Polluting fuels, including biomass (e.g. wood, charcoal), coal and kerosene, are used by approximately 3.8 billion individuals worldwide for cooking, heating and lighting.1 Household air pollution (HAP) generated from incomplete combustion of these fuels results in fine particulate matter (PM2.5) levels typically well above World Health Organization (WHO) guidelines.2 Exposure to PM2.5 in HAP is causally associated with many adverse health outcomes, including cardiopulmonary, and respiratory diseases.3–6 Polluting fuel use also negatively impacts climate through deforestation from unsustainable harvesting of wood in certain locations,7 and emissions of short-term climate-forcing pollutants; 25% of global anthropogenic black carbon emissions are produced through household biomass combustion.7,8 Women, typically the primary cook, may travel long distances to gather polluting fuels in some settings, which negatively impacts their livelihoods.9,10
In Sub-Saharan Africa (SSA), approximately 900 million people cook with polluting fuels.11 Governments in SSA, including Cameroon, Ghana and Kenya, plan to expand population-level use of liquefied petroleum gas (LPG) as an interim solution for clean cooking to an aspirational target of between 35% and 58% over the next decade.12–14 LPG, although a fossil fuel, does not emit black carbon, and has much lower PM2.5 emissions than polluting fuels.12,15,16 Using LPG for cooking can also decrease localized deforestation, and reduce time spent gathering and cooking with polluting fuels.16,17
Historically, studies focused on determinants of clean cooking have emphasized the ‘household energy ladder’ model, by which improvements in socioeconomic status (SES) lead households to progressively transition to cleaner energy sources.18–20 However, other aspects, including consistent fuel access, safety and convenience are also important facilitators of clean cooking fuel uptake.21–23 Studies in India found that rural households provided with subsidies for LPG connections under the Pradhan Mantri Ujjwala Yojana (PMUY) programme continued to use polluting fuels alongside LPG (‘stove stacking’), leading to less frequent LPG use compared with urban households.24,25 Reduced LPG uptake likely resulted from poorer supply and access points in rural Indian villages. While studies conducted in Cameroon,26,27 Tanzania28 and Ethiopia29 have also found supply-related issues to be important determinants of cooking fuel decisions, few large-scale studies in SSA have quantitatively assessed their effect on LPG consumption.
As partial use of clean cooking fuels (stacked with polluting fuels) does not provide sufficient HAP exposure reductions to benefit health,30 a comprehensive understanding of facilitators for sustained and exclusive LPG use is critical to maximizing health gains. This multinational modeling study of over 5,500 households in peri-urban communities of Mbalmayo, Cameroon; Eldoret, Kenya and Obuasi, Ghana, presents one of the largest assessments of supply-related impacts on LPG fuel usage in SSA. With urban populations in SSA predicted to double over the next 25 years, this analysis provides a timely examination across three rapidly developing communities.
Cooking Environment Characteristics
The final sample included 5,638 households (Obuasi, Ghana:1,987 (35%); Mbalmayo, Cameroon:1,811 (32%); Eldoret, Kenya:1,840 (33%)). Participants that did not cook at home (n=416; 7%) were excluded. The proportion of individuals primarily cooking with LPG varied substantially by community (Obuasi:38% (n=757), Mbalmayo:28% (n=468), Eldoret:5% (n=35)) (Figure 1).
Figure 1. Primary cooking fuel types among three peri-urban communities in Ghana, Cameroon and Kenya
Sixty percent (n=2,772) of households ‘stacked’ at least two cooking fuels. Fuel stacking was 30% higher among households primarily using LPG (82%) compared with households primarily using polluting fuels (53%). Fuel stacking prevalence among households primarily cooking with polluting fuels was approximately 20% higher in Eldoret and Mbalmayo (60%) compared with Obuasi (40%).
A higher percentage of households primarily cooking with LPG contained a member with a university degree (22%) and were in the highest income quartile (23%), compared with households primarily using polluting cooking fuels (5% with university degree; 8% in highest income quartile) (Table 1). In Eldoret and Mbalmayo, the proportion of households cooking primarily with polluting fuels that reported seasonal changes in income (72% and 75%, respectively) was 20-30% higher than those primarily cooking with LPG (42% and 58%, respectively). Among households primarily cooking with LPG, 59% had fewer than 5 family members, compared with 38% of those primarily cooking with polluting fuels (Table 1).
