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UNIVERSITY OF NAIROBI
COLLEGE OF BIOLOGICAL AND PHYSICAL SCIENCES
DEPARTMENT OF CHEMISTRY
INDOOR AIR POLLUTION: ANALYSIS OF EMISSIONS FROM VARIOUS
COOKING STOVES
By:
David Ng’ang’a
I20/I542/2011
A RESEARCH PROJECT SUBMITTED IN PARTIAL FULFILLMENT OF THE
BACHELOR OF SCIENCE DEGREE IN (CHEMISTRY) OF THE UNIVERSITY OF
NAIROBI

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DECLARATION
Declaration by student
I hereby declare that this project is my original work to the best of my knowledge and has
not been submitted to any other University for any award or academic purpose.
…………………………………………….……………………………
David Ng’ang’a
Supervisors’ Approval
I hereby confirm that this project has been written and submitted with my (our) approval
as the supervisor(s) and therefore approve it for submission to the University.
Prof. Kithinji .P. Jacob: ……………………….……………………………
Dr. Damaris N. Mbui: …………………………………………………….
Department of Chemistry, University of Nairobi

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DEDICATION
I dedicate this project:
To my Grandmother, Salome, who believed in me and everything I did and supported me all
through to the completion of my education.
To my Parents and siblings, who have stood by me and accorded me the love and support that
has always been my beacon of hope.
To all who made the completion of this project a success.
A big Thank you

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ACKNOWLEDGEMENT
I would first like to acknowledge Mr. Hesborn Nyangena and Justus Muoki for their support and
training on the Water Boiling test Protocol that made carrying out the tests required for this study
a success.
I would also like to extend my heartfelt gratitude to fellow undergraduate students John Julius
Mutua, Mercy Barasa, Dennis Sulwey, Violet Awuor, Michael Mwangi and the class of 2015 for
their co-operation and assistance in all stages of carrying out this research.
Last, but not least, I would like to extend my gratitude to the Department of Chemistry: the
Chairman and all the lecturers for their important role they have played in my education.
Above all, my greatest appreciation goes out to my supervisors Prof. J.P.Kithinji and Dr.
Damaris.N.Mbui for their expertise, guidance and supervision together with providing resources,
without which this research would not have reached its successful completion.

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TABLE OF CONTENT
DEDICATION.......................................................................................................................... 3
ACKNOWLEDGEMENT ........................................................................................................ 4
TABLE OF CONTENT............................................................................................................ 5
ABSTRACT.............................................................................................................................. 6
CHAPTER 1 ............................................................................................................................. 8
1.0. INTRODUCTION...............................................................................................................8
CHAPTER 2 ........................................................................................................................... 17
2.0. LITERATURE REVIEW........................................................................................................17
2.3. ILLNESS CAUSED BY IAP........................................................................................... 25
2.3.1. CHRONIC OBSTRUCTIVE PULMONARY DISEASE........................................................25
2.3.2. LUNG CANCER.................................................................................................................25
2.3.3. PNEUMONIA .......................................................................................................................25
CHAPTER 3 ........................................................................................................................... 27
3.0. METHODOLOGY.................................................................................................................27
3.1. APPARATUS AND REAGENTS........................................................................................27
3.2. TEST PROCEDURE..........................................................................................................27
CHAPTER 4 ........................................................................................................................... 33
4.0. RESULT AND DISCUSSION................................................................................................33
CHAPTER 5 ........................................................................................................................... 40
5.0. CONCLUSION AND RECOMMENDATIONS.......................................................................40
5.1. CONCLUSION......................................................................................................................40
5.2. RECOMMENDATIONS..........................................................................................................40
5.3. RELEVANCE OF FINDINGS................................................................................................41
References............................................................................................................................... 43

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LIST OF ABBREVIATIONS
ppm: Parts per million
CO: Carbon monoxide
WHO: World Health Organization
PM: Particulate matter
CO2: Carbon dioxide
Mg/m^3: Milligrams per meter cubed
g/litre: Grams per Litre
g: grammes
g/min: Grams per Minute
min: Minutes
KPT: Kitchen Performance Test
CCT: Controlled Cooking Test

