Impacts of prescribed fires and benefits from their reduction for air quality, health, and visibility in the Pacific Northwest of the United States

Figures & data

Table 1. Metrics used for performance evaluation (Boylan and Russell 2006; Chen et al. 2008).

Metric	Equation
Mean fractional bias (%)	$FB=\frac{1}{N}\sum _{i=1}^N\frac{\left(C_m-C_o\right)}{\left(C_m+C_o\right)/2}\ast 100$
Mean fractional error (%)	$FE=\frac{1}{N}\sum _{i=1}^N\frac{\left|C_m-C_o\right|}{\left(C_m+C_o\right)/2}\ast 100$
Normalized mean bias (%)	$NB=\frac{{\sum }_{i=1}^N\left(C_m-C_o\right)}{{\sum }_{i=1}^N{C}_o}\ast 100$
Normalized mean error (%)	$NE=\frac{{\sum }_{i=1}^N\left|C_m-C_o\right|}{{\sum }_{i=1}^N{C}_o}\ast 100$
Mean bias	$MB=\frac{1}{N}\sum _{i=1}^N\left(C_m-C_o\right)$
Mean error	$ME=\frac{1}{N}\sum _{i=1}^N\left|C_m-C_o\right|$
Root mean square error (RMSE)	$RMSE={\left(\frac{1}{N}\sum _{i=1}^N\left(C_m-C_o\right)\right)}^{1/2}$
Correlation coefficient (r)	$r=\frac{{\sum }_{i=1}^N\left(C_m-\overline{C_m}\right)\left(C_o-\overline{C_o}\right)}{{\left[{\sum }_{i=1}^N{\left(C_m-\overline{C_m}\right)}^2{\sum }_{i=1}^N{\left(C_o-\overline{C_o}\right)}^2\right]}^{1/2}}$
Mean fractional bias goal (%)	$\left|MFB\right|\le 170e^{\left[\frac{-0.5\left(\overline{C_o}+\overline{C_m}\right)}{0.5}\right]}+30$
Mean fractional bias criteria (%)	$\left|MFB\right|\le 140e^{\left[\frac{-0.5\left(\overline{C_o}+\overline{C_m}\right)}{0.5}\right]}+60$
Mean fractional error goal (%)	$MFE\le 150e^{\left[\frac{-0.5\left(\overline{C_o}+\overline{C_m}\right)}{0.75}\right]}+50$
Mean fractional error criteria (%)	$MFE\le 125e^{\left[\frac{-0.5\left(\overline{C_o}+\overline{C_m}\right)}{0.75}\right]}+75$

Figure 1. Emissions of PM_2.5 from wildfires and prescribed burns for 2011 based on NEI-2011. For each month, the stacked bar on the left is for wildfire and the bar on the right is for prescribed fire.

Table 2. Performance metrics for PM2.5 at the AQS and IMPROVE sites.

	AQS sites			IMPROVE sites
Metric	No fire	Fire		No fire		Fire
Number of observed–modeled pairs	6561			537
Mean observed (µg/m^3)	8.41			2.83
Mean modeled (µg/m^3)	7.54		9.82	2.06		3.88
MB (µg/m^3)	−0.87		1.41	−0.74		1.11
ME (µg/m^3)	5.17		5.94	1.55		2.12
MFB (%)	−19		1	−21		19
MFE (%)	61		59	57		54
NMB (%)	−10		17	−26		39
NME (%)	62		71	55		75
RMSE	7.71		9.42	2.81		4.16

Figure 2. Modeled to observed ratio versus observed PM_2.5 concentrations for AQS and IMPROVE sites.

Figure 3. Bugle plots for comparison of MFB and MFE with goals and criteria for PM_2.5 during the period of simulation.

Table 3. Performance metrics at the IMPROVE sites.

			With fire						No fire
Species	Number observed	Mean observed (µg/m^3)	Bias (µg/m^3)	MFB (%)	MFE (%)	NMB (%)	NME (%)	RMSE (µg/m^3)	Bias (µg/m^3)	MFB (%)	MFE (%)	NMB (%)	NME (%)	RMSE (µg/m^3)
OC	490	1.21	0.06	−17	73	5	75	4.68	−0.74	−105	114	−26	55	4.46
EC	488	0.17	0.18	46	75	110	160	0.76	−0.98	−33	73	−43	55	0.49
SO4^2-	502	0.33	0.20	55	66	61	78	0.33	−0.07	42	59	36	62	0.26
NH4^+	502	0.16	0.02	−4	64	10	71	0.19	0.12	−35	69	−29	58	0.13
NO3^−	502	0.14	0.19	48	100	141	183	0.49	−0.05	22	94	64	122	0.31

Figure 4. Modeled and observed deciview comparison for all days and 20% worst visibility days within the simulation period.

