Table 3.

Factor change and 95% confidence interval (95%CI) in log-transformed PM_2.5 exposure (μg/m³) by time, location, surrounding building density and nearby roadways among children and mothers in the Child Lung Function Study¹. Estimated with linear mixed effects models with nested random effects: community and participant ID. Results for model series a) one-minute data, b) 30-minute averaged data and c) 30-minute averaged data with first-order autocorrelation structure within participant.

		a) One-minute	b) 30-minute	c) 30-minute autoregressive
		Factor (95CI)2	Factor % (95CI)	Factor % (95CI)
MODEL 1: Time of day and location
Time of day
Nighttime (21–4 next day)		REF	REF	REF
Morning cook hours (5–9)		1.62 (1.6, 1.64)	1.72 (1.64, 1.81)	1.44 (1.36, 1.54)
Evening cook hours (16–20)		2.50 (2.47, 2.52)	2.74 (2.62, 2.87)	1.63 (1.54, 1.74)
Other daytime hours		1.12 (1.11, 1.13)	1.16 (1.12, 1.21)	1.18 (1.13, 1.23)
Participant location
Outside both boundaries (elsewhere)		REF	REF	REF
Household vicinity		2.15 (2.12, 2.18)	2.12 (1.98, 2.28)	2.17 (1.99, 2.37)
Community boundaries		1.65 (1.62, 1.68)	1.60 (1.46, 1.76)	1.70 (1.54, 1.89)
Harmattan season
No		REF	REF	REF
Yes		3.17 (2.47, 4.08)	3.20 (2.53, 4.05)	3.07 (2.44, 3.85)
Participant type
Child		REF	REF	REF
Mother		0.68 (0.55, 0.84)	0.74 (0.61, 0.91)	0.77 (0.64, 0.94)
Wearing compliance
No		REF	REF	REF
Yes		1.37 (1.36, 1.39)	1.36 (1.31, 1.41)	1.23 (1.19, 1.27)
Conditional R2		0.413	0.498	0.384
MODEL 2: Location-time environment 3
Household, nighttime		REF	REF	REF
Household, morning cook hrs		1.58 (1.56, 1.6)	1.69 (1.61, 1.78)	1.44 (1.35, 1.53)
Household, evening cook hrs		2.61 (2.58, 2.63)	2.84 (2.70, 2.98)	1.71 (1.61, 1.82)
Household, other daytime hours		1.10 (1.09, 1.11)	1.14 (1.10, 1.19)	1.18 (1.13, 1.23)
Community, morning cook hrs		1.41 (1.37, 1.44)	1.49 (1.28, 1.72)	1.14 (1.00, 1.3)
Community, evening cook hrs		1.81 (1.76, 1.85)	1.80 (1.54, 2.10)	1.37 (1.20, 1.56)
Community, other daytime hours		0.85 (0.84, 0.87)	0.89 (0.82, 0.97)	0.91 (0.83, 1.00)
Another place/time		0.61 (0.60, 0.62)	0.62 (0.58, 0.67)	0.63 (0.57, 0.69)
Conditional R 2		0.414	0.499	0.385
MODEL 3: Surrounding building density 3,4
Quartiles building density (500m)
Q1[0.000,0.011)		REF	REF	REF
Q2[0.011,0.018)		0.89 (0.86, 0.91)	0.90 (0.80, 1.02)	0.96 (0.84, 1.08)
Q3[0.018,0.032)		1.42 (1.39, 1.46)	1.47 (1.31, 1.65)	1.28 (1.13, 1.45)
Q4[0.032,0.155]		1.57 (1.53, 1.61)	1.60 (1.42, 1.80)	1.36 (1.19, 1.55)
Conditional R2		0.426	0.518	0.396
MODEL 4: Proximal to roadways 3,4,5
On or nearby (100m) road type?
Trunk	No	REF	REF	REF
	Yes	1.13 (1.11, 1.14)	1.16 (1.07, 1.25)	1.23 (1.15, 1.32)
Secondary	No	REF	REF	REF
	Yes	0.93 (0.91, 0.95)	0.90 (0.81, 1.00)	1.00 (0.91, 1.11)
Tertiary	No	REF	REF	REF
	Yes	1.6 (1.55, 1.66)	1.68 (1.45, 1.95)	1.31 (1.13, 1.51)
Unclassified	No	REF	REF	REF
	Yes	0.97 (0.95, 0.99)	0.97 (0.89, 1.06)	1.02 (0.94, 1.10)
Residential	No	REF	REF	REF
	Yes	0.83 (0.81, 0.84)	0.77 (0.70, 0.85)	0.93 (0.84, 1.02)
Service	No	REF	REF	REF
	Yes	0.69 (0.65, 0.73)	1.15 (0.87, 1.52)	1.12 (0.91, 1.38)
Track	No	REF	REF	REF
	Yes	1.10 (1.05, 1.15)	1.27 (1.06, 1.53)	1.18 (1.01, 1.39)
Footway	No	REF	REF	REF
	Yes	1.28 (0.9, 1.82)	0.54 (0.27, 1.08)	0.96 (0.65, 1.41)
Conditional R2	0.435	0.531	0.400
Model 4.1: Roadway density (100m) 3,4,5
Trunk	Zero	REF	REF	REF
	<median (1, 164m)	1.07 (1.05, 1.09)	1.12 (1.03, 1.22)	1.21 (1.13, 1.31)
	≥median (165, 403m)	1.18 (1.16, 1.21)	1.19 (1.08, 1.31)	1.28 (1.17, 1.41)
Tertiary	Zero	REF	REF	REF
	<median (3, 168m)	1.44 (1.38, 1.50)	1.34 (1.13, 1.59)	1.21 (1.05, 1.40)
	≥median (169, 263m)	1.64 (1.58, 1.71)	1.83 (1.54, 2.19)	1.62 (1.33, 1.98)
Track	Zero	REF	REF	REF
	<median (0.3, 104m)	1.05 (1.00, 1.11)	1.08 (0.87, 1.34)	1.18 (0.99, 1.39)
	≥median (105, 344m)	1.25 (1.17, 1.33)	1.77 (1.37, 2.28)	1.31 (1.02, 1.69)
Conditional R2		0.430	0.523	0.404

¹Includes 259 participant sessions with geo-located PM_2.5 measurements

²Computed as the exponent of the beta coefficient [$e^{\beta }$]

³Adjusted for Harmattan season, participant type, and wearing compliance

⁴Additionally adjusted for location-time environment

⁵Additionally adjusted for building density