. 2022 Aug 25;130(8):087008. doi: 10.1289/EHP10734

Table 4.

Association between exposure to residential wood burning and the natural log of fractional exhaled nitric oxide, for all individuals, and by smoking and asthma status, respectively, among $lowercase italic n equals 2598$ participants from the Agricultural Lung Health Study (2009–2013).

Group	Mean ± SD^a	Model estimates^b	Unexposed	Some	Frequent	$p_{interaction}$ ^c
All	2.7 ± 0.63	$n$	2,040	235	323	—
All	—	Beta (95% CI)	Ref	0.03 ( $negative 0.06$ , 0.1)	0.1 (0.02, 0.2)	—
Never smokers	2.70 ± 0.62	$n$	1,373	159	189	—
Never smokers	—	Beta (95% CI)	Ref	$negative 0.01$ ( $negative 0.1$ , 0.1)	0.1 (0.007, 0.2)	—
Former smokers	2.76 ± 0.61	$n$	583	68	110	—
Former smokers	—	Beta (95% CI)	Ref	0.1 ( $negative 0.05$ , 0.2)	$negative 0.02$ ( $negative 0.2$ , 0.1)	0.097
Current smokers	2.19 ± 0.63	$n$	84	8	24	—
Current smokers	—	Beta (95% CI)	Ref	0.09 ( $negative 0.4$ , 0.5)	0.4 (0.1, 0.7)	0.029
Noncase	2.68 ± 0.62	$n$	1,265	136	193	—
Noncase	—	Beta (95% CI)	Ref	0.02 ( $negative 0.08$ , 0.1)	0.1 (0.02, 0.2)	—
Asthma case	2.87 ± 0.73	$n$	775	99	130	—
Asthma case	—	Beta (95% CI)	Ref	0.04 ( $negative 0.09$ , 0.2)	0.01 ( $negative 0.1$ , 0.1)	0.24

Note: —, not applicable; CI, confidence interval, Ref, reference; SD, standard deviation: .

^{^a}

Mean ± SD columns are sample weighted and calculated in units of ln(ppb). These are based on crude values not adjusted for age, gender, height, or any other covariates.

^{^b}

Regression coefficients representing the difference in mean response between participants exposed to wood burning vs. unexposed individuals, holding all covariates constant. Analyses conducted using sample weighted linear regression. Models adjusted for age, gender, height, weight, race/ethnicity, state, smoking status, pack-years, and atopy status. $Wood burning \times smoking status$ and $wood burning \times asthma status$ interaction product terms included to examine potential effect modification by smoking or asthma status, respectively. In parentheses, lower and upper bounds for 95% confidence intervals.

^{^c}

$p$ -Value for difference in the effect of frequent wood burning exposure by smoking and asthma status, respectively, from interaction product terms, after accounting for main effects of wood burning exposure, and smoking or asthma, respectively.