Figure 5. (a) PM_2.5 difference between the 100% fire case and the no fire case when averaged over all days in the simulation period. (b) Percent change in PM_2.5 concentrations when all the fire emissions are uniformly reduced by 70%. Results for only those model grid cells where PM_2.5 concentrations for 100% fire case is greater than 12 μg/m³ are shown.

Figure 6. PM_2.5 distributions at selected sites for the three different scenarios. Whiskers represent 2nd and 98th percentiles.

Table 4. Impact estimates for various health endpoints for no fire and 30% fire case (control cases) with 100% fire case (base case).

Health endpoint	Author	Impact estimate Δy = y100% Fire – yNo Fire	Impact estimate Δy = y100% Fire – y30% Fire
Mortality (all cause)	Krewski et al. (2009)	277	196
	Laden et al. (2006)	707	501
	Pope et al. (2002)	277	196
	Zanobetti and Schwartz (2009)	49	34
Acute bronchitis	Dockery et al. (1996)	398	283
Acute myocardial infarction (nonfatal)	Sullivan et al. (2005)	19	14
	Zanobetti et al. (2009)	22	16
Asthma exacerbation (cough)	Mar et al. (2004)	79,878	59,311
Asthma exacerbation (shortness of breath)	Mar et al. (2004)	26,972	20,371
Chronic bronchitis	Abbey et al. (1995)	190	135
Emergency-room visits (asthma)	Mar, Koenig, and Primomo (2010)	125	90
	Slaughter et al. (2005)	67	48
Hospital admissions all cardiovascular (less myocardial infarctions)	Bell et al. (2008)	24	17
	Peng et al. (2009)	21	15
	Delfino et al. (2009)	47	33
Hospital admissions all respiratory	Zanobetti et al. (2009)	49	35
	Delfino et al. (2009)	124	87
Lower respiratory symptoms	Schwartz and Neas (2000)	4,386	3,294
Upper respiratory symptoms	Pope et al. (1991)	7,286	5,186
Minor restricted activity days	Ostro and Rothschild (1989)	207,588	150,042
Work loss days	Ostro (1987)	35,662	25,568

Figure 7. Prescribed fire attributed additional asthma attacks and mortality cases for various states in AIRPACT-4 model domain.

Figure 8. Deciview distribution for the grid cells in class I areas for the three emission scenarios.

Table 5. Changes in average deciviews for the haziest 20% days during October–November 2011 at IMPROVE sites. Sites where the deciview improvements for the recued fire case are comparable with the Theil trend are shown in bold.

Site name	Site code	Deciview for 100% fire case	delta dv 100 % fire – No fire	delta dv 100% fire – 30% fire	Theil trend (dv/year)
Columbia River Gorge	CORI1	20.87	−0.13	−0.05	−0.10
Columbia Gorge #1	COGO1	19.42	−0.01	−0.02	−0.50
Three Sisters wilderness	THSI1	18.74	−0.09	−0.04	−0.10
Glacier NP	GLAC1	18.17	−0.17	−0.07	−0.18
Redwood NP	REDW1	17.93	−0.08	−0.03	−0.17
Mount Rainier NP	MORA1	16.97	0.00	0.00	−0.34
Starkey	STAR1	16.85	−0.16	−0.05	−0.44
Kalmiopsis	KALM1	16.85	−0.13	−0.06	−0.14
Hells Canyon	HECA1	16.49	−0.11	−0.05	−0.16
Mount Hood	MOHO1	16.26	−0.09	−0.04	−0.16
Trinity	TRIN1	16.15	−0.04	−0.02	−0.16
Snoqualmie Pass	SNPA1	15.96	−0.07	−0.03	−0.28
Monture	MONT1	15.94	−0.19	−0.09	−0.10
Flathead	FLAT1	15.77	−0.13	−0.06	−0.32
Olympic	OLYM1	15.77	−0.02	−0.01	−0.28
Craters of the Moon NM	CRMO1	15.01	−0.04	−0.02	−0.04
Lassen Volcanic NP	LAVO1	14.92	−0.07	−0.03	0.02
Cabinet Mountains	CABI1	14.65	−0.13	−0.06	−0.08
Sula Peak	SULA1	14.49	−0.01	0.00	0.00
Lava Beds NM	LABE1	13.59	−0.13	−0.06	−0.05
Crater Lake NP	CRLA1	13.48	−0.16	−0.07	−0.06
North Cascades	NOCA1	13.38	−0.01	0.00	0.00
Pasayten	PASA1	13.21	−0.06	−0.03	−0.29
Sawtooth NF	SAWT1	12.75	−0.01	0.00	−0.13
Gates of the Mountains	GAMO1	11.51	−0.03	−0.01	−0.01
White Pass	WHPA1	11.38	−0.10	−0.04	−0.11

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