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ABSTRACT
Indoor air pollution (IAP) from biomass cook stoves seriously affects human health worldwide. Most of
the biomass stoves in use are traditional cook stoves, which produce toxic emissions and are inefficient.
This has prompted the introduction of improved stoves which enable families to meet their household
cooking and heating requirements without the risks posed by traditional stoves. The purpose of this study
was to investigate the stove performance (in terms of IAP levels and efficiency) of an improved wood
stove (here referred to as stove A) and an improved charcoal (here referred to as stove B) and compare
with the traditional three stone and the Kenyan metallic Jiko. The efficiency of the stoves were tested
using the water-boiling test (WBT), while particulate matter, CO and CO2 were monitored using data
loggers, which work on the principle of light scattering. Results were entered in the WBT data calculation
sheet to obtain the parameters critical in evaluating the stoves performance.
Results indicated a 50% and 72% decrease in CO emissions in Stove A compared to the three stone fire
wood stove and Kenyan metallic jiko respectively. A 60% and 34 % decrease in CO in charcoal stove B
compared to metallic charcoal jiko and three stone firewood stove respectively was noted. Both
traditional stoves fell below WHO limit of 30ppm over an hour of CO exposure.CO2 decreased by 20%
and 6% with stoves A and B respectively compared to three stone and metallic jiko. Charcoal Stove B and
Three-stone firewood stoves were above the 600ppm WHO limit. There was an 80% decrease in PM2.5 in
stove B, compared to metallic jiko and 17% decrease in stove A compared to three stone firewood stove.
All stoves except B exceeded 0.2mg/m3
limit set by WHO for PM2.5 when using biomass fuel. There was
a 63% and 185.7% increase in level of efficiency in charcoal stove B compared to the Metallic Jiko and
three stone stoves respectively. A 64% increase and 8% decrease in thermal efficiency in stove A
compared to three stone stove and Kenyan metallic jiko respectively were noted. A 73% and 23%
decrease in specific fuel consumption was noted in firewood stoves A and charcoal stove B compared to
the metallic and three stone firewood stove respectively. Objectives of the study were met.

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CHAPTER 1
1.0. INTRODUCTION
Indoor air pollution is the presence of physical, chemical and biological contaminants in air that
are not normally present in outdoor air of a high quality system (Ezzati M, 2000). Indoor air
pollution is a concern in the developed countries, where energy efficiency improvements
sometimes make houses relatively airtight, reducing ventilation and raising pollutant levels.
Indoor air problems can be subtle and do not always produce easily recognized impacts on
health. Different conditions are responsible for indoor air pollution in the rural areas and the
urban areas. In the developing countries, the rural areas face the greatest threat from indoor
pollution, where some 95% of the population continues to rely on biomass for cooking and
heating. Concentration of IAP in households that burn traditional fuels are alarming (Clough,
2012). The use of biomass as a source of fuel in a confined environment results to increased level
of exposure. Women and children are the groups most vulnerable as they spend more time
indoors and are exposed to the smoke (Ezzati M, 2000). In 2009, the World Bank designated
indoor air pollution in the developing countries as one of the four most critical global
environmental problems (WHO, 2010). According to the study, daily averages of IAP often
exceed the current limits set by W.H.O. Although many hundreds of separate chemical agents
have been identified in the smoke from biofuels, the four most serious pollutants are particulates,
carbon monoxide, polycyclic organic matter, and formaldehyde. Although there has been no
large-scale statistically represented survey on the levels of emissions on stoves, hundreds of
small-scale studies show that use of biomass, as a source of fuel is the biggest contributor to
indoor air pollution in the world (Ezzati M, 2000). The problem has prompted the introduction of
improved stoves in developing countries to shift the focus from the traditional three stone to

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metallic charcoal stoves. This helps in improving the stove efficiency and reducing the level of
emissions from such stoves.
1.1 COOK STOVES IN USE IN KENYA
Cook stoves are classified based on the nature of fuel used as well as the different
modifications that they have undergone. Based on the classification of fuel used, there are two
types of stoves: Wood-based fuels and Charcoal-based fuel. If the classification is based on the
modifications, there are two types of stoves: Improved stoves and traditional stoves as will be
seen below.
1.1.1. THREE STONE COOKSTOVES
The traditional method of cooking is on a three stone cooking stove. It is the cheapest to produce
and set-up. It requires only three stones of the same height on which a cooking pot can be
balanced over a fire.
Fig 1.1 Picture showing a three stone stove in use
Courtesy of Google images
The method however, has a number of problems:
 Smoke is vented into the home instead of outdoors thus causing health problems.
According to the World Health Organization, "Every year, indoor air pollution is

