Socio-demographic characteristics
A total of 374 respondents were interviewed representing a response rate of 97.1%. The mean age of the respondents was 30.22 (SD±0.51), 95% CI [29.21-31.23]. More than half (55.62%, 208/374) had attained post-primary education (Table 1). The households comprised an average of 4 people. The majority of the cooking 90.11% (337/374), was done by the spouse of the household head.
Table 1: Socio-demographic characteristics of respondents of Kisneyi-Mugunu slum, Fort Portal City, Uganda
Variable
|
Category
|
Frequency N=374 (%)
|
Age category
|
Below 20
|
43 (11.5)
|
|
21-30
|
195 (52.14)
|
|
31-40
|
98 (26.2)
|
|
41-50
|
21 (5.61)
|
|
Above 50
|
17 (4.55)
|
Level of education
|
No formal education
|
27 (7.22)
|
|
Primary
|
139 (37.17)
|
|
Secondary
|
181 (48.40)
|
|
Tertiary
|
27 (7.22)
|
Religion
|
Anglican
|
100 (26.74)
|
|
Catholic
|
157 (41.98)
|
|
Muslim
|
73 (19.52)
|
|
Pentecostal
|
31 (8.29)
|
|
Seventh Day Adventist
|
13 (3.48)
|
Marital status
|
Living with partner
|
168 (44.92)
|
|
Single
|
134 (35.83)
|
|
Married
|
60 (16.04)
|
|
Widowed
|
7 (1.87)
|
|
Divorced
|
5 (1.34)
|
Person who usually does the cooking
|
Spouse of the household head
|
337 (90.11)
|
Another relative
|
21 (5.61)
|
Maid/ House helper
|
15 (4.01)
|
Do not cook at all
|
1 (0.27)
|
Cooking characteristics among households
More than three quarters (88.77%, 332/374) of the respondents used charcoal as the main type of fuel while less than 1% used LPG or electricity (Table 2). Respondents, on average, spent USD$0.6 (SD±0.02) on fuel daily. Above half, 51.87% (194/374) found the daily cost of the fuel acceptable while 28.61% (107/374) reported the daily price as not affordable. The households cooked an average of 2 meals a day and about 4.5 hours were spent cooking per day. More than half (63.37%, 237/374) did not have a separate room used as a kitchen (Table 2). Half 51.87% (194/374) did their cooking outdoors while 16.04% (60/374) usually cooked indoors. Cooking in a separate building outside the house was reported by 32.09% (120/374) of the households. Over half 57.23% (190/332) that used charcoal as the main type of fuel reported cooking from outdoors while 93.94% (31/33) of those that used wood reported cooking from a separate building outside the house.
Table 2: Cooking characteristics among households in Mugunu slum, Fort Portal City, Uganda
Variable
|
Category
|
Frequency N=374 (%)
|
The main type of cooking fuel
|
Charcoal
|
332 (88.77)
|
|
Electricity
|
1 (0.27)
|
|
Kerosene
|
3 (0.80)
|
|
LPG/cylinder gas
|
2 (0.53)
|
|
Straw/shrubs/grass
|
3 (0.80)
|
|
Wood
|
33 (8.82)
|
Affordability of fuel
|
Affordable
|
194 (51.87)
|
|
Not affordable
|
107 (28.61)
|
|
Very Affordable
|
73 (19.52)
|
Separate room as a kitchen
|
Yes
|
137 (36.63)
|
|
No
|
237 (63.37)
|
|
|
|
Location of cooking area
|
Inside the house
|
60 (16.04)
|
|
Outdoors
|
194 (51.87)
|
|
Separate building
|
120 (32.09)
|
Location of kitchen windows
|
Not close to the main entrance door
|
278 (74.33)
|
|
Close to the main entrance door
|
96 (25.67)
|
Fuel storage area
|
Inside the house
|
164 (43.85)
|
|
Outdoors
|
73 (19.52)
|
|
Separate building
|
137 (36.63)
|
Adequacy of cooking area ventilation
|
Not adequate
|
149 (39.84)
|
|
Adequate
|
225 (60.16)
|
Traditional cook stove
|
Yes
|
311 (83.16)
|
|
No
|
63 (16.84)
|
State of repair of the traditional stove (n=311)
|
Good
|
260 (83.60)
|
|
Not good
|
51 (16.40)
|
Improved cook stove
|
Yes
|
92 (24.60)
|
|
No
|
282 (75.40)
|
State of repair of Improved cook stove (n=92)
|
Good
|
83 (90.22)
|
|
Not good
|
9 (9.78)
|
Fuel biomass storage area protected from water ((n=368)
|
Yes
|
236 (64.13)
|
|
No
|
132 (35.87)
|
Fuel biomass damp (n=368)
|
No
|
211 (57.34)
|
|
Yes
|
157 (42.66)
