Indoor pollution and burning practices in wood stove management

Figures & data

Table 1. Experimentally determined diffusive uptake rates for 7 days of sampling at a temperature of 298.16 K and a pressure of 1013 mbar

Pollutant	Uptake Rate (mL min^−1)
Benzene	0.34
Toluene	0.44
Ethylbenzene	0.42
m/p-Xylene	0.46
o-Xylene	0.46

Table 2. Descriptive statistics and univariate t tests for paired data

			Benzene	Toluene	Ethylbenzene	Xylenes
			Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)
Sampling	Sampling		Range	Range	Range	Range
Location	Period	N	P value*	P value*	P value*	P value*
Outdoor	August 2007	9	0.88 (0.35)	2.03 (0.98)	0.55 (0.34)	1.84 (0.89)
			0.47–1.58	0.61–3.78	0.05–1.08	0.61–3.60
			<0.001	<0.001	0.743	0.114
	November 2007	7	6.72 (3.36)	4.92 (2.45)	0.67 (0.49)	2.46 (1.52)
			3.93–13.90	2.17–9.41	0.05–1.31	0.80–4.56
			—	—	—	—
	December 2008	8	4.60 (1.47)	1.71 (0.41)	0.41 (0.33)	0.76 (0.70)
			2.46–7.18	1.25–2.60	0.10–0.95	0.20–2.40
			0.239	0.022	0.565	0.021
Room 1	August 2007	9	3.59 (3.29)	30.38 (41.77)	4.28 (5.60)	21.83 (27.31)
			1.35–11.45	4.19–130.53	0.05–17.36	4.32–86.70
			0.001	0.286	0.052	0.080
	November 2007	9	12.22 (4.34)	33.50 (18.38)	9.31 (5.88)	44.11 (36.95)
			5.38–18.20	9.74–64.00	2.41–22.19	11.79–131.03
			—	—	—	—
	December 2008	8	8.34 (2.07)	14.74 (11.98)	3.02 (2.45)	11.64 (10.65)
			5.40–11.90	4.65–39.60	0.90–8.00	2.35–34.25
			0.105	0.003	0.002	0.003
Room 2	August 2007	8	3.74 (3.57)	34.60 (46.52)	5.34 (5.79)	25.62 (30.61)
			1.04–11.58	4.04–131.38	0.38–16.94	2.18–87.20
			0.004	0.299	0.227	0.259
	November 2007	9	11.43 (5.02)	37.27 (21.39)	7.91 (7.08)	37.04 (43.09)
			5.35–21.46	11.57–67.09	1.69–24.89	9.92–148.37
			—	—	—	—
	December 2008	8	11.05 (6.60)	13.96 (10.40)	2.55 (1.11)	11.18 (7.06)
			6.36–26.79	4.20—33.95	1.15–4.25	2.80–20.60
			0.828	<0.001	0.002	0.004

Note: *P value from the t test, using November 2007 as the reference.

Figure 1. Boxplots of the log-transformed pollutant concentrations.

Table 3. Random-effect GLM: Ratio of the average concentration of an pollutant in each season and room with respect to the reference level (November 2007 or room 1)

	Benzene	Toluene	Ethylbenzene	Xylenes
	β	β	β	β
	(95% CI)	(95% CI)	(95% CI)	(95% CI)
Season/Room	P value	P value	P value	P value
August 2007	0.21	0.49	0.47	0.55
	(0.16–0.27)	(0.32–0.74)	(0.27–0.81)	(0.35–0.85)
	<0.001	0.001	0.007	0.008
December 2008	0.82	0.38	0.43	0.30
	(0.64–1.06)	(0.25–0.59)	(0.25–0.75)	(0.19–0.47)
	0.133	<0.001	0.003	<0.001
Outdoor	0.43	0.14	0.12	0.08
	(0.33–0.55)	(0.09–0.21)	(0.07–0.21)	(0.05–0.13)
	<0.001	<0.001	<0.001	<0.001
Room 2	1.03	1.03	1.08	0.96
	(0.80–1.32)	(0.68–1.57)	(0.63–1.87)	(0.62–1.49)
	0.842	0.873	0.780	0.853

Table 4. Random-effect GLM: Variation in the concentration of an pollutant (β) due to an increase of 1 degree of temperature in the house, adjusting by season

Pollutant	β	95% CI	P value
Benzene	1.07	0.97–1.17	0.191
Toluene	1.21	1.06–1.38	0.006
Ethylbenzene	1.15	1.01–1.31	0.049
Xylenes	1.23	1.07–1.42	0.005

Table 5. Outdoor and indoor toluene/benzene (TO/BZ) ratios in wood-heated houses

	August 2007			November 2007			December 2008
		Indoor TO/BZ			Indoor TO/BZ			Indoor TO/BZ
House Code	Outdoor TO/BZ	Room 1	Room 2	Outdoor TO/BZ	Room 1	Room 2	Outdoor TO/BZ	Room 1	Room 2
1	1.1	5.3	7.7	0.7	10.1^b	12.0^b	0.6	5.3	4.5
2	5.0	3.2	2.5	1.5	2.3	2.1	0.3	1.0	1.0
3	3.1	4.6	8.2	0.9	1.5	6.9	0.6	1.8	2.1
4	1.2	11.4^a	11.3^a	0.4	1.3	1.5	0.3	0.5	0.4
5	3.8	9.9^a	12.5^a	0.7	1.1	1.3	na	na	na
6	2.1	2.2	2.6	0.6	1.6	1.7	0.3	1.3	1.1
7	3.6	6.2^a	6.5^a	1.7	3.5	4.1	0.3	0.6	0.4
8	1.2	16.4^a	na	0.8	3.4	2.4	0.4	1.0	0.8
9	1.4	2.4^a	4.3^a	0.5	4.2	3.1	0.4	5.6	1.8
Mean	2.5	6.8	7.0	0.9	3.2	3.9	0.4	2.1	1.6
SD	1.4	4.8	3.7	0.4	2.8	3.5	0.1	2.1	1.3
Median	2.1	5.3	7.1	0.7	2.3	2.4	0.4	1.2	1.0

Notes: na = not available. ^aDeclared use of wood stoves during sampling. ^bDeclared use of solvents during sampling.