellulose 21
hemicellulose 9.8
pectin 1.9
lipids 5.3
fatty acids 4.0
glycerols 0.3
other 1.0
lignin 23
phenolics 20
organic acids 3.5
minerals 1.5
Molecular composition of a pine tree.
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complete combustion products
Globally, CO2 emission from wildfires are 2-5
Pg/yr which is 30-80 of fossil fuel CO2 emission
estimates.
CO2, H2O, and heat
CO2 emission rates measured in the plumes of
wildfires range from 1.3-1.8 kg CO2 per kg fuel.
CO2 is removed by reaction with OH (very slow) or
by gradual partitioning into water drops that are
rained out.
The heat does work by making the plume rise.
Thus, the heat is lost relatively quickly.
Heat has only local effect.
H2O has local/regional effect.
CO2 has global effect.
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incomplete combustion products

• Cause
• Lack of oxygen.
• Complex fuels.
• Poor heat transfer.

Globally, CO emissions from wildfires account
from 10 to 50 of total CO emissions.
Nitrogen is key component of the nutrient
cycle. Reduced nitrogen emitted from biomass
burning is causing global redistribution of
nitrogen. (from mostly tropical to global)
trace gases CO, CH4, hydrocarbons, NOx, NH3, HCN,
organic N VOCs acetaldehyde, acetone, methanol,
vinyl acetate, particles soot, minerals,
organic mixtures
CH4 is also a greenhouse gas, actually more
efficient than CO2. Wildfire emissions account
for 25 to almost all the total global CH4
emissions.
Just as in urban areas, NOx and hydrocarbons (HC)
react to form ozone. Due to biomass burning, O3
in the tropics is 30 greater than background
CO emission rates vary with combustion condition,
ranging from 5 to 25 of CO2 emissions.
CH4 is very stable and only removed via oxidation
by OH or O3. CH4 is global.
CO and CO2 have similar removal mechanisms,
except OH CO is much faster. CO/CO2 ratios
decrease slowly as a plume ages. Still, CO
emissions have a large spatial scale effect.
CO CO2 emission account for 85 to 99 of
wildfire carbon emissions.
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What matters size and composition and amount
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Particle Composition
Reported emission rates of levoglucosan from
biomass combustion range from 2-12 of the
particle mass.
Other anhydrous sugars have been seen that
correspond to constituents of hemicellulose and
pectin, but not to the same degree.
Lignin pyrolysis products also abound.

• Prominent metals
• Potassium
• Sulfur
• Chlorine

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Terpenoids
Terpenoids are polymers with commonality of the
same basic unit isoprene.

• Functionally and chemically diverse group of
  plant compounds.
• Hormones
• Oils and resins
• Pigments
• Sterols

During wildfires, these terpenoids can be
pyrolyzed and the products emitted or they can be
directly emitted by volatilization.
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Size and Composition
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Research Objectives

• Measure residential indoor and outdoor PM2.5
  (particulate matter smaller than 2.5 ?m) while
  wildfire smoke is present

• Determine the effectiveness of recommended indoor
  exposure mitigation measures
• Keeping windows closed
• Using portable air cleaners

Photo by Bryan Day, Idaho, 2000
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History and Future of Fire

• In the 1930s, 39 million acres burned naturally
  per year
• In the1980s 4.2 million acres burned per year
  (NIFS 2002)
• Cost of a prescribed burn 75/acre
• Cost of a wildfire 1000/acre (USFS 2002)

• Currently, the annual target for prescribed burns
  by 2005 is greater than 5 million acres (OAR
  1998), compared to fewer than 700,000 acres
  burned from 19841994 (APCD 2000)

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PM Measurements near Fires

• In Hoopa Valley, CA 1999 PM10 levels exceeded 350
  ?g/m3 for over a week and exceeded the EPAs
  hazardous levels of 425 ?g/m3 for two days (Mott
  2001)
• In Hamilton, MT 2000 PM10 levels of 300600 ?g/m3
  were experienced during multiple days and during
  a 1-h period concentrations exceeded 999 ?g/m3
  (Acheson, 2001 Ward and Smith, 2001)
• In Indonesia, 1997 a 2-mo period of uncontrolled
  wildfires produced total suspended particles
  levels up to 15 times the established limit of
  260 ?g/m3 (WHO, 1999).

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Health Effects

• Significant associations between outdoor PM
  concentrations during fires and health effects
  are
• increased hospitalization and visits to emergency
  room
• increased respiratory symptoms
• exacerbation of asthma
• decreased lung function
• These impacts have been observed primarily in the
  elderly, the very young and in individuals with
  pre-existing respiratory and/or cardiovascular
  illness (WHO, 1999 Mott 2001)

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Experimental Design

• Test the effectiveness of keeping windows closed
  and air cleaner operation on the indoor air
  quality

• Locate wildfire producing smoke that will impact
  local residents
• Identify and recruit two homes to be studied
• Install air cleaners in one of the 2 homes

• Monitor indoor and outdoor PM2.5 concentrations
  at both homes during fire

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Recruitment Methods

• Fire located by monitoring local news and then
  contacting local forest service for hourly
  updates
• When smoke would impact a populated location,
  equipment quickly loaded and taken to the area
• Local fire department contacted for 2 sets of
  volunteers and CDPHE provided 2 sets
• Homes of similar construction and age
• Residents all nonsmokers and wood burning stoves
  not used
• Residents told to keep all windows and doors shut
  and to record any activities which may introduce
  PM into the indoor environment
• 2-3 air cleaners placed in one of the residence