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responsible for the death of 1.6 million people- that is one death every 20 seconds (WHO,
2014)."
 There is a lot of fuel wastage, as heat is allowed to escape into the open air. This requires
more labor on the part of the user in gathering fuel and may result to increased
deforestation if wood fuel is used.
 It can only serve one cooking pot at a time
 The use of the open fire increases the risk of burns and scalds. Especially when the stove
is used indoors, cramped conditions make adults and particularly children susceptible to
falling or stepping into the fire and receiving burns. Additionally, accidental spills of
boiling water may result in scalding, and blowing on the fire to supply oxygen may
discharge burning embers and cause eye injuries.
1.1.2. TRADITIONAL METAL COOKSTOVES
The traditional metal jiko (figure 1.2 below) is a charcoal stove of Kenyan origin mostly used in
the rural areas. The stove has the following specifications:
 A. Stove Body-Metal Cylinder
 B. Metal or Wood insulated Handle
 C. Feet for Elevation and Stability
 D. Damper/Fuel Access Port Door
 E. Fuel Feed/Ash Removal
 F. Grate
 G. Pot Adjustment-Simmer Position

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Fig 1.2 showing the a Kenyan traditional metal Jiko
It is of Kenyan origin and most preferred among the rural folks when the type of fuel is charcoal.
It is cheap compared to other charcoal stoves. It however has some disadvantages compared to
other improved versions such as the Kenya Ceramic Jiko and Eco-zoom Charcoal stoves.
 Low thermal efficiency
 High emissions
 High burn rate
 High risk of burns and scalds due to conductive parts
1.1.3. IMPROVED COOKSTOVES
Cook stoves are term “improved” if they are more efficient than the traditional types of cook
stoves in terms of performance and emissions. They are a modification of the traditional stoves
to ensure that the user saves on energy (heat loss), minimize the chances of burns, and reduce
indoor air pollution. Improved stoves reduce indoor air pollution because of their ability to
ensure that the minimum biomass used as fuel undergoes complete combustion. Cook stoves
come in a variety of designs targeting various types of biomass and cooking techniques that take
into consideration cultural diversities.

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Improved stoves have been produced and commercialized to the largest extent in China and
India, where governments have promoted their use, and in Kenya, where a large commercial
market developed. Some of the improved stoves commonly used in Kenya, albeit at a small
scale, include the designs by Ecozoom Company, Aprovecho, and Envirofit among others
(Ezzati M, 2000). Since the need for cleaner burning cook stoves around the world is vast, most
of the efforts on improved stoves have been trying to maximize and optimize on the advantages
it has over the traditional stoves. Some of the advantages improved stoves have over traditional
stoves are as follows:
 The efficiency of the stoves is very high
 Uses less wood or charcoal to cook an entire meal or boil water
 The level of smoke output is very low
 Less time and money spent on gathering fuel
 Low risk of burns and scalds due to insulation
Some designs of improved cook stoves used in the world today have been illustrated below:

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Fig.1.3 showing samplesof improved cooking stovesused in Kenya today
1.2. PROBLEM STATEMENT
Cooking is central to our lives, yet the very act of cooking is a threat to our health and well-
being. Half of the global population relies on the use of solid biomass such as dung, wood, crop
waste or coal to meet their most basic energy needs. In most developing countries, these fuels
burn in open fires or rudimentary stoves that give off black smoke. Children often carried on
their mothers back during the cooking are most exposed. The indoor smoke inhaled leads to
pneumonia, the biggest killer of children under 5 years of age and other respiratory diseases
(Gordon, 2014). Indoor air pollution is responsible for nearly half of the more than 2 million
deaths each year that are caused by acute respiratory infections (Gordon, 2014). The smoke
from cook stoves is not only a health hazard but also an environmental concern, as some of the
Stove A
Stove B