Table 1. Socioeconomic and cooking environment characteristics of study households (n=4,555)
|
Overall
(N=4555)
|
Mbalmayo, Cameroon
(N=1811)
|
Obuasi, Ghana
(N=1987)
|
Eldoret, Kenya*
(N=757)
|
Characteristic
|
LPG Primary
(N=1260)
|
Polluting
Primary
(N=3295)
|
LPG Primary
(N=468)
|
Polluting
Primary
(N=1343)
|
LPG Primary
(N=757)
|
Polluting
Primary
(N=1230)
|
LPG Primary
(N=35)
|
Polluting
Primary
(N=722)
|
Cooking fuel stacking (%)
|
1029
(82%)
|
1743
(53%)
|
389
(83%)
|
788
(59%)
|
610
(81%)
|
478
(39%)
|
30
(86%)
|
477
(66%)
|
# of cooking fuels used
|
|
|
|
|
|
|
|
|
One
|
231 (18%)
|
1552 (47%)
|
79 (17%)
|
555 (41%)
|
147 (19%)
|
752 (61%)
|
5 (14%)
|
245 (34%)
|
Two
|
875 (69%)
|
1296 (39%)
|
264 (56%)
|
565 (41%)
|
587 (78%)
|
398 (32%)
|
24 (68%)
|
333 (46%)
|
Three
|
106 (8%)
|
322 (10%)
|
81 (17%)
|
130 (10%)
|
20 (3%)
|
74 (6%)
|
5 (14%)
|
118 (16%)
|
Four or more
|
51 (4%)
|
125 (4%)
|
44 (9%)
|
93 (8%)
|
3 (0%)
|
6 (1%)
|
1 (3%)
|
26 (4%)
|
Age (Mean SD)
|
35 (12)
|
39 (15)
|
33 (12)
|
36 (15)
|
36 (11)
|
40 (14)
|
33 (12)
|
41 (15)
|
Sex of fuel decision maker (% Female)
|
632
(78%)
|
1748
(87%)
|
34
(79%)
|
116
(85%)
|
572
(78%)
|
1006
(84%)
|
26
(76%)
|
626
(92%)
|
Marital status
|
|
|
|
|
|
|
|
|
Married
|
609 (49%)
|
1634 (49%)
|
147 (31%)
|
477 (36%)
|
437 (58%)
|
632 (51%)
|
25 (71%)
|
525 (73%)
|
Single
|
394 (31%)
|
873 (26%)
|
167 (36%)
|
455 (34%)
|
219 (29%)
|
302 (25%)
|
8 (23%)
|
116 (16%)
|
Cohabitating
|
184 (15%)
|
414 (13%)
|
129 (28%)
|
288 (21%)
|
54 (7%)
|
123 (10%)
|
1 (3%)
|
3 (0%)
|
Widowed
|
31 (2%)
|
286 (9%)
|
20 (4%)
|
102 (8%)
|
10 (1%)
|
114 (9%)
|
1 (3%)
|
70 (10%)
|
Divorced
|
42 (3%)
|
88 (3%)
|
5 (1%)
|
21 (2%)
|
37 (5%)
|
59 (5%)
|
0
|
8 (1%)
|
Home size (# of members)
|
|
|
|
|
|
|
|
|
1-2
|
272 (22%)
|
380 (12%)
|
47 (10%)
|
84 (6%)
|
212 (28%)
|
245 (20%)
|
13 (37%)
|
51 (7%)
|
3-4
|
463 (37%)
|
865 (26%)
|
150 (32%)
|
274 (20%)
|
297 (39%)
|
395 (32%)
|
16 (46%)
|
196 (27%)
|
5-6
|
338 (27%)
|
1002 (30%)
|
138 (29%)
|
372 (28%)
|
196 (26%)
|
374 (30%)
|
4 (11%)
|
256 (35%)
|
7+
|
187 (15%)
|
1047 (32%)
|
133 (28%)
|
612 (46%)
|
52 (7%)
|
216 (18%)
|
2 (6%)
|
219 (30%)
|
Cooking location
|
|
|
|
|
|
|
|
|
Indoors (separate structure)
|
98 (8%)
|
1404 (43%)
|
71 (15%)
|
675 (50%)
|
23 (3%)
|
105 (9%)
|
4 (11%)
|
624 (86%)
|
Outside (open air)
|
23 (2%)
|
512 (16%)
|
8 (2%)
|
367 (27%)
|
15 (2%)
|
134 (11%)
|
0
|
11 (2%)
|
Veranda/porch
|
428 (34%)
|
715 (22%)
|
0
|
117 (9%)
|
428 (57%)
|
633 (51%)
|
0
|
0
|
Inside (separate room)
|
479 (38%)
|
435 (13%)
|
253 (54%)
|
69 (5%)
|
216 (29%)
|
328 (27%)
|
10 (29%)
|
38 (5%)
|
Inside (single room)
|
212 (17%)
|
142 (4%)
|
118 (25%)
|
75 (6%)
|
73 (10%)
|
27 (2%)
|
21 (60%)
