Impact of home remediation and household education on indoor air quality, respiratory visits and symptoms in Alaska Native children

Figures & data

Table 1. Indoor air quality measurements pre- and post-remediation in study homes in southwest Alaska, 2011–2016.

Indoor air measurement		Baseline	Post remediation**	1 year after baseline	Random intercept model coeff. for per (p)*
Total VOCs (µg/m^3)	GMC (95% CI)	107 (79, 145)	94 (74, 121)	78 (64, 96)	−0.20 (<0.001)
	Median	99	89	61
BTEX VOCs (µg/m^3)	GMC (95% CI)	53 (37, 77)	49 (36, 66)	32 (24, 44)	−0.32 (<0.001)
	Median	45	44	29
BTEX/Total VOC (%)	Mean (95% CI)	51% (45%, 56%)	52% (47%, 56%)	43% (37%, 49%)	−0.044 (0.001)
	Median	49%	50%	43%
PM2.5 (µg/m^3)	GMC (95% CI)	12.0 (9.4, 15.2)	12.1 (9.2, 15.9)	12.3 (9.7, 15.6)	−0.010 (0.890)
	Median	18	22	15
CO2***(ppm)	GMC (95% CI)	1379 (1194, 1592)	1243 (1117, 1384)	1466 (1248, 1722)	0.027 (0.288)
	Median	1401	1264	1418
RH (%)	Mean (95% CI)	35.9 (33.0, 38.9)	34.5 (31.5, 37.6)	42.7 (39.4, 46.0)	2.51 (0.001)
	Median	35.6	32.6	42.8

* Values are assessed with a linear mixed model (by home) on the log transformed values. Per coded as (1,2,3).

** Post remediation is 1–2 months after baseline.

*** Years 2–4.

The bold values are significant with a p-value <0.05

VOC measurements are one summary over 4 days of collection, PM2.5, CO₂ and RH are mean (RH) and GMC (PM2.5, CO₂) from multiple measurements over the 4 days. Carbon monoxide was measured in years 2–4. 98% of levels (118/121) were <5 ppm, the remaining 3 levels were all <20 ppm.

VOC: volatile organic compounds; GMC: geometric mean concentration; PM2.5: small airway particles; RH: relative humidity; BTEX: total of benzene, toluene, ethylbenzene, o-xylene and m,p-xylene.

Table 2. Coefficients from linear (Ln) models of indoor air quality on time periods after remediation and possible confounding factors in southwest Alaska homes before and after interventions, 2011–2016.

			Coefficient (p-value)
		Time period
		2	3 (Period diff)	Smoking	Woodstove use	Avg num slept in HH	Outdoor air temp	Piped water
Ln(Total VOC)	Univariate	−0.14	−0.41 (<0.001)	−0.036 (0.865)	0.035 (0.798)	0.066 (0.014)	−0.011 (0.002)	−0.930 (<0.001)
	Multivariate	−0.14	−0.37 (0.004)	0.041 (0.833)	0.059 (0.638)	0.055 (0.022)	−0.005 (0.161)	−0.837 (<0.001)
Ln(BTEX)	Univariate	−0.11	−0.65 (<0.001)	−0.069 (0.801)	0.29 (0.101)	0.088 (0.009)	−0.015 (0.001)	−1.205 (<0.001)
	Multivariate	−0.11	−0.61 (<0.001)	−0.006 (0.981)	0.32 (0.037)	0.075 (0.012)	−0.005 (0.245)	−1.08 (<0.001)
Ln(PM2.5)	Univariate	−0.016	−0.019 (0.989)	0.69 (0.003)	0.048 (0.001)	0.058 (0.034)	−0.002 (0.562)	0.016 (0.934)
	Multivariate	−0.051	−0.003 (0.909)	0.72 (0.001)	0.46 (0.002)	0.071 (0.006)	−0.001 (0.774)	0.043 (0.821)
Ln(CO2)	Univariate	−0.078	0.061 (0.012)	−0.008 (0.924)	−0.090 (0.135)	0.058 (<0.001)	0.0004 (0.763)	−0.344 (0.006)
	Multivariate	−0.095	0.109 (<0.001)	0.052 (0.474)	−0.048 (0.349)	0.068 (<0.001)	0.0008 (0.556)	−0.38 (<0.001)
% BTEX	Univariate	0.006	−0.093 (<0.001)	0.023 (0.638)	0.093 (0.002)	0.015 (0.008)	−0.003 (0.002)	−0.140 (<0.001)
	Multivariate	0.006	−0.087 (<0.001)	−0.019 (0.649)	0.095 (0.001)	0.012 (0.021)	−0.001 (0.427)	−0.12 (0.002)
Avg RH	Univariate	−1.14	5.67 (<0.001)	1.11 (0.691)	−3.78 (0.003)	1.031 (0.003)	0.262 (<0.001)	1.11 (0.662)
	Multivariate	−2.41	3.85 (0.001)	1.33 (0.544)	−1.85 (0.197)	1.01 (0.001)	0.25 (<0.001)	−2.79 (0.241)

Household smoking during the air quality sampling period occurred 12% (18/153 sampling periods) of the time, wood stove use occurred 33% (50/153) of the time and 55% (33/60) of the homes had piped water. The average number of people sleeping in the home was 6.7 and the median outdoor air temperature was 16.4°F (min −10.5°F, max 39.4°F).

The bold values are significant with a p-value <0.05

VOC: volatile organic compounds; PM2.5: small airway particles; RH: relative humidity; BTEX: total of benzene, toluene, ethylbenzene, o-xylene and m,p-xylene; Avg Num slept in HH: average number of people sleeping in the home.