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gases produced cause global warming. Deforestation is also a key problem for those who use
biomass as a source of fuel. The research here provides scientifically backed results on the extent
of indoor air pollution from various cooking stoves albeit at a small-scale. Proper advancement
of this research on a large scale will go a long way to assist stakeholders in the health, energy
and environmental industry in their planning on how best to tackle the problem of indoor air
pollution.
1.3. OBJECTIVES
The main objective of this study was to ascertain the extent of indoor air pollution from both
traditional cook stoves and improved cook stoves in Kenya. Carbon monoxide, Carbon dioxide
particulate matter, thermal efficiency and the specific fuel consumption were the parameters
under study in this research.
1.3.1. SPECIFIC OBJECTIVES
 To determine the levels of carbon monoxide emitted by traditional cook stoves (wood
and charcoal) and improved cook stoves A and B ( wood and charcoal)
 To determine the levels of particulate matter emitted by traditional cook stoves and
improved cook stoves
 To determine the levels of carbon dioxide emitted by traditional cook stoves and
improved cook stoves
 To compare the level of emissions from each cook stove
 To determine the thermal efficiency of the stoves by using the water boiling test
 To compare the thermal efficiency of the different stoves

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 To determine the specific fuel consumption of each stove and compare with those of
others
1.4. JUSTIFICATION
Clean air is considered a basic human right that should be enjoyed by everyone regardless of his
or her socio-economic status and the quality of air inhaled is an important determinant of health
and wellbeing. Most of the people spend 90% of their time indoors, in homes, offices, schools,
health care facilities or other buildings (Ezzati M, 2000). The lack of a proper control mechanism
of the quality of indoor air quality poses a serious health challenge today. The exposure to indoor
air pollutants considered in this review over a long period has serious health implications on the
world population. WHO reports that the number of deaths due to indoor air pollution stands at
4.3 million per year. Being the second leading cause of death in developing countries and the
first by the year 2030 (UNEP, 2012).
Fig 1.4 Map showing indoor air pollution deaths per million populations
Source: The Lancet Respiratory Medicine (Gordon, 2014)

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Indoor air smoke contains a range of health-damaging pollutants, such as particulate matter,
carbon monoxide, carbon dioxide and persistent organic compounds such as Benzo(a) pyrenes.
Most poorly ventilated dwellings contain such pollutants in levels that exceed those accepted by
the WHO. Women and young children, who spend most of their time near the domestic hearth,
are particularly vulnerable making it not only a health or environmental problem but also socio-
cultural problem. A 2012 Global Burden of Disease study found that household air pollution
killed 3.5 million people a year — making it the deadliest environmental problem (Gordon et al.
2014).
Evaluation of the quantities of indoor air pollutants from the traditional cook stoves and
improved stoves will lead to measures that can be put into place to reduce the extent of indoor air
pollution (IAP) by carbon monoxide, carbon dioxide and particulate matter (PM2.5) as considered
in this review. This will in turn help improve the quality of life of the people who use biomass as
the source of fuel.

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CHAPTER 2
2.0. LITERATURE REVIEW
2.1. PARAMETERS
2.1.1. CARBON MONOXIDE
Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is slightly less dense than
air. It is a toxic gas that is produced from the partial oxidation of carbon-containing compounds:
It forms when there is limited supply of oxygen to combust carbon to-carbon dioxide (CO2), such
as when operating a stove or an internal combustion engine in an enclosed space (WHO, 2010).
The following reaction takes place:
2C(s) + O2 → 2CO (g) -----------Eqn. 1
Some properties of carbon monoxide are indicated in table 1.1 below.
Molecular weight 28.01g/mole
Melting point -205.1oC
Boiling Point (760mmHg) -191.5oC
Relative air density 0.967g/cm3
Solubility in water 2.14/100ml at 25oC
Table 1.1: some properties of Carbon monoxide
Source (WHO, 2010)
The molecular weight of carbon monoxide is similar to that of air. It freely mixes with air in any
proportion and moves with air via bulk transport (WHO, 2010). It is combustible, may serve as a
fuel source and can form explosive mixtures with air. It reacts vigorously with oxygen,
acetylene, chlorine, fluorine and nitrous oxide. Carbon monoxide is not detectable by humans by