|
40 (6%)
|
Heating fuel
|
|
|
|
|
|
|
|
|
None
|
757 (60%)
|
1229 (37%)
|
465 (100%)
|
1338 (100%)
|
757 (100%)
|
1230 (100%)
|
15 (43%)
|
198 (27%)
|
Manufactured stove
|
15 (2%)
|
424 (13%)
|
0
|
0
|
0
|
0
|
15 (43%)
|
424 (59%)
|
Open fire
|
3 (0%)
|
36 (1%)
|
2 (0%)
|
4 (0%)
|
0
|
1 (0%)
|
1 (3%)
|
31 (4%)
|
Nonmanufactured stove
|
4 (0%)
|
70 (2%)
|
0
|
1 (0%)
|
0
|
0
|
4 (11%)
|
69 (10%)
|
Lighting fuel
|
|
|
|
|
|
|
|
|
Electricity (grid or solar)
|
1251 (99%)
|
2819 (85%)
|
466 (100%)
|
1250 (93%)
|
755 (100%)
|
1181 (96%)
|
30 (86%)
|
388 (54%)
|
Solar-powered lantern
|
4 (0%)
|
230 (7%)
|
1 (0%)
|
35 (3%)
|
0
|
0
|
3 (8%)
|
195 (27%)
|
Kerosene lamp
|
3 (0%)
|
124 (4%)
|
1 (0%)
|
36 (3%)
|
0
|
0
|
2 (6%)
|
88 (12%)
|
Rechargeable flashlight
|
0
|
38 (1%)
|
0
|
4 (0%)
|
0
|
13 (1%)
|
0
|
0
|
Battery-powered flashlight
|
1 (0%)
|
50 (2%)
|
0
|
1 (0%)
|
1 (0%)
|
35 (3%)
|
0
|
14 (2%)
|
Candle
|
0
|
9 (0%)
|
0
|
4 (0%)
|
0
|
0
|
0
|
5 (1%)
|
Oil or LPG lamp
|
1 (0%)
|
9 (0%)
|
0
|
1 (0%)
|
1 (0%)
|
1 (0%)
|
0
|
7 (1%)
|
Country-standardized HH income quartile
|
|
|
|
|
|
|
|
|
1 (lowest)
|
77 (6%)
|
662 (20%)
|
13 (3%)
|
122 (9%)
|
48 (6%)
|
133 (11%)
|
16 (46%)
|
407 (56%)
|
2
|
212 (17%)
|
558 (17%)
|
106 (22%)
|
219 (16%)
|
102 (13%)
|
280 (23%)
|
4 (11%)
|
59 (8%)
|
3
|
329 (26%)
|
497 (15%)
|
70 (15%)
|
111 (8%)
|
258 (34%)
|
378 (31%)
|
1 (3%)
|
8 (1%)
|
4 (highest)
|
293 (23%)
|
264 (8%)
|
12 (3%)
|
6 (0%)
|
281 (37%)
|
256 (21%)
|
0
|
2 (0%)
|
Not disclosed/do not know
|
165 (13%)
|
710 (22%)
|
151 (32%)
|
464 (35%)
|
0
|
0
|
14 (40%)
|
246 (34%)
|
Seasonal changes in income
|
|
|
|
|
|
|
|
|
Yes
|
799 (65%)
|
1980 (71%)
|
270 (58%)
|
335 (75%)
|
524 (69%)
|
821 (67%)
|
5 (42%)
|
151 (72%)
|
Obtain cooking fuels for free
|
|
|
|
|
|
|
|
|
Yes
|
53 (4%)
|
1136 (34%)
|
33 (7%)
|
423 (31%)
|
14 (2%)
|
245 (20%)
|
6 (17%)
|
468 (65%)
|
Highest HH education level
|
|
|
|
|
|
|
|
|
No formal education
|
43 (3%)
|
246 (5%)
|
3 (1%)
|
115 (9%)
|
40 (5%)
|
163 (13%)
|
0
|
57 (8%)
|
Primary
|
108 (9%)
|
791 (17%)
|
66 (14%)
|
722 (54%)
|
37 (5%)
|
139 (11%)
|
8 (23%)
|
194 (27%)
|
Secondary/high school
|
815 (65%)
|
1706 (37%)
|
302 (65%)
|
469 (35%)
|
508 (67%)
|
852 (69%)
|
5 (14%)
|
132 (18%)
|
University
|
272 (22%)
|
227 (5%)
|
96 (21%)
|
26 (2%)
|
170 (22%)
|
75 (6%)
|
6 (17%)
|
37 (5%)
|
Main water source
|
|
|
|
|
|
|
|
|
Well (pit with bucket)
|
277 (22%)
|
1333 (40%)
|
122 (26%)
|
534 (40%)
|
134 (18%)
|
265 (22%)
|
21 (60%)
|
534 (74%)
|
Communal standpipe
|
444 (35%)
|
921 (28%)
|
117 (25%)
|
307 (23%)
|
325 (43%)
|
598 (49%)
|
2 (6%)
|
16 (2%)
|
Pipe in home
|
472 (37%)
|
730 (22%)
|
192 (41%)
|
344 (26%)
|
272 (36%)
|
318 (42%)
|
8 (23%)
|
68 (9%)
