Household Cooking Fuel Use among Residents of a Sub-Urban Community in Nigeria: Implications for Indoor Air Pollution

Abstract

Objective:

The aim of this study is to assess the types of household cooking fuel used by residents of Isiohor community in Edo State, Nigeria.

Materials and Methods:

This descriptive cross-sectional study was conducted among 133 household heads or their representatives in Isiohor Community in Edo State, Nigeria. Data collection was by means of a structured interviewer administered questionnaire.

Results:

Half (50.3%) of the households studied were made up of 4-6 persons living in them. Sixty-two (46.6%) respondents had tertiary level of education and a third 44 (33.1%) earned between 21,000 and 30,000 naira (150-200 dollars) monthly. Forty six (34.6%) and 27 (20.3%) respondents live in passage houses and flats respectively. Two thirds (68.4%) of the respondents cook their food indoors. The predominant household cooking fuels used by the respondents were cooking gas (51.1%), Kerosene (45.9%), vegetables (25.6%) and firewood (14.3%). Majority 106 (79.7%) had poor knowledge of the health effects of prolonged exposure to smoke arising from indoor cooking. There was a statistically significant association between the occupation of the respondents and the type of household cooking fuel used (p=0.002).

Conclusion:

The use of unclean indoor cooking fuel was high among the residents of Isiohor community in Edo State, Nigeria. Also, there was poor knowledge of the health effects of prolonged exposure to smoke from unclean cooking fuel among the respondents and this has serious implications for indoor air pollution. There is an urgent need for health/hygiene education on the health effects of use of unclean indoor cooking fuel among these residents. There is also need for use of clean/green cooking stoves and construction of exhaust ventilation pipes in these households.

Introduction

Energy is essential to meet most of the basic needs of the people such as cooking, boiling water, lighting and heating. It is also necessary for good health if the sources are clean, as this reduces exposure to health damaging pollutants and the consequent implications [1]. In Nigeria as in many developing countries, the high costs of modern cooking energy such as Liquid Petroleum Gas (LPG) and electricity and their cooking stoves are major constraints for household fuel preferences [2]. This is not only compounded by the poor economic situation but also by the epileptic and poor electricity supply. These have resulted in the use of fossil and solid fuel (biomass and coal) as major sources of cooking energy by the people [3]. The Nigerian Demographic and health Survey (NDHS) of 2008 showed that three-quarters of all households in Nigeria are using solid fuels for cooking and the use of solid fuel is moderate in urban areas (45.0%) but very high in rural areas (90.0%) [4]. Among the households that reported the use of solid fuel for cooking, a majority (94.0%) used an open fire/stove without a chimney or hood, 40.0% of then cook inside their houses, while one-quarter (25.0%) cook outdoors. The percentage of households that cook in their dwelling is higher in urban areas (43.0%) than in rural areas (38.0%) [4, 5].

Diseases due to indoor air pollution from cooking remain a leading cause of respiratory morbidity and mortality worldwide, in sub-Saharan Africa and in Nigeria in particular [4, 6, 7]. Globally, more than three billion people still burn wood, dung, coal and other traditional fuels inside their homes and the resultant indoor air pollution is responsible for more than 1.5 million deaths a year - mostly of young children and their mothers who spend most of their time at home and in the kitchen [8]. Also, millions of people die from acute infections of the lower respiratory tract, chronic obstructive pulmonary diseases (COPD), tuberculosis, pneumonia (especially in children who are exposed to these dangerous gases from an early age), and other diseases such as asthma, lung cancer, non communicable diseases such as heart disease, stroke, cataract, and other cancers [4, 5, 8]. These are significant obstacles towards the achievement of Millennium Development Goals (MDG) 4, 5 and 6 [7, 8].

In many developing countries, young children are often carried on their mother’s back during indoor cooking. Consequently, they spend many hours breathing smoke that contain these health damaging pollutants from early infancy [1, 8]. This is responsible for the nearly one million deaths in children under five years of age every year [1]. The exposure of the developing embryo to indoor air pollution may also contribute to perinatal mortality and low birth weight, a major risk factor for a variety of diseases during childhood [1]. In addition kitchen fires and kerosene wick lamps are a major cause of burns for infants and toddlers. All these increases child mortality and morbidity in the long run hindering the achievement of MDG 4 [1]. Women, who are usually in charge of cooking, are most at risk of chronic respiratory problems, such as COPD due to indoor air pollution that contributes to worsening respiratory health, in particular among young mothers who spend at least 3-7 hours daily close to unclean household cooking fuel. The Exposure of these women to small particulate matter with a diameter of 10 microns (PM10) or less (many times above the generally accepted guideline limits of 150 µg/m³) and to carcinogens that are able to penetrate deep into the lungs results in health-damaging effects [1, 8]. Thus this study was aimed at assessing the types of household cooking fuel used by residents of Isiohor community in Edo State, Nigeria, with a view to understanding the health implications for indoor air pollution.

