environmental impacts of wildfires shelly miller mike hannigan jana milford mike kleeman david...
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Environmental Impacts of Wildfires
Shelly MillerMike Hannigan
Jana MilfordMike Kleeman
David HendersonMike Robert
CU Mechanical Engineering Graduate Student SeminarFall 2002
Fuelcompound 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.
The “glue” is a heterogeneous polymer termed lignin.
After a cell stops growing, the cell creates a secondary wall which gives the plant it’s rigid structure. To the right is a depiction of this secondary wall, minus the “glue” that fills the empty space. This “glue” gives wood it’s strength.
Lignin monomers
carbohydrate base
During the growth stage, all plant cells form only a primary cell wall.
The cell wall is composed exclusively of cellulose.
Cellulose is a linear polymer of glucose, which is a C6 carbohydrate (a.k.a., sugar).
litter
Litter is preferentially composed of leaves and needles, which have less cell wall per unit mass and more surface area per unit mass. Plant surfaces are composed of the cuticle, which is a heterogeneous polymer of fatty acids, phenolics, long chain alcohols, fatty acid derivatives and odd-numbered n-alkanes. In addition, the N:C ratio is higher in leaves and needles so the ground fuel will have a relative emission of N.
duff
Duff has a higher percentage of the more stable plant components, such as metals.
humus
Humus is more homogenous and has even higher ratios of metals.
complete combustion products
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2 CO2
CO2
H2O
H2O
H2OH2O
H2O
H2O
H2O
heat
heat
heat
CO2, H2O, and heat
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.
H2O
H2O
H2O
H2O
In the plume, the H2O vapor cools as the heat
is lost. Some of this H2O will condense and
grow rain drops.
CO2 is removed by reaction with OH (very slow) or by
gradual partitioning into water drops that are rained out.
CO2 has global effect.
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2
CO2CO2
CO2CO2
CO2 emission rates measured in the plumes of
wildfires range from1.3-1.8 kg CO2 per kg fuel.
Globally, CO2 emission from wildfires are 2-5 Pg/yr which is 30-80% of fossil
fuel CO2 emission estimates.
incomplete combustion products
trace gasesCO, CH4, hydrocarbons, NOx, NH3, HCN, organic N
VOCsacetaldehyde, acetone, methanol, vinyl acetate, …
particlessoot, minerals, organic mixtures
Cause:• Lack of oxygen.• Complex fuels.• Poor heat transfer.
CO emission rates vary with combustion condition, ranging from 5 to 25% of
CO2 emissions.
CO + CO2 emission account for 85 to 99% of wildfire carbon emissions.
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.
Globally, CO emissions from wildfires account from
10 to 50% of total CO emissions.
COCO
CO
CO
CO
CO
CO
CO
CO
CO
CH4
CH4
CH4
CH4
CH4 is also a greenhouse gas, actually more efficient than CO2.Wildfire emissions account for
25% to almost all the total global CH4 emissions.
CH4 is very stable and only removed via oxidation by OH or O3.
CH4 is global.
HC
HC
HC
NOx
NOx
NOx
O3
O3
O3
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
reduced N
reduced N
reduced N
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)
CO
othe
r in
com
plet
eco
mbu
stio
n pr
oduc
ts
Fine particles
Mor
talit
y ris
k
6 cities study
6 cities study looked at acute effect of exposure. More recently, researchers have
seen correlations with fine particle levels and mortality for chronic exposure.
flaming
smoldering
total particle mass emission rate
soot
mas
s em
issi
on r
ate
particles
incomplete combustion products
Water drops come from condensing water vapor onto particle. We call the particles cloud condensation nuclei (CCN). A particles ability to act as
CCN depends on the composition and size. The more CCN, then more cloud drops per cloud. The more cloud drops per cloud, the more the
cloud scatters light. This will change the earth’s energy budget.
Soot (black or light absorbing particles) are not excellent CCN; however, they still cause energy budget effects. They absorb incoming solar radiation, heating up the upper atmosphere but cooling the earth.
What matters:size and composition and amount
primary product
Reported emission rates of levoglucosan from biomass
combustion range from 2-12% of the particle mass.
Particle Composition
Other anhydrous sugars have been seen that correspond to
constituents of hemicellulose and pectin, but not to the same degree.
pyrolysis
Lignin pyrolysis products also abound.Prominent metals:
• Potassium• Sulfur• Chlorine
Terpenoids
Functionally and chemically diverse group of plant compounds.•Hormones•Oils and resins•Pigments•Sterols
Terpenoids are polymers with
commonality of the same basic unit – isoprene.
During wildfires,these terpenoids can be
pyrolyzed and the products emitted
orthey can be directly
emitted by volatilization.
0
10
20
30
40
50
50 250 450 650 850
Particle Diameter (nm)
Pe
rce
nt
of
PM
1.0
Ma
ss
(%
)
total masscellulose pyrolysis productslignin pyrolysis productsresin emissions
0
1
1
2
2
50 250 450 650 850
Particle Diameter (nm)
rati
o o
f c
om
po
nd
pe
rce
nt
to t
ota
l p
erc
en
t
total masscellulose pyrolysis productslignin pyrolysis productsresin emissions
COMPOUND CONCENTRATIONLignin Pyrolysis Products
0
50
100
150
200
250
300
50 250 450 650 850
particle diam eter (nm )
co
mp
ou
nd
co
nc
en
tra
tio
n (
ng
/mg
sa
mp
le)
vanillin guaiacyl acetone
coniferyl aldehyde syringaldehyde
1 10 100 1000 10000 100000 1000000
compound concentration (ng/mg)
resin emissions lignin pyrolysis products cellulose pyrolysis products
Size and Composition
Photo by: Bryan Day, Idaho, 2000
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
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 1984–1994 (APCD 2000)
PM Measurements near Fires
• In Hoopa Valley, CA 1999 PM10 levels exceeded 350 g/m3 for over a week and exceeded the EPA’s hazardous levels of 425 g/m3 for two days (Mott 2001)
• In Hamilton, MT 2000 PM10 levels of 300–600 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).