|
Pump (deep well)
|
52 (4%)
|
165 (5%)
|
28 (6%)
|
98 (7%)
|
26 (3%)
|
45 (4%)
|
0
|
22 (3%)
|
Collect from river/rain
|
11 (1%)
|
135 (4%)
|
8 (2%)
|
56 (4%)
|
0
|
4 (0%)
|
3 (9%)
|
75 (10%)
|
Toilet/ septic tank in home
|
|
|
|
|
|
|
|
|
Yes
|
558 (45%)
|
590 (18%)
|
205 (45%)
|
300 (23%)
|
348 (46%)
|
348 (21%)
|
5 (14%)
|
26 (4%)
|
Latrine in yard
|
|
|
|
|
|
|
|
|
Yes
|
577 (46%)
|
2456 (75%)
|
314 (68%)
|
1227 (93%)
|
228 (30%)
|
523 (43%)
|
35 (100%)
|
706 (98%)
|
*The sample of households in Eldoret, Kenya is smaller than the other two communities as random sampling was switched to purposeful sampling midway through data collection to ensure a higher sample of LPG households available for subsequent phases of the CLEAN-Air(Africa) study. Note: variables for some countries do not add up to total sample size due to missing data or elimination of variable categories for brevity.
Households Cooking with LPG
Over half (52%, n=1,458) of households cooking with LPG used it as a primary fuel; very few (4%, n=109) exclusively cooked with LPG and 44% (n=1,263) used LPG as a secondary fuel (Table 2). In Obuasi, two-thirds of households reported using LPG as a primary fuel (67%; n=679), compared with one-third (37%; n=316) of households in Eldoret; in Mbalmayo LPG was used roughly equally as a primary and secondary fuel (48%; n=463). LPG was most frequently stacked with wood in Mbalmayo, and charcoal in Eldoret and Obuasi (Figure 2).
Figure 2. Most common primary, secondary (and tertiary) cooking fuel combinations by community. For brevity, only the most common fuel combinations (>35 households) were included. Among study households, there were nearly 200 different cooking fuel combinations.
Nearly half (47%) of households primarily cooking with LPG said it was not always available for purchase (Table 2); more than double those exclusively cooking with LPG (21%)). LPG consumption varied substantially from 0.75-67.0 kg/capita/yr. Median LPG consumption was 14.4 kg/capita/yr [IQR:10.4,24.0] in Eldoret, Kenya, 20.0 kg/capita/yr [IQR:15.0,30.0] in Mbalmayo, Cameroon and 23.2 kg/capita/yr [IQR:14.5,36.0] in Obuasi, Ghana. Mean cost of cylinder refills was lowest among households exclusively cooking with LPG ($0.99 USD/kg (SD:0.50)) and highest among households using LPG as a secondary fuel ($1.27 USD/kg (SD:0.67)).
In Eldoret, 72% of participants cooking exclusively with LPG were 10 minutes or less from a retailer compared with 47% and 36% of households using LPG as a primary or secondary fuel, respectively. Having an LPG retail point within walking distance was six times more common among households using LPG exclusively (61%) than those using LPG as a secondary fuel (11%).