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sight, taste or smell. It is only slightly soluble in water, blood serum and plasma: in the human
body, it reacts with haemoglobin to form carboxyhaemoglobin (WHO, 2010).
Hb (aq) + 4 O2(g) → Hb(O2)4-------------Eqn. 2
Hb (aq) + CO (g) → HbCO (aq) ---------------Eqn. 3
Equation 2 shows the normal reaction between haemoglobin and oxygen as is expected while
equation 3 shows the situation that occurs when carbon monoxide reacts with haemoglobin to
form carboxyhaemoglobin, which limits oxygen supply in the blood stream.
Inhalation remains the only exogenous exposure route for carbon monoxide. Anthropogenic
emissions are responsible for about two thirds of the carbon monoxide in the atmosphere and
natural emissions account for the remaining one third (Bas, 2004). Small amounts are also
produced endogenously in the human body. Exposure to low levels of carbon monoxide can
occur outdoors near roads, as it is also produced by exhaust of petrol and diesel motor vehicles,
hence parking areas can be sources of carbon monoxide (Ronald, 1998).
The major cause of indoor air pollution is the combustion of low-grade solid fuel and other
biomass in a small stove or fireplace. The emissions become lethal to occupants unless the flue
gases are vented outdoors via a chimney throughout the combustion process (Bas, 2004). The
following are the symptoms of exposure to indoor air pollution by carbon monoxide:
 At low concentrations, fatigue in healthy people and chest pains in people with
cardiovascular diseases
 Impaired visions and coordination
 Headaches, dizziness, confusion and nausea
The allowed limits set by WHO on the level of Carbon monoxide are as follows:

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Recommended Levels(mg/m3) Recommended Exposure Time Condition
100 15minutes Exposures to this level should
not occur more than once per
day(light exercise)
30 1hr Exposure to this levels should
not occur more than once per
day(light exercise)
10 8hrs Light to moderate exercise
7 24hrs Awake and alert but not
exercising
Table 1.3 Time weighed averages for Carbon monoxide
Source: (WHO, 2010)
2.1.2. CARBON DIOXIDE
Carbon dioxide (CO2) is a colorless, odorless, non-flammable gas that is a product of cellular
respiration and burning fossil fuels. It has a molecular weight of 44.01g/mol (WHO, 2010).
Although it is typically present as a gas carbon dioxide can exist in solid form as dry ice and
liquefied, depending on the temperature and pressure. The gas is widely applied in various
industries such as the breweries, mining industries and industries manufacturing carbonated
drinks, disinfectant and baking powder. In addition, the gas is primarily associated with volcanic
eruptions.
CO2 is present in the atmosphere at 0.035%. Most of the indoor carbon dioxide forms when
carbon undergoes complete combustion (WHO, 2010).

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C(s) + O2 (g) →CO2---------------Eqn.4
Occupational Safety and Health Administration has set a permissible exposure limit for
Carbon dioxide as 5000ppm over an 8hr workday. This is equivalent to 0.5% by volume of air.
Similarly, the American Conference of governmental industrial hygienist puts a thresh-hold limit
of 5000 ppm for an 8-hour workday with a ceiling value of 30000 ppm for a 10-minute period
based on acute inhalation data (Bas, 2004). 40,000 ppm is considered immediately dangerous to
life. Additionally acute toxicity data show that the lethal concentration of CO2 in air is 90000
ppm over a 5-minute exposure. It is important to determine the levels of Carbon dioxide in a
building to know whether the room is safe for human occupancy. Although CO2 is considered
harmless in the right conditions, it is one of the deadliest gases when inhaled in confined areas
(WHO, 2010). At high concentrations, CO2 acts as an oxygen displacer leading to dizziness,
suffocation and even death. This occurs when there is a depression of the CNS due to high
concentrations of carbon dioxide and the body’s compensatory mechanisms fail (Gordon, 2014).
The main route of exposure of CO2 is through inhalation. Once CO2 enters the blood
stream it results to acidosis due to an excess of CO2 in the blood stream than in the lungs. This
results to a concentration gradient where CO2 diffuses into the lungs. The imbalance created
causes an imbalance in the body PH as the blood becomes more acidic than the normal
physiological process occurs leading to acute shortage of oxygen hence the asphyxiation if the
exposure to CO2 was much higher.
Apart from being a health hazard, Carbon dioxide is one of the most dangerous
greenhouse gases (UNEP, 2012). It is responsible for much of the global warming that takes
place in the world hence leading to much of the negative environmental impacts experienced in