Materials and Methods

Study site and population

The study was carried out in Isiohor community, in Ovia North East Local Government Area of Edo State, Nigeria [9]. Isiohor community is located in the suburb of Benin City, along Benin-Lagos expressway and adjacent to the Ugbowo campus of the University of Benin, Benin City, Nigeria. It is bounded to the North by Ekosodin community, to the East by Ugbowo community, to the South by Ohonre community and to the West by Iguosa community [9, 10]. The study population was made up of all the household heads or their representatives in Isiohor community as at the time of the study.

Data collection

Data were collected using a structured interviewer administered questionnaire with open and closed ended questions. Information sought from the respondents included socio-demographic data, types of household cooking fuel and knowledge of the effects of the use of household cooking fuel on health. Assessment of knowledge comprised of questions on exposure to solid fuel smoke, knowledge of symptoms of ill health due to such exposure and hospitalization as a result of such exposure. The total number of questions for assessing knowledge was six. A score of 1 was assigned to each correct answer while 0 was assigned to incorrect answers. The total score for knowledge was 6. A score of 0-3 was considered poor knowledge and a score of 4-6 was considered good knowledge. In this study clean household cooking fuel comprises cooking gas and electricity while unclean household cooking fuel comprises use of kerosene, sawdust, firewood, charcoal and vegetables.

Two trained research assistants who were Community Health Extension Workers (CHEW) from the Department of Community Health, UBTH, Benin City assisted with data collection. The UK Registrar General’s classification was used to categorize the occupation of the respondents into skill levels (professional, managerial, skilled manual, semi skilled and unskilled) [11].

Statistical analysis

The questionnaires were screened for completeness by the researchers and coded. Data were entered into and analysed using the Statistical Package for Scientific Solution (SPSS) version 16 statistical software(SPSS Inc, Chicago, IL, USA). Qualitative data such as, occupational and educational statuses were presented as percentages. Fishers exact test was used to test the association between socio-demographic characteristics and types of cooking fuel used by the respondents with the level of significance set at p-value less than 0.05.

Ethical considerations

Approval to carry out the study was obtained from the Ethics and Research committee of the University of Benin Teaching Hospital. Permission was sought from the head of Isiohor community. Informed consent was obtained from each of the respondents. Confidentiality and privacy of the respondents was respected during the interviews. Health education of the respondents on effects of indoor air pollution from use of unclean sources of cooking fuel was carried out at the end of data collection.

Results

A total of 133 household heads or their representatives were interviewed. Table 1 shows the socio-demographic characteristics of the households and respondents. Over half (50.3%) of the households studied were made up of 4-6 persons, less than a quarter 29 (21.8%) of the households were made up of 7-9 persons and 24 (18.0%) of the households were made of 1-3 persons. Forty six (34.6%) and 27 (20.3%) respondents live in passage houses and flats respectively. Over two thirds (72.9%) of the respondents cooked their food indoors. Above one third 46 (34.6%) of the respondents were managers, less than a quarter 40 (30.1%) of the respondents were skilled manual workers and 31 (23.3%) of the respondents were professional workers. Sixty-two (46.6%) of the respondents had tertiary level of education while 43 (32.3%) had secondary level of education and 23 (17.2%) had primary level of education. Close to a third 44 (33.1%) of the respondents earned between 11, 000 and 20,000 naira (70-135 dollars) monthly and only 17 (12.8%) earned above 30000 naira (200 dollars and above).

Table 1.