Table 2. LPG usage characteristics among households reporting exclusive, primary or secondary use of LPG (n=2,830)
|
Overall
(N=2,830)
|
Mbalmayo, Cameroon
(N=958)
|
Obuasi,
Ghana
(N=1,020)
|
Eldoret,
Kenya
(N=852)
|
|
Exclusive
(N=109)
|
Primary
(N=1,458)
|
Secondary
(N=1,263)
|
Primary
(N=463)
|
Secondary
(N=495)
|
Exclusive
(N=77)
|
Primary
(N=679)
|
Secondary
(N=264)
|
Exclusive
(N=32)
|
Primary
(N=316)
|
Secondary
(N=504)
|
Unavailability of fuel
|
|
|
|
|
|
|
|
|
|
|
|
Always
available
|
86 (79%)
|
779 (53%)
|
613 (49%)
|
193 (42%)
|
229 (46%)
|
55 (71%)
|
345 (51%)
|
174 (66%)
|
31 (97%)
|
241 (76%)
|
210 (42%)
|
<4 times/yr
|
12 (11%)
|
396 (27%)
|
321 (25%)
|
116 (25%)
|
129 (26%)
|
11 (14%)
|
225 (33%)
|
68 (26%)
|
1 (3%)
|
55 (17%)
|
124 (25%)
|
4-12 times/yr
|
8
(7%)
|
124 (9%)
|
170 (13%)
|
43
(9%)
|
54
(11%)
|
8
(10%)
|
64
(9%)
|
13
(5%)
|
0
|
17
(5%)
|
103 (20%)
|
>12 times/yr
|
3
(3%)
|
79
(5%)
|
102
(8%)
|
34
(7%)
|
32 (6%)
|
3
(4%)
|
42
(6%)
|
8
(3%)
|
0
|
3
(1%)
|
62 (12%)
|
Don’t know
|
0
|
80
(5%)
|
57
(5%)
|
77 (17%)
|
51
(10%)
|
0
|
3
(0%)
|
1
(0%)
|
0
|
0
|
5 (1%)
|
Usage (# days previous wk)
|
|
|
|
|
|
|
|
|
|
|
|
0
|
5
(5%)
|
66
(5%)
|
274 (22%)
|
24
(5%)
|
125 (25%)
|
5 (6%)
|
35
(5%)
|
39 (15%)
|
0
|
7
(2%)
|
110 (22%)
|
1-3
|
18 (17%)
|
105
(7%)
|
179 (14%)
|
30
(6%)
|
68
(14%)
|
17 (22%)
|
65 (10%)
|
44 (17%)
|
1
(3%)
|
10
(3%)
|
67 (13%)
|
4-6
|
8
(7%)
|
190 (13%)
|
148 (12%)
|
89 (19%)
|
68
(14%)
|
8 (10%)
|
89 (13%)
|
47 (18%)
|
0
|
12
(4%)
|
33
(7%)
|
7
|
78 (72%)
|
1079 (74%)
|
629 (50%)
|
304 (66%)
|
208 (42%)
|
47 (61%)
|
490 (72%)
|
134 (51%)
|
31 (97%)
|
285 (90%)
|
287 (57%)
|
Years cooking with LPG
|
|
|
|
|
|
|
|
|
|
|
|
<1 yr
|
12 (11%)
|
112 (8%)
|
158 (13%)
|
14 (3%)
|
24 (5%)
|
3 (4%)
|
12 (2%)
|
8 (3%)
|
8 (25%)
|
31 (10%)
|
71 (14%)
|
1-2 yr
|
40 (37%)
|
437 (30%)
|
348 (28%)
|
51 (11%)
|
43 (9%)
|
4 (5%)
|
16 (2%)
|
10 (4%)
|
8 (25%)
|
45 (14%)
|
105 (21%)
|
2-5 yr
|
11 (10%)
|
57 (4%)
|
103 (8%)
|
85 (18%)
|
85 (17%)
|
18 (23%)
|
121 (18%)
|
64 (24%)
|
7 (22%)
|
100 (32%)
|
139 (28%)
|
5-10 yr
|
21 (19%)
|
529 (36%)
|
333 (26%)
|
93 (20%)
|
123 (25%)
|
32 (42%)
|
273 (40%)
|
107 (41%)
|
8 (25%)
|
71 (22%)
|
118 (23%)
|
>10 yr
|
25 (23%)
|
306 (21%)
|
288 (23%)
|
205 (44%)
|