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the world such as the melting of the polar ice caps, rising of the ocean levels which might
eventually lead more deaths than even the deadliest diseases combined if the trend continues.
2.1.3. PARTICULATE MATTER PM2.5
Particulate matter (PM) is an air pollution term referring to a mixture of solid particles and liquid
droplets suspended in the air. They consist of different sizes and different materials and
chemicals (WHO, 2010). The particles are small enough to be inhaled and with a great potential,
to cause serious health effects. The classification of particulate matter is dependent on the size of
the particles’ diameter. There are two main classes of PM: PM2.5 and PM10.The former involves
all particles suspended in the air with a diameter of 2.5µM and below while the latter deals with
particles, with a diameter of 10µm (Gordon, 2014). Of particular concern is a class of particles
known as fine particulate matter or PM2.5 that get deep into the lung (WHO, 2010).
There are various sources of PM. They could originate from natural process, like fire and
wind erosion, and from anthropogenic activities such as agricultural practices, smokestacks, car-
emission and indoor emission from cook stoves. The smoke from the cook stoves contain
particulate matter which contains a mixture of various substances such as VOCs (Volatile
organic matter) and other organic matter like Black carbon(soot) and Benzo(a)pyrene-classified
as class A carcinogen. In studies carried out by IARC, the level of lung cancers in women and
children in most developing countries could be attributed to the PM in indoor air pollution (Wild,
2008).
According to the World Health Organization, the level of PM2.5 permissible when using a
traditional stove with biomass fuel should not exceed 0.1mg/m3 on a 30-minute average
(WHO, 2010). Following a study by the European Commission on the toxicity of indoor air

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particulate matter, the level was standardized and set up us 25µg/m3 for a 24-hour exposure,
which was not to exceed 3 days per year (WHO, 2010).
Numerous scientific evidence points towards the link between PM pollution exposures to
a variety of health problems (WHO, 2014). They include:
 nonfatal heart attacks,
 irregular heartbeat,
 aggravated asthma,
 decreased lung function, and
 increased respiratory symptoms, such as irritation of the airways, coughing or difficulty
breathing.
 premature death in people with heart or lung disease
WHO points out that nearly 50% of pneumonia deaths among children under five are due
to particulate matter inhaled from indoor air pollution and both women and men exposed to
heavy indoor smoke are 2-3 times more likely to develop chronic obstructive pulmonary disease
(COPD) (WHO, 2009). People with heart or lung disorders, children and adults are the most
likely affected by particulate matter exposure. Healthy people may also experience temporary
symptoms from exposure to elevated levels of particle pollution.
2.1.4. THERMAL EFFICIENCY
In thermodynamics, the thermal efficiency ( ) is a dimensionless performance
measure of a device that uses thermal energy, such as an internal combustion engine, a steam
turbine or a steam engine, a boiler, ,cook stove, a furnace, or a refrigerator for example. The
efficiency indicates how well an energy conversion or transfer process is accomplished. It is

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determined by finding the ratio of heat output and input. Thermal efficiency is expressed as
percentage (Kalyan, 2001).
The above equation helps in comparing between two combustion systems such as
different types of cooking stoves to determine which one uses more fuel to complete a given
cooking task. This helps in coming up with ways to modify the system to improve the stove, for
example to use less heat energy to complete a given task. A stove with high thermal efficiency
uses less biomass or fuel and burns for a relatively long time.
2.1.5. SPECIFIC FUEL CONSUMPTION
Specific fuel consumption refers to the amount of fuel consumed to provide or produce a given
unit of output (Kalyan, 2001). It is expressed in g/litre in the case of water boiling test. In the
case of cooking stove study, it is the amount of fuel in grams consumed per liter of water boiled.
The specific fuel consumption can be used alongside other parameters to determine the
performance of a given stove. This is achieved by comparing with those obtained from other
cook stoves
2.1.6. THE WATER BOILING TEST
The water-boiling test is a stove performance that simulates the kitchen set-up to evaluate stove
performance while completing a standard task (boiling and simmering) in a controlled
environment. It aims at investigating the rate of heat transfer (thermal efficiency) of the stove as
well as determining the extent of indoor air pollution.
The test is preferred for the following reasons:
 It is easy to set up