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Measurements

• Indoor and outdoor 24-h average PM2.5 mass
  concentrations using Harvard impactors
• Real-time indoor and outdoor particle
  concentrations lt0.5 ?m for 24 h using Climet
  optical particle counters
• Air-exchange rate using CO2 tracer gas decay
  method

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Air Cleaners
Friedrich C-90a Electrostatic Precipitator

• PRE-FILTER catches larger particles
• IONIZING CELL electrically charges particles when
  they pass through a powerful electric field
• COLLECTOR PLATES immediately attract "charged"
  particles
• ACTIVATED CARBON FILTER removes most common odors
  and fumes

• 3 tests performed on the air cleaners in a test
  chamber to measure Clean Air Delivery Rate (CADR)
• We measured an average CADR of 420 m3/ h
• Agrees with CADR of 325-370 m3/ h that is
  published by Association of Home Appliance
  Manufacturers

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The Fires

• Polhemus prescribed burn Burned all October 2001,
  producing heavy smoke on several days. Monitoring
  took place 10/20/01 to 10/21/01 when 2500 acres
  were ignited. Houses 1 and 2 were located 24 and
  27 km north of this fire
• Schonover wildfireStarted by lightning on
  5/21/02 and quickly grew to 2000 acres. Houses 5
  and 6 were both located 24 km north of the fire.
  Monitoring took place 5/22/02 to 5/23/02.
  Ultimately the fire consumed 3800 acres and cost
  2.4 million dollars to fight

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Schoonover fire 5/23/02 (NOAA)
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The Fires
4/24/02 530 PM 1800 acres (NOAA)

• The Snaking wildfireBegan 4/23/02 behind Platt
  Canon High School. By 4/28/02 the fire consumed
  2590 acres. Monitoring took place 4/25-4/26 11
  km east of the fire.

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Snaking wildfire 11 15 am- 330 pm (MST) 4/24/02
(NOAA)
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The Biggest Wildfire in Colorado Recorded
History!!!
The Hayman wildfire 6/10/02 (NOAA) 11am-5pm.
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The Fires

• The Hayman wildfire
• Began 6/8/02, contained 7/2/02
• Consumed 137,760 total acres (67,700 in first
  two days), 133 residences, 1 commercial building,
  466 out-buildings
• Sampling during this fire was difficult because
  the smoke plume was energetic enough to rise to
  the upper atmosphere
• Sampling took place on 6/10/02 with no results
• A second trip was planned on 6/18/02. There was
  smoke impact the previous day in Denver. Similar
  atmospheric conditions were forecasted. Two
  houses were located in southern Denver located 47
  km from the fire. This day was successful.

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Colorado fires on 6/9/02 703 pm (NOAA)
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Data Analysis
Impact of air cleaners
Impact of windows closed
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Polhemus Prescribed Burn 24-h average PM2.5
(?g/m3)
Concentration in house 2 was 83 lower than in
house 1 I/O ratio in house 1 was 50 lower than
background I/O ratio
Windows closed
Error bars data range
2 air cleaners
Cooking event
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Polhemus Particle Counts
House 1 OPC, number of particles 0.5-5.0 ?/m3
Model assumes V815 m3, ?0.21 h-1
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Snaking Wildfire

• Measurements were made on two consecutive days in
  houses 3 and 4, May 25 and 26 2002
• On May 25th air cleaners were installed in house
  4
• PM2.5 concentration in house 4 was 80 lower than
  in house 3 on May 25th
• On May 26th air cleaners were moved to house 3
• On May 26th, house 3 was 62 lower than house 4

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Snaking Wildfire 2-day Comparison
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Hayman Wildfire24-h average PM2.5 (?g/m3)
Concentration in house 9 was 87 lower than in
house 10 I/O ratio in house 10 was 21 lower than
background I/O ratio
Windows closed
3 air cleaners installed
Error bars data range
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Hayman Wildfire Particle Counts
House 9 OPC, number of particles 0.5-5.0 ?/m3
Model assumes ?0.17 h-1, V510m3 3 air
cleaners installed total CADR 1260 m3h-1
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Indoor PM2.5 Increases during Fires in Homes
without Air Cleaners
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Air Cleaners Reduce Indoor PM2.5 during Fires
Results are valid, because homes have similar air
exchange rates and indoor/outdoor background
measurements
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Keeping Windows Closed during Fires Reduces PM2.5
in Homes without Air Cleaners
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Summary

• Wildfires and prescribed burns caused an increase
  in indoor PM2.5
• Indoor levels increase to 57-100 of outdoor
  concentrations when windows are closed
• Air cleaners reduced indoor air PM2.5 by an
  average of 80 when compared to homes without air
  cleaners
• Closed windows provided 18-50 reduction of
  indoor PM2.5 when compared to background
• Indoor and outdoor background measurements were
  all similar and range between 3-5 ?g/m3.

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Acknowledgments

• US EPA Region 8
• Funding
• US EPA Radiation and Indoor Environment Lab
• Tri-county Health Department
• Sampling Equipment
• CDPHE
• Gravimetric filter analysis
• (Colleen Cambell) Information on weather, smoke
  movement, and access to volunteers
• Boulder Fire Department, US Forest Service
• Data on wildfires, and access to volunteers

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Thank You!