194 (39%)
|
20 (26%)
|
257 (38%)
|
75 (28%)
|
1 (3%)
|
67 (21%)
|
64 (13%)
|
Cylinder size
|
|
|
|
|
|
|
|
|
|
|
|
6 kg
|
56 (51%)
|
457 (31%)
|
439 (35%)
|
6
(1%)
|
7
(1%)
|
28 (36%)
|
212 (31%)
|
20
(8%)
|
28 (88%)
|
239 (76%)
|
412 (82%)
|
9 kg
|
4
(4%)
|
18
(1%)
|
9
(1%)
|
0
|
0
|
4
(5%)
|
18
(3%)
|
9
(3%)
|
0
|
0
|
0
|
12.5 kg
|
1
(1%)
|
464 (31%)
|
466 (37%)
|
442 (95%)
|
462 (93%)
|
1 (1%)
|
22
(3%)
|
4
(2%)
|
0
|
0
|
0
|
13 kg
|
4
(4%)
|
79
(6%)
|
71
(6%)
|
0
|
0
|
0
|
8 (1%)
|
0
|
4
(12%)
|
71 (22%)
|
71 (14%)
|
14.5 kg
|
42 (38%)
|
292 (20%)
|
60
(6%)
|
0
|
0
|
42 (52%)
|
404 (59%)
|
60 (30%)
|
0
|
0
|
0
|
Consumption
(kg/capita/yr) (Median (IQR)*
|
29.0 [7.2, 18.8]
|
20.0
[13.6, 29.0]
|
12.0
[7.2, 18.8]
|
20.0
[15.0, 30.0]
|
12.5
[9.4, 20.0]
|
36.0
[23.2, 58.0]
|
23.2
[14.5, 36.0]
|
23.2
[12.0, 34.8]
|
24.0
[14.0, 36.0]
|
14.4
[10.4,
24.0]
|
9.0
[6.0,
14.4]
|
Refill cost per kg (USD) (Mean (SD))
|
0.99 (0.50)
|
1.05 (0.59)
|
1.27 (0.67)
|
1.03 (0.18)
|
1.03 (0.15)
|
0.77 (0.24)
|
0.85 (0.65)
|
1.20 (1.73)
|
1.52 (0.56)
|
1.56 (0.56)
|
1.52 (0.38)
|
Travel time to refill point(min)
|
|
|
|
|
|
|
|
|
|
|
|
Home
delivery
|
11 (10%)
|
103 (7%)
|
48
(4%)
|
0
|
0
|
11 (14%)
|
93 (14%)
|
43 (16%)
|
0
|
10
(3%)
|
5
(1%)
|
1-10
|
38 (35%)
|
390 (27%)
|
349 (28%)
|
133 (29%)
|
133 (27%)
|
15 (19%)
|
110 (16%)
|
37 (14%)
|
23 (72%)
|
147 (47%)
|
179 (36%)
|
11-20
|
20 (18%)
|
437 (30%)
|
398 (32%)
|
171 (37%)
|
171 (35%)
|
14 (18%)
|
168 (25%)
|
60 (23%)
|
6
(19%)
|
98 (31%)
|
167 (33%)
|
21-30
|
23 (21%)
|
349 (24%)
|
363 (29%)
|
114 (25%)
|
141 (28%)
|
20 (26%)
|
185 (27%)
|
87 (33%)
|
3
(9%)
|
50 (16%)
|
135 (27%)
|
30+
|
17 (16%)
|
162 (11%)
|
72
(6%)
|
30
(6%)
|
24
(5%)
|
17 (22%)
|
123 (18%)
|
37 (14%)
|
0
|
9
(3%)
|
11
(2%)
|
Transportation mode for refill
|
|
|
|
|
|
|
|
|
|
|
|
Motorbike
|
12 (11%)
|
593 (41%)
|
804 (64%)
|
419 (90%)
|
452 (91%)
|
0
|
12
(2%)
|
3
(1%)
|
12 (38%)
|
162 (51%)
|
349 (69%)
|
Car
|
32 (29%)
|
363 (25%)
|
167 (13%)
|
15
(3%)
|
6
(1%)
|
32 (42%)
|
310 (46%)
|
104 (39%)
|
0
|
38 (12%)
|
57 (11%)
|
On foot
|
32 (29%)
|
210 (14%)
|
122 (10%)
|
12
(3%)
|
11
(2%)
|
12 (16%)
|
119 (18%)
|
56 (21%)
|
20 (62%)
|
79 (25%)
|
55 (11%)
|
Public
transport
|
22 (20%)
|
172 (12%)
|
85
(7%)
|
2
(0%)
|
0
|