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 It is a quick and cheap method of determining the technical performance of a cook stove
The water-boiling test is carried out in three phases, which follow each other successively. For
an entire WBT to be complete, one has to conduct at least three times (WBT Version 4.2.2) for
each stove. However, the latest version WBT 4.2.3 can accommodate results for up to ten tests.
The three phases of a WBT are as follows:
 Cold start High power phase
 Hot start High power phase
 Simmering phase
2.2.1 COLD START HIGH POWER PHASE
The tester begins with a stove at room temperature and uses a pre-weighed bundle of fuel to boil
a measured quantity of water in a standard (2.5 or 4 liters) Aluminium pot. The tester then
replaces the boiled water with a fresh water of ambient temperature and proceeds to the next
phase.
2.2.2 HOT START HIGH POWER PHASE
The test is conducted while the stove is still hot. Like the cold start, the tester uses a pre-weighed
bundle of fuel to boil the quantity of water in the same standard pot. The importance of the hot
start is to determine the stove performance between the stove when it is hot and when cold. It is
also an important aspect for stoves with high thermal mass (property of stove or any other
material to store heat thus providing inertia against temperature fluctuations. Stoves of this
nature absorb heat and thus re-radiate it as the temperature drops.

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2.2.3 SIMMERING PHASE
It is the third and final phase of the WBT test. It provides the tester with the chance to
determine the amount of fuel required to simmer a measured amount of water at just below the
boiling point for 45 minutes. The process simulates the cooking process of legumes and pulses,
which are common throughout the world.
2.3. ILLNESSES CAUSED BY IAP
2.3.1. CHRONIC OBSTRUCTIVE PULMONARY DISEASE
Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by chronic
obstruction of lung airflow that interferes with normal breathing and is not fully reversible. The
more familiar terms 'chronic bronchitis' and 'emphysema' are no longer used, but are now
included within the COPD diagnosis (WHO, 2010). COPD is not simply a "smoker's cough" but
an under-diagnosed, life-threatening lung disease. WHO estimates that 22% of COPD is
attributed to indoor smoke from solid biomass-fuel (Ronald, 1998).
2.3.2. LUNG CANCER
Lung cancer, also known as carcinoma of the lung or pulmonary carcinoma, is a malignant lung
tumor characterized by uncontrolled cell growth in tissues of the lung (Wild, 2008). Tobacco is
the major cause of lung cancer, however a small but significant number of cases in women have
been attributed to indoor air pollution related to burning of solid biomass. The risk affects 2.4
billion people globally with IAP accounting for 1.5% of lung cancer deaths (Gordon, 2014)
2.3.3. PNEUMONIA
Pneumonia is an inflammatory condition of the lung affecting primarily the microscopic air sacs
known as alveoli. Infection with viruses or bacteria and less commonly other microorganisms,

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certain drugs and other conditions such as autoimmune diseases usually cause it. Pneumonia
could also result from persistence of other respiratory diseases such as COPD, which are
associated with IAP. Other Health hazards associated with IAP include Cataracts, Asthma, low
weight and infant mortality rates in children (Gordon, 2014).

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CHAPTER 3
3.0. METHODOLOGY
3.1. APPARATUS AND REAGENTS
 EL-USB Carbon monoxide Data Logger
 UCB-PATS Data Logger from Berkeley Air Monitoring group(PM2.5)
 HI 9043 K-Type Thermocouple Thermometer
 Electro physics wood moisture meter
 Electronic Kitchen scale model EK 3752 (Max 5kg or 11 lbs.)
 Digital timer
 Laptop
 Digital Camera
 Heat Resistant gloves
 80 liters of clean water
 Bio Ethanol Gel
 Aluminium pots of standard size
 Charcoal
 Firewood
 Dust pan for transferring charcoal
 Shovel for removing charcoal from stove
3.2. TEST PROCEDURE
3.3. PRELIMINARY STEPS
Before the actual test was conducted, the following steps were carried out

28. 28
 Tap water was collected and filled in four-20 litres containers for use during the
entire experimental process
 Sufficient wood (15Kg) and charcoal (10Kg) was collected and stored for use
during the entire process
 A 4 litre capacity aluminium pot was chosen as the pot to use for the WBT test
 The site for carrying out the experiment was chosen and the conditions controlled
by limiting the ventilation of the area (attained by closing all the windows but
letting little space to vent out some harmful emissions from the cook stoves.
 The types of stoves to be tested were carefully chosen as follows: The traditional
three stone stove, the traditional metal jiko, Stove A (an improved wood stove)
and Stove B (Improved charcoal stove)
3.4. TESTING PROCEDURE
The first page of the WBT form was filled with information about:
 Name of the tester
 The type of stove A (improved Wood) and Stove B (Improved charcoal stove)
 Location of the test
 Testing conditions
The two data loggers (the UCB-particulate meter and the CO-CO2 meter) were configured using
the PSI software installed on a laptop/computer. The configuration involved also setting the time
intervals for which the data loggers were to keep running.
The following parameters were then measured and recorded in the WBT forms:
 Air temperature

