TABLE 2.

Associations between indoor particulate matter concentration and chronic obstructive pulmonary disease health outcomes by weight

Health outcomes	Non-obese participants		Obese participants		Interaction
	β-coefficient/OR (95% CI)	p-value	β-coefficient/OR (95% CI)	p-value	p-value
Indoor PM2.5
Rescue inhaler use#	0.03 (−0.13–0.19)	0.70	0.14 (0.01–0.26)	0.04	0.28
Nocturnal symptoms	OR 0.11 (0.01–1.31)	0.08	OR 1.84 (1.16–2.90)	<0.01	0.03
mMRC dyspnoea scale	−0.01 (−0.21–0.18)	0.89	0.20 (0.05–0.34)	<0.01	0.07
SGRQ total score	0.17 (−2.51–2.85)	0.90	2.40 (0.55–4.27)	0.01	0.17
Frequency of wheeze¶	0.06 (−0.18–0.31)	0.61	0.27 (0.07–0.50)	<0.01	0.18
Exacerbations	OR 0.99 (0.34–2.89)	0.99	OR 1.53 (1.04–2.26)	0.03	0.53
Indoor PM2.5-10
Rescue inhaler use#	−0.13 (−0.56–0.29)	0.54	0.33 (0.13–0.53)	<0.01	0.05
Nocturnal symptoms	OR 0.06 (0.001–6.18)	0.23	OR 5.93 (1.24–28.28)	0.03	0.04
mMRC dyspnoea scale	0.11 (−0.41–0.62)	0.69	0.73 (0.28–1.19)	<0.01	0.07
SGRQ total score	0.59 (−6.03–7.20)	0.86	−0.98 (−6.43–4.47)	0.72	0.98
Frequency of wheeze¶	−0.02 (−0.64–0.59)	0.94	−0.31 (−0.96–0.34)	0.35	0.97
Exacerbations	OR 1.50 (0.02–104.47)	0.85	OR 5.1 (0.93–28.03)	0.06	0.37

For dichotomous outcomes, point estimates represent odds ratios (OR). β-coefficients/OR were calculated based on a 10 μg·m⁻³ change in particulate matter concentration. Models are adjusted for age, sex, education and baseline forced expiratory volume in 1 s. PM_2.5: particulate matter with an aerodynamic size ≤2.5 μm; mMRC: modified Medical Research Council; SGRQ: St George’s Respiratory Questionnaire; PM_2.5-10: particulate matter with an aerodynamic size 2.5–10 μm.

^#rescue inhaler use is represented as daily average use during the week-long monitoring period;

^¶wheeze was assessed using a five-point Likert scale that ascertained frequency in the past 4 weeks.