22 (29%)
|
145 (21%)
|
58 (22%)
|
0
|
25
(8%)
|
27
(5%)
|
Home delivery
|
11 (10%)
|
103 (7%)
|
48
(4%)
|
0
|
0
|
11 (14%)
|
93 (14%)
|
43 (16%)
|
0
|
10
(3%)
|
5
(1%)
|
Number of cylinders owned
|
|
|
|
|
|
|
|
|
|
|
|
1
|
77 (71%)
|
976 (67%)
|
1001 (79%)
|
364 (79%)
|
403 (81%)
|
46 (60%)
|
366 (54%)
|
146 (55%)
|
31 (97%)
|
246 (78%)
|
452 (90%)
|
2
|
25 (23%)
|
353 (24%)
|
189 (15%)
|
71 (15%)
|
57 (12%)
|
24 (31%)
|
227 (33%)
|
93 (35%)
|
1
(3%)
|
55 (17%)
|
39
(8%)
|
3+
|
7
(6%)
|
111 (8%)
|
40
(3%)
|
12
(3%)
|
9
(2%)
|
7
(9%)
|
86 (13%)
|
25 (9%)
|
0
|
13
(4%)
|
6
(1%)
|
Number of stove burners
|
|
|
|
|
|
|
|
|
|
|
|
1
|
58 (53%)
|
460 (32%)
|
536 (42%)
|
4
(1%)
|
10
(2%)
|
31 (40%)
|
242 (36%)
|
129 (49%)
|
27 (84%)
|
214 (68%)
|
397 (79%)
|
2
|
10
(9%)
|
339 (23%)
|
308 (24%)
|
218 (47%)
|
223 (45%)
|
8
(10%)
|
60
(9%)
|
24
(9%)
|
2
(6%)
|
61 (19%)
|
61 (12%)
|
3 or more
|
41 (38%)
|
641 (44%)
|
385 (30%)
|
226 (49%)
|
236 (48%)
|
38 (49%)
|
377 (56%)
|
111 (42%)
|
3
(9%)
|
38
(12%)
|
38
(8%)
|
Time since last stove purchase
|
|
|
|
|
|
|
|
|
|
|
|
<2 years
|
43 (54%)
|
645 (56%)
|
502 (47%)
|
225 (57%)
|
183 (45%)
|
34 (72%)
|
321 (73%)
|
126 (75%)
|
9
(28%)
|
99 (32%)
|
193 (39%)
|
3-4 years
|
17 (22%)
|
244 (21%)
|
236 (22%)
|
114 (29%)
|
104 (26%)
|
4
(9%)
|
69 (16%)
|
20 (12%)
|
13 (41%)
|
61 (19%)
|
112 (23%)
|
5-6 years
|
10 (13%)
|
134 (12%)
|
163 (15%)
|
35
(9%)
|
72 (18%)
|
7
(15%)
|
46 (10%)
|
18 (11%)
|
3
(9%)
|
53 (17%)
|
73 (15%)
|
7+ years
|
9
(11%)
|
130 (11%)
|
167 (16%)
|
24
(6%)
|
46 (11%)
|
2
(4%)
|
5
(1%)
|
3
(2%)
|
7
(22%)
|
101 (32%)
|
118 (24%)
|
*Annual per capita consumption is a derived variable obtained by multiplying cylinder size (kg) by self-reported number of annual refills
The relationship between the proportion of households reporting LPG as a primary fuel and family size was modified by the number of LPG stove burners. Only 10% of primary LPG households with a large family size (≥7 members) used a single-burner stove, compared with 50% of the smallest households (1-2 members) (Figure 3). A monotonically increasing association existed between the proportion of households primarily cooking with LPG and proportion using multi-burner stoves among households with more than four members.