Table 3. Parent-reported respiratory symptoms on an interval questionnaire adjusted for age category and season; high-risk status as factor, in Alaska study homes, before and after household interventions, 2011–2016. No interactions between high-risk and post- intervention are significant.

	Pre		Post
						Post
	Initial visit (n = 204)	Pre-intervention (n = 203)	2-weeks post (n = 198)	3-months post (n = 174)	1-year post (n = 155)	Odds Ratio (p-value)
Cold or runny nose?	118 (58%)	111 (55%)	83 (42%)	80 (46%)	64 (41%)	0.53 (0.003)
Any cough between colds?	74 (36%)	86 (43%)	60 (30%)	58/173 (34%)	39/154 (25%)	0.57 (0.004)
Any wet cough?	51/202 (25%)	42/202 (21%)	33/197 (17%	45/173 (20%)	19/152 (13%)	0.61 (0.037)
Any wheezing or whistling?	36/202 (18%)	31/202 (15%)	26 (12%)	29/172 (17%)	12/152 (8%)	0.60 (0.057)
Any wheezing between colds?	22 (11%)	10 (5%)	3 (2%)	5 (3%)	6 (4%)	0.40 (0.020)
Any wheezing attack?	7 (3%)	11 (5%)	3 (2%)	5 (3%)	6 (4%)	0.73 (0.497)
Needed inhaler or nebuliser?	42/203 (21%)	35/202 (17%)	23/197 (12%)	32/172 (19%)	15/153 (10%)	0.58 (0.049)
Any missed school for illness?	23/138 (17%)	19/127 (15%)	13/132 (10%)	6/67 (9%)	3/112 (3%)	0.19 (<0.001)

The bold values are significant with a p-value <0.05

Table 4. Matched comparison of healthcare visits in all household children and adults, in Alaska study homes before and after household interventions, 2011–2016.

		Children			Adults*
		Pre**	Post	p-value***	Pre	Post	p-value
N		182			79
All Visits	Mean (±SE)****	13.6 (±0.77)	11.2 (±0.64)	<0.001	10.5 (±1.24)	11.3 (±1.57)	0.578
	Median	11.5	9	<0.001	7	8	0.833
ARI	Mean (±SE)	6.99 (±0.57)	5.24 (±0.43)	<0.001	2.41 (±0.37)	2.25 (±0.36)	0.574
	Median	4	3.5	<0.001	1	1	0.532
LRTI	Mean (±SE)	1.91 (±0.25)	1.36 (±0.19)	0.007	0.72 (±0.19)	0.49 (±0.15)	0.095
	Median	0	0	0.013	0	0	0.119
Antibiotic	Mean (±SE)	4.05 (±0.31)	4.01 (±0.31)	0.902	2.71 (±0.46)	3.06 (±0.41)	0.448
	Median	3	3	0.611	1	2	0.093
Albuterol	Mean (±SE)	1.84 (±0.21)	2.64 (±0.30)	0.007	1.90 (±0.46)	1.75 (±0.41)	0.763
	Median	1	1	0.075	0	0	0.827
Asthma Rx	Mean (±SE)	2.02 (±0.23)	2.88 (±0.31)	0.003	2.13 (±0.48)	1.91 (±0.42)	0.672
	Median	1	1	0.032	0	0	0.578

* Adult data are available for 3 villages from years 3 and 4.

** Pre and Post periods are 1 year in length except for year 1 villages where the period is 8 months.

*** p-values are calculated with a matched t-test (mean) and signrank test (median).

**** SE: Standard error of the mean.

The bold values are significant with a p-value <0.05

ARI: acute respiratory infections; LRTI: lower respiratory tract infections; Rx: prescription.

Table 5. Poisson regression of number of visits pre- and post-household interventions, using random effects model with random effect for person, for children in study households, 2011–2016.

	High-risk children		Other household children		All children
	Coefficient (95% CI)		Coefficient (95% CI)		Coefficient (95% CI)
		Adj*		Adj*		Adj*
All Visits
All	−0.32 (−0.40, −0.23)	−0.12 (−0.24, −0.005)	−0.20 (−0.18, −0.02)	0.03 (−0.06, 0.12)	−0.20 (−0.26, −0.14)	−0.012 (−0.08, 0.06)
ARI	−0.41 (−0.53, −0.29)	−0.13 (−0.29, 0.03)	−0.16 (−0.28, −0.04)	0.09 (−0.06, 0.23)	−0.29 (−0.37, −0.21)	0.02 (−0.09, 0.13)
LRTI	−0.56 (−0.78, −0.34)	−0.32 (−0.61, −0.03)	−0.02 (−0.28, 0.22)	0.67 (0.32, 1.03)	−0.34 (−0.50, −0.17)	0.16 (−0.06, 0.39)
Antibiotic Rx	−0.18 (−0.35, −0.02)	0.02 (−0.19, 0.23)	0.09 (−0.04, 0.23)	0.29 (0.14, 0.44)	−0.01 (−0.11, 0.09)	0.22 (0.10, 0.33)
Albuterol Rx	0.19 (−0.03, 0.41)	0.36 (0.09, 0.63)	0.47 (0.29, 0.66)	0.59 (0.38, 0.81)	0.36 (0.22, 0.50)	0.52 (0.35, 0.68)
Asthma Rx	0.21 (0.01, 0.41)	0.34 (0.09, 0.59)	0.46 (0.28, 0.64)	0.59 (0.38, 0.79)	0.35 (0.22, 0.49)	0.51 (0.35, 0.66)

*Adjusted model includes adjustment for age as three linear splines (<2, 2–3, 4–13 years).

Includes participants available for entire pre and post periods.

The bold values are significant with a p-value <0.05

LRTI: lower respiratory tract infection; ARI: acute respiratory infection; Rx: prescription.