29. 29
 Wood dimensions (length x width x height), the pieces of wood that were selected were
of similar and optimal size for the cook stoves
 Weight of bundle of wood per step
 Wood moisture (% for the wet basis) using the Electro physics wood moisture meter
 Dry weight of the Aluminium pot
 Weight of charcoal
 Local boiling point of water using the thermocouple thermometer
Having filled the parameters on the WBT data calculation form, the following tests proceeded
for each of the stoves.
3.4.1. COLD START HIGH POWER PHASE
1. The timer was set and fire lit. 4 liters of water was added to the standard Aluminium pot
and the weight of the two measured using the Electronic Kitchen scale model EK 3752
(Max 5kg or 11 lbs.) and recorded in the WBT Version 4.2.2
2. Using a thermocouple thermometer, the temperature of water was also measured at room
temperature and recorded as the initial temperature
3. The fire was started at room temperature in a reproducible way as is done locally in the
kitchen. Once the fire started, the starting time was recorded. During the boiling process,
the fire was controlled to ensure that the water boiled with minimal wastage of fuel.
4. When the water in the pot reached the pre-determined boiling point of 94 OC, the boiling
time (stopping time) was recorded
5. All the wood/charcoal from the stove that remained after boiling was removed and flames
extinguished. For the wood fuel, the loose charcoal was knocked from the ends of the
wood into the pan for weighing. and the mass recorded

30. 30
6. The pot containing the boiled water was weighed and the mass recorded in the WBT
form.
This completed the cold high power phase and the next phase began immediately while the stove
was still hot.
3.4.2. HOT START HIGH POWER PHASE
1. A similar amount of water (4 Liters) was added to the same Aluminum pot and the mass
of the two taken and recorded in the WBT data calculation form. The initial temperature
was also measured and recorded in the same form
2. The fire was lit using kindling and wood from the second pre-weighed bundle designated
for this phase of the test. The same was done for the charcoal stove however fanning
instead of kindling was done to prevent time wastage that might have interfered with the
results. Starting time was recorded and the fire controlled as in the previous phase. Time
at which the pot reaches local boiling point was recorded
Having attained the local boiling point and recording the value in the WBT form, the following
was conducted:
 Unburned wood or charcoal from the stove was immediately removed and any loose
charcoal knocked off from the wood carefully in a way that does not interfere with the
combustion area.
 The fuel remaining was weighed and recorded in the WBT form. The same fuel
remaining in this phase was to be retained for use in the final simmering phase. The

31. 31
weight of the boiled water in the pot was taken and the pot placed in the stove
immediately for the final phase immediately.
3.4.3. SIMMERING LOW POWER PHASE
 The starting time was recorded in the WBT data calculation form and the water simmered
for 45 minutes. During the process, the fire was adjusted to ensure that the temperature of
the water remained within the simmering range of 4oC below the boiling point (A test is
considered invalid if the temperature of the water undergoing simmering drops by more
than 6oC below the local boiling temperature.
 After the 45 minutes, the temperature of the water was recorded and the finish time
recorded. The fuel from the stove was removed, weighed and the value recorded in the
WBT form.
In accordance with the WBT Version 4.2.2 guidelines on stove performance, the above
procedures were conducted thrice for each complete test. Having completed the test for each
stove, the Water Boiling Test results obtained were entered into the Data Calculation Software to
obtain the required outputs. The CO, CO2 and particulate matter emissions data were also
downloaded from the respective data loggers and the results entered into the WBT calculation
sheet for analysis.

32. 32
Fig 1.5 the general set up of IAP in WBT
The following are the instruments used during the experimental part of the project
INSTRUMENTATIONS
Fig 1.6 and 1.7 the EL-USB CO Data Logger and the Tel-Air Carbon monoxide monitor
Fig 1.8 UCB-PATS from the Berkley Air-monitoring group
Thermometer
Air monitorsWindows kept closed
100cm
145cm
Weighing scale

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CHAPTER 4
4.0. RESULTS AND DISCUSSION
Stove performance parameters are based on an analysis of results obtained from the
Water