Figure 3. Proportion of households cooking with LPG as a primary or secondary fuel by number of stove burners, stratified by number of family members
Modeling of LPG as a primary or secondary fuel choice
The final multivariable model modestly characterized (pseudo R2marginal=0.42; AUC=0.82) primary versus secondary use of LPG for cooking (Table S2). Demographics (R2marginal=0.11) and LPG supply-related factors (R2marginal=0.10) explained a higher proportion of model variability than SES (R2marginal=0.03) (Table S2). Households with 1-2 members had more than twice the predicted probability (89% (95%CI: 79,95)) of primarily using LPG than households with 7-8 family members (39% (95%CI: 24,56)) (Figure 4). Lower availability of LPG and higher refill costs were associated with a lower predicted probability of primary use of the fuel in a monotonically decreasing manner (Figure 4). Specifically, 76% (95%CI: 60,87) of households reporting a refill cost of <$0.86 USD/kg were predicted to use LPG as a primary fuel, compared with 65% (95%CI: 51,78), 58% (95%CI: 42,72) and 45% (95%CI: 28,62), of households reporting a cylinder refill cost of $0.86-1.00USD/kg, $1.01-1.10USD/kg and >$1.10USD/kg, respectively.
Figure 4. Average-adjusted predicted probabilities of using LPG as a primary versus secondary cooking fuel stratified by community. All probabilities account for quantitative covariates centered at their mean (all covariates listed in Table S4 in Supplement).
Modeling of Annual Per Capita LPG Consumption
Half (R2marginal=0.49; cross validation (CV) R2=0.39) of the variability in LPG consumption was explained by covariates included in the final model (root mean square error (RMSE)=0.52 kg/capita/yr; CV RMSE=0.54 kg/capita/yr) (Table S3). Household demographics (R2marginal=0.31) explained significantly times more of this variability than household SES (R2marginal=0.0). Households with 3-4 members consumed an average of 16.4 kg/capita/yr (95%CI: 13.5,19.8), nearly 13 kg/capita/yr less than households of 1-2 individuals (29.1 kg/capita/yr (95%CI: 24.0,35.2)) (Table S5).
Households using a double-burner or triple-burner LPG stove consumed an average of 8.2 kg/capita/yr (95%CI: 6.4,10.3) and 6.1 kg/capita/yr (95%CI: 4.8,7.5), respectively, more LPG than households with single-burner stoves, irrespective of SES and family size (Figure 5). Households exclusively cooking with LPG consumed 2.4 kg/capita/yr (95%CI: 1.2,3.8) more than households that stacked LPG with another fuel (Table S5).
Figure 5. Average-adjusted annual per capita LPG consumption (kg), stratified by community. Per capita consumption is presented with covariates centered at their mean (all covariates listed in Table S5 in Supplement).
Participants that took 11-20 minutes, 21-30 minutes or >30 minutes to travel to LPG retailers consumed an average of 1.0 kg/capita/yr (95%CI: 0.0,1.9), 1.4 (95%CI: 0.5,2.3) and 1.6 kg/capita/yr (95%CI: 0.0,3.0) less than those who could reach an LPG retailer in under 11 minutes (Table S4). In addition, households reporting the lowest costs for refilling their LPG (<$0.86USD/kg) consumed 1.4 (95%CI: 0.2,2.6), 2.3 (95%CI: 0.8,3.7) and 4.9 (95%CI: 3.2,6.5) kg/capita/yr more than participants reporting higher refill costs of $0.86-1.00USD/kg, $1.01-1.10USD/kg and >$1.10USD/kg, respectively.
Households Exclusively Cooking with Polluting Fuels
Among households exclusively cooking with polluting fuels (n=2,685), nearly half (47%, n=1,248) reported having previously cooked with LPG (Table S6); the proportion varied nearly three-fold by community (Obuasi:63% (n=612), Mbalmayo:48% (n=399), Eldoret:24% (n=237)). Only 10% (n=272) of households cooking exclusively with polluting fuels indicated being satisfied with their current cooking fuel.
Inability to afford the upfront costs of purchasing LPG stoves/equipment was the dominant reason (70%; n=1,889) reported for not currently cooking with LPG (Figure 6). High refill costs were cited as a barrier for LPG use by twice as many households previously cooking with LPG (37%) as those that had not (19%) (Table S6). Concerns over LPG safety were reported by 18% (n=470) of households not currently using LPG; this concern was highest among households in Obuasi (30%; n=292); the proportion was twice as high as in Mbalmayo (14%; n=117) and five times higher than in Eldoret (6%; n=61).
Figure 6. Reasons for not cooking with LPG among households exclusively cooking with polluting fuels (N=2,685)