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)
Experimental Design
•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
•Test the effectiveness of keeping windows closed and air cleaner operation on the indoor air quality
•Monitor indoor and outdoor PM2.5 concentrations at both homes during fire
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
Measurements
• Indoor and outdoor 24-h average PM2.5 mass concentrations using Harvard impactors
• Real-time indoor and outdoor particle # concentrations <0.5 m for 24 h using Climet optical particle counters
• Air-exchange rate using CO2 tracer gas decay method
Air CleanersPRE-FILTER catches larger particlesIONIZING 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
Friedrich C-90a Electrostatic Precipitator
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
Schoonover fire 5/23/02 (NOAA)
The Fires 4/24/02 5:30 PM 1800 acres (NOAA)• The Snaking wildfire
Began 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.
Snaking wildfire 11: 15 am- 3:30 pm (MST) 4/24/02 Snaking wildfire 11: 15 am- 3:30 pm (MST) 4/24/02 (NOAA)(NOAA)
The Biggest Wildfire in Colorado Recorded History!!!
The Hayman wildfire 6/10/02 (NOAA) 11am-5pm.
The FiresThe 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.
Colorado fires on 6/9/02 7:03 pm (NOAA)Colorado fires on 6/9/02 7:03 pm (NOAA)
Data Analysis
AHouse
BHouse
AHouse
cleanerairtodue
reductionPMPercent
OutsidePM
cleanerairowInsidePM
OutsidePM
cleanerairwInsidePM
5.2
5.2
5.2
5.2
5.2
/1
Impact of air cleaners:
Impact of windows closed:
windowsclosedtodue
reductionPMPercent
OutsidePM
InsidePM
OutsidePM
InsidePM
Background
Fire 5.2
5.2
5.2
5.2
5.2
1
Polhemus Prescribed Burn 24-h average PM2.5 (g/m3)
22.0022.00
7.22
3.472.22
1.762.96
37.99
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
House1 fire10/20/01
House 2 fire10/20/01
House 1 bgd11/19/01
House 2 bgd2/19/02
PM 2.5
(ug/m3)
inside
outside2 air cleaners
Cooking event
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
Error bars= data rangeWindows closed
Polhemus Particle Counts
Model assumes: V=815 m3, =0.21 h-1
House 1 OPC, number of particles 0.5-5.0 /m3
0.00E+00
5.00E+07
1.00E+08
1.50E+08
2.00E+08
2.50E+08
10/20/024:48 PM
10/20/027:12 PM
10/20/029:36 PM
10/21/0212:00 AM
10/21/022:24 AM
10/21/024:48 AM
10/21/027:12 AM
10/21/029:36 AM
Mountain time
Co
nce
ntr
atio
n
(#/m
3)
Outside
inside
model
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
Snaking Wildfire 2-day Comparison
63
80
6975
0102030405060708090
100
House 3 to 4 House 4 to 3 House 3 to 3 House 4 to 4
% P
M2.
5 r
educ
tion
AHouse
BHouse
AHouse
cleanerairtodue
reductionPMPercent
OutsidePM
cleanerairowInsidePM
OutsidePM
cleanerairwInsidePM
5.2
5.2
5.2
5.2
5.2
/1
24.3
3.05.5 5.0
33.132.8
5.0 4.6
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
House 10 fire6/18/02
House9 fire6/18/02
House 9 bgd7/16/02
House 10 bgd7/16/02
PM
2.5
ug
/m3 inside
outside
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
Error bars= data range
3 air cleaners installedWindows closed
0.00E+00
5.00E+07
1.00E+08
1.50E+08
2.00E+08
2.50E+08
3.00E+08
6/18/023:36 PM
6/18/026:43 PM
6/18/029:50 PM
6/19/0212:57 AM
6/19/024:04 AM
6/19/027:12 AM
6/19/0210:19 AM
6/19/021:26 PM
6/19/024:33 PM
mountain time
Co
nc
en
tra
tio
n
(#/m
3 )
outside
inside
model
Hayman Wildfire Particle Counts
Model assumes =0.17 h-1, V=510m3
3 air cleaners installed total CADR= 1260 m3h-1
House 9 OPC, number of particles 0.5-5.0 /m3
Indoor PM2.5 Increases during Fires in Homes without Air Cleaners
57
92
59
73
100
0
20
40
60
80
100
House 1 House 3 House 4 House 6 House 10
PM
2.5 (
Indo
or)/
(out
door
)%
Air Cleaners Reduce Indoor PM2.5 during Fires
83 80
62
88 87
0
10
20
30
40
50
60
70
80
90
100
House 2 House 4 House 3 House 5 House 9
% P
M2
.5 r
edu
ctio
n
Results are valid, because homes have similar air exchange rates and indoor/outdoor background measurements
50
19 18
37
21
0
10
20
30
40
50
60
House 1 House 3 House 4 House 6 House 10
%P
M2.
5 r
edu
ctio
n
Keeping Windows Closed during Fires Reduces PM2.5 in Homes
without Air Cleaners
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.
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
Thank You!