|
Majority (74.33%, 278/374) of the households did not have a window close to the main entrance door, however, adequate ventilation of the cooking area was observed for 60.16% (225/374) of the households (Table 2). For those who cooked outdoors, the average cooking distance from the house's main entrance was 3.14±0.17 0m. The cooking time in the study was generally between 8:00 Am and 6:00 PM. Traditional portable and lightweight charcoal cookstoves made of metal with a ceramic liner and one fire per pot which are batch-fed were used by majority of households, 83.16% (311/374) and of these, 83.6% (265/311) were in a good work condition. Fuel was stored indoors by almost half (43.85%, 164/374) of the respondents and 36.63% (137/374) stored the fuel in a separate building outside the house. However, only 64.13% (236/368) reported that the biomass fuel was protected from rainwater while 157/368 (42.66% ) were found using damp biomass fuel (Table 2).
Predictors of PM2.5 and CO concentration
During the cooking time, the mean PM2.5 concentrations for the cooking and living area was 175.93±12.49 µg/m3 and 124.29±7.95 µg/m3 respectively (Table 3). These concentrations are higher than the WHO air quality guideline of 25μg/m3 for 24hr. The mean CO concentration during cooking time was 41.22ppm and 15.23ppm for the cooking and living area respectively. This was also above the 24hr WHO air quality guideline of 7ppm however it was below the 87ppm WHO 15 Minute Average. From an unpaired t-test, it was found that there was a statistically significant difference between PM2.5 and CO concentration in the cooking and living area (t=18.14, p ≤ 0.05) and (t=5.77 p ≤ 0.05).
Table 3: Mean concentration of PM2.5 and CO for the cooking and living area in households in Mugunu slum, Fort Portal City, Uganda
|
Cooking area
|
Living area
|
Cooking area
|
Living area
|
Mean
|
175.93
|
124.29
|
41.22
|
15.53
|
Std. Err.
|
12.49
|
7.95
|
3.31
|
1.70
|
[95% CI]
|
151.37 - 200.49
|
108.66 - 139.92
|
34.71 - 47.74
|
12.18 - 18.87
|
Cooking in a separate building outside the house resulted in the highest pollution with PM2.5 and CO of 176.13 µg/m3 and 46.86ppm, respectively (Table 4). Cooking outdoors also presented high levels of PM2.5 (162.58 µg/m3) and CO (44.37 ppm). Cooking with all fuel types presented with high concentrations of PM2.5 and CO for both the cooking and living areas for this informal settlement (Table 4). In the neighbouring village of Rwengoma, ambient air quality monitors [21] reported an average PM2.5 of 69.62 µg/m3 in the week during which this study air quality measurements were taken.
Table 4: Distribution of PM2.5 and CO by cooking area location in households in Mugunu slum, Fort Portal City, Uganda
|
PM 2.5 (µg/m3)
|
CO (ppm)
|
Location of cooking area
|
Mean (SD)
|
Mean (SD)
|
Indoors (n=60)
|
162.58 ± 11.79
|
44.37 ± 4.57
|
Outdoors (n=194)
|
166.66 ± 6.72
|
39.27 ± 2.49
|
Separate building outside the house (n=120)
|
176.13 ± 9.45
|
46.86 ± 3.12
|
At multivariate analysis cooking outdooors was associated with a 0.112 increment in PM2.5 concentrations in the cooking area (βcooking outdoors = 0.112 [95% CI: -0.069, 1.614; p= 0.033]) (Table 5) Considering majority of households cooked outdoors in this study,further analysis on cooking outdoors revealed that cooking with less polluting and moderately polluting fuel was associated with a 1.77 (β2 cooking outside* less polluting = -1.77(-3.355, -0.186) and 0.934 (β2 cooking outside* moderately polluting = -0.934 (-1.736, -0.133) decrement in PM2.5 respectively (Table 5). Cooking with moderately polluting fuel was associated with a 0.719 increment in CO concentrations (βmoderately polluting = 0.718 [95% CI: 0.084, 1.352; p= 0.027]) (Table 6) (in the living room.
Table 5: Adjusted regression coefficient for predictors of PM2.5 concentrations in the cooking and living area in households in Mugunu slum, Fort Portal City, Uganda
Variable
|
Cooking area
|
Living area
|
|
Coefficient (95% CI)
|
P-value
|
Coefficient (95% CI)
|
P-value
|
Adequate ventilation
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
-0.027(-0.213, 0.159)
|
0.78
|
-0.062(-0.224, 0.099)
|
0.47
|
Window close to the door
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
0.176 (-0.022, 0.374)
|
0.08
|
0.043 (-0.131, 0.215)
|
0.63
|
Damp fuel
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
0.112(-0.064, 0.289)
|
0.21
|
0.048 (-0.105, 0.202)
|
0.53
|
Cooking outside
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
0.112(0.069, 1.614)
|
*0.03
|
-0.024 (-0.201, 0.152)
|
0.76
|
Type of fuel category
|
|
|
|
|
Less polluting
|
0.272(-0.800, 1.345)
|
0.62
|
0.022( -0.600, 0.645)
|
0.95
|
Moderately polluting
|
-0.377(-1.115, 0.362)
|
0.32
|
0.031( -0.217, 0.27
|
0.81
|
Highly polluting
|
ref
|
|
ref
|
|
Cooking outside * Type of fuel category
|
|
|
|
|
Less polluting
|
-1.770(-3.355, -0.186)
|
*0.03
|
-
|
-
|
Moderately polluting
|
-0.934 (-1.736, -0.133)
|
*0.02
|
-
|
-
|
Highly polluting
|
ref
|
|
-
|
-
|
*p-value less than 0.05
Considering a 95% CI, a p-value ≤ 0.05 was considered to be statistically significant in this study
|
Table 6: Adjusted regression coefficient for variables associated with the concentration of CO in the cooking and living area in households in Mugunu slum, Fort Portal City, Uganda
Variable
|
Cooking area
|
Living area
|
|
Coefficient (95% CI)
|
P-value
|
Coefficient (95% CI)
|
P-value
|
Adequate ventilation
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
-0.124( -0.479,0 .231)
|
0.49
|
-0.258(-0.619, 0.102)
|
0.16
|
Window close to the door
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
0.283( -0.086, 0.652)
|
0.13
|
-.019( -0.401, 0.363)
|
0.92
|
Damp fuel
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
-0.086( -0.421, 0.249)
|
0.61
|
-0.0669(-0.402, 0.269)
|
0.69
|
Cooking outside
|
|
|
|
|
No
|
ref
|
|
ref
|
|
Yes
|
0.493( -1.454, 2.441)
|
0.62
|
-0.207(-0.596, 0.182)
|
0.30
|
Type of fuel category
|
|
|
|
|
Less polluting
|
1.697( -0.589, 3.982)
|
0.15
|
1.314(-0.034, 2.663)
|
0.06
|
Moderately polluting
|
0.427( -1.474, 2.328)
|
0.66
|
0.718( 0.084, 1.352)
|
*0.03
|
Highly polluting
|
ref
|
|
ref
|
|
Cooking outside * Type of fuel category
|
|
|
|
|
Less polluting
|
-1.608( -5.127, 1.912)
|
0.37
|
-
|
-
|
Moderately polluting
|
-0.129( -2.116, 1.858)
|
0.90
|
-
|
-
|
Highly polluting
|
ref
|
|
-
|
-
|
p-value less than 0.05
Considering a 95% CI, a p-value ≤ 0.05 was considered to be statistically significant in this study
|