Investigation and modeling of the residential infiltration of fine particulate matter in Beijing, China

Figures & data

Table 1. The general household characteristics.

Household characteristics	Nonheating season		Heating season
	n	%	n	%
Building types
Apartment	25	58	25	56
House	5	12	5	11
Quadrangle courtyard	13	30	15	33
Floors
1st–3rd	24	56	27	60
4th–9th	12	28	10	22
>10th	7	16	8	18
Building age
<10 yr	9	21	6	13
10–20 yr	11	26	13	29
>20 yr	23	53	26	58
Total household income (Yuan)
<50,000	3	7	2	4
50,000–100,000	27	63	31	69
100,000–150,000	8	19	7	16
>150,000	5	12	5
Cooking fuel type
No cooking	4	9	5	11
Liquefied gas	11	26	11	24
Coal gas	0	0	3	7
Nature gas	26	61	24	54
Electric	2	5	2	4
Daily cooking frequency
0	4	9	5	11
1	9	26	9	20
2	8	60	9	20
3	22	5	22	49
Use of air conditioner	9	21	0	0
Presence of indoor smoke	9	21	11	24

Table 2. Residential indoor and outdoor levels of PM_2.5 and Finf estimates by season.

	n	Mean	SD	Percentiles
				P0	P25	P50	P75	P100
Nonheating season
Indoor PM2.5 (μg m^−3)	43	59	17	25	45	59	69	104
Outdoor PM2.5 (μg m^−3)	43	73	20	39	58	74	86	107
PM2.5 I/O ratio	43	0.82	0.21	0.47	0.68	0.78	0.94	1.46
Indoor S (μg m^−3)	43	2.98	1.16	1.16	2.04	3.04	3.88	5.27
Outdoor S (μg m^−3)	43	4.43	1.49	1.78	3.91	4.36	5.29	6.66
Finf	43	0.70	0.21	0.23	0.53	0.78	0.86	0.98
Heating season
Indoor PM2.5 (μg m^−3)	45	69	39	19	45	58	83	194
Outdoor PM2.5 (μg m^−3)	45	97	39	30	92	98	119	258
PM2.5 I/O ratio	45	0.77	0.49	0.23	0.52	0.61	0.85	2.7
Indoor S (μg m^−3)	45	2.62	1.67	0.63	1.38	2.09	3.65	7.43
Outdoor S (μg m^−3)	45	4.99	2.73	1	2.47	5.31	6.8	13.57
Finf	45	0.54	0.18	0.27	0.39	0.52	0.67	0.91

Figure 1. Comparison of PM_2.5 Finf between the nonheating season and the heating season for 33 residences monitored in both seasons.

Table 3. Prediction model for Finf in the nonheating season (R² = 0.566).

Independent variables	Coefficient			t	p
	β	SE	β’
(Constant)	–0.058	0.135		–0.431	0.669
Outdoor temperature (ºC)	0.023	0.005	0.678	5.054	<0.001
Daily window opening time during sampling periods (hr)	0.007	0.003	0.313	2.626	0.012
Time of air conditioner use during sampling periods (hr)	–0.006	0.002	–0.432	–2.837	0.007
Window opening width during sampling periods (1 = <10%, 2 = 10–20%, 3 = 20–50%, 4 = 50–80%, 5 = >80%)	0.058	0.024	0.284	2.389	0.022

Table 4. Prediction model for Finf in heating season (R² = 0.175).

Independent variables	Coefficient			t	p
	β	SE	β’
(Constant)	0.541	0.024		22.456	<0.001
Outdoor temperature (ºC)	–0.028	0.009	–0.418	–3.018	0.004