Socio-demographic and household characteristics of respondents

Variable	Frequency (n=133)	Percent
Household size
1–3	24	18.0
4–6	67	50.3
7–9	29	21.8
10–12	10	7.6
13–15	3	2.3
Type of house
Flat	27	20.3
Self-contain	29	21.8
One room	31	23.3
Passage	46	34.6
Location of kitchen
Indoors	97	72.9
Outdoor	36	27.1
Occupation of household head
Professional	31	23.3
Manager	46	34.6
Skilled non-manual	8	6.0
Skilled manual	40	30.1
Unskilled	8	6.0
Level of Education of household head
None	5	3.9
Primary	23	17.2
Secondary	43	32.3
Tertiary	62	46.6
Income of household head (in Naira)
1000–10000	48	36.1
11000–20000	44	33.1
21000–30000	24	18.0
>30000	17	12.8

The predominant household cooking fuels used by the respondents were cooking gas 68 (51.1%), Kerosene 61 (45.9%), vegetables 34 (25.6%) and firewood 19 (14.3%). Others included use of electricity18 (13.5%) and Charcoal 4 (3.0%) (Table 2).

Table 2.

Types of household cooking fuel used by respondents

Types cooking fuel	Yes Freq (%)	No Freq (%)
Cooking gas*	68 (51.1)	65 (48.9)
Kerosene	61 (45.9)	72 (54.1)
Vegetable	34 (25.6)	99 (74.4)
Firewood	19 (14.3)	114 (85.7)
Electricity*	18 (13.5)	115 (86.5)
Charcoal	4 (3.0)	129 (97.0)
Sawdust	3 (2.3)	130 (97.7)

^*Clean household cooking fuel

The respondents’ knowledge of the health effect of exposure to indoor air pollution is shown in Figure 1. Majority, 116 (87.2%) of the respondents had poor knowledge of the health effects of prolonged exposure to air pollution from indoor cooking, while less than a fifth 17 (12.8%) of the respondents had good knowledge of the health effects due to prolonged exposure to indoor air pollution.

Figure 1.

Knowledge of the effects of household cooking energy on health among the respondents.

TTHA: tension-type headache; ETTHA: epizodic tension-type headache; CTTHA: cronic tension-type headache

Table 3 shows the association between socio-demographic characteristics of the respondents and types of household cooking fuel used in the community. There was a statistically significant association between the occupation of the respondents and the use of household cooking fuel. A higher proportion of professionals 14 (45.2%) and managers 18 (39.1%) making use of clean household cooking fuel compared to the skilled manual 1(12.5%) workers and the unskilled 0 (0.0%) workers (p=0.002). Although a higher proportion of respondents with tertiary level of education (37.1%) and those with monthly income of between 11,000 and 20,000 naira used clean cooking fuel, there was no statistically significant association between the level of education (p=0.153) and monthly income (p=0.564) of the respondents and the type of household cooking fuel used by them.

Table 3.

Sociodemographic characteristics of respondents and type of household cooking fuel

Variables	Type of household cooking fuel (n=133)
	Clean n (%)	Unclean n (%)	Fisher’s Exact	p value
Level education of household heads
None	0 (0.0)	5 (100.0)	4.906	0.158
Primary	6 (26.1)	17 (73.9)
Secondary	9 (20.9)	34 (79.1)
Tertiary	23 (37.1)	39 (62.9)
Occupation of household heads
Professional	14 (45.2)	17 (54.8)	15.702	0.002*
Manager	18 (39.1)	28 (60.9)
Skilled manual	1(12.5)	7 (87.5)
Semi skilled	5 (12.5)	35 (87.5)
Unskilled	0 (0.0)	8 (100.0)
Income of household heads in Naira
1000–10000	15 (31.3)	33 (68.7)	2.095	0.564
11000–20000	14 (31.8)	30 (68.2)
21000–30000	4 (16.7)	20 (83.3)
>30000	5 (29.4)	12 (70.6)

^*Statistically significant

Discussion

This study showed that more than two thirds of the household studied had sizes of 4 and above. The use of unclean cooking fuel such as kerosene, firewood and vegetables was prevalent in the study population. However, there was poor knowledge of the health effects of prolonged exposure to indoor air pollution arising from cooking fuels among the respondents.

The findings of a household size of between 4 and 6 by half of the households in this study may have been due to the fact that almost a third and over two fifth of the respondents had secondary and tertiary level of education respectively. This may have influenced their family planning practices, thus limiting their family size within the recommended Nigerian average. Another possible reason could be the nearness of Isiohor community to UBTH, which might have influenced their family planning practices positively. This is similar to findings from NDHS that puts Nigeria average family size at 5.4 [5]. Smaller family sizes have been found to improve the overall well being of the family and Community.

More of the respondents live in passage houses. This may have been influenced by the poor economic situation in Nigeria that restricts the acquisition of accommodation like flats and self-contain accommodation by majority of the people. This is also supported by findings from this study in which about a third of the respondents earned between 11,000 and 20,000 naira monthly (70–135 dollars).

The indoor location of kitchen by majority of the respondents might not be unconnected to living in a sub-urban community and the influences of urbanization and development. Urbanization and development in Nigeria has resulted in the construction of passage houses, self-contain apartments and flats with indoor built-in kitchens. This finding is also similar to findings from other studies and survey [4, 5] in which more of the respondents cooked indoors and as they had their kitchen located indoors [12, 13]. This finding is compounded by the use of unclean household cooking fuel by a greater proportion of the respondents in this study. The resultant effect is exposure to high concentrations of health-damaging pollutants such as particulate matter and other toxic elements that poses substantial health risks to the respondents and other members of these households especially the mothers and children who are most exposed and vulnerable.

Another compounding factor for negative implication of indoor air pollution as a result of use of unclean household cooking fuel by a greater proportion of the households in this study is the poor knowledge of the health effect of this practice among the respondents. This finding was not consistent with findings from a study in Ilorin, Nigeria in which most of the respondents interviewed were aware of indoor air pollution and knowledgeable about is health effects [14]. The lack of knowledge of the health effects of using unclean cooking fuel will not only increase exposure and the damaging health effects but will also hinder the use protective measures. This will in the long run result in acute and chronic respiratory symptoms and disease conditions such as cough, wheezing, catarrh, chronic obstructive pulmonary diseases and asthma etc. This finding is similar to findings from studies done in Nigeria [12–16] and India [6] in which respondents exposed to emissions from using firewood and kerosene as forms of cooking fuel experienced resultant respiratory damaging health effects. There is therefore need for urgent health education on the damaging-health effects of indoor air pollution among the residents of Isiohor community.

The level of education of the heads of households in this study was not statistically associated with type of cooking fuel used in the households. This was not surprising, considering the fact that there is poor and epileptic electricity supply and this is compounded by the high cost of cooking gas in Nigeria [1, 17]. This may have accounted for the use of other forms of unclean cooking fuel which are believed to be cheaper and readily available for use. This finding was not consistent with findings from a study in Ilorin [14] and Ekiti [18] States, Nigeria in which more of the educated respondents made use of clean sources of cooking fuel such as electricity and cooking gas.

The level of income of the heads of these households was also not statistically associated with the type of household cooking fuel. Again, this was not surprising as over four fifth of the respondents earned less than 30,000 naira monthly (200 dollars) and might not be able to afford cooking gas and other types of clean household cooking fuel. This finding was in contrast with findings from other studies in Nigeria [12, 18] in which the use of clean household cooking fuel was associated with household income, the wealthier the household the more the use of clean cooking fuel. There is need for the introduction of other forms of cheaper clean household cooking fuel and their stoves that would be readily available and easy to use so as to reduce exposure to particulate matter and other forms gases due to indoor pollution.

The occupation of heads of households was statistically associated with type of cooking fuel used in the community, this might have been due to the fact that the professionals and managers may be more knowledgeable about the damaging health effects of unclean cooking fuel and this necessitated the use clean cooking fuel high up in the energy ladder. This finding was consistent with findings from the Ekiti study in which respondents with white collar jobs were more knowledgeable about the health effects of cooking fuels down the energy ladder and consequently made use of cleaner cooking fuel up the energy ladder [18]. Thus exposure to indoor air pollution from the combustion of unclean cooking fuels constitutes a significant public health hazard affecting predominantly poor households and communities in developing countries and this ultimately results in morbidity and mortality.

Although this study has highlighted a very important contributor of indoor air pollution among households in a sub-urban community in southern Nigeria, it is limited by the fact that the results obtained relied on responses by the respondents and thus may be prone to information bias.

In conclusion, the use of unclean indoor cooking fuel low in the energy ladder was high among residents of Isiohor community in Edo state, Nigeria. Also, there was poor knowledge of the health effects of prolonged exposure to smoke from unclean cooking fuel among the respondents. This calls for an urgent need for health/hygiene education on the health effects of use of unclean indoor cooking fuel among these residents, so as to reduce indoor air pollution in these households. Also, there is need for use of clean/green cooking stoves and construction of exhaust ventilation pipes in these household. These findings also underscore the need for further assessment of the concentration of household indoor air pollutants and respiratory function of household members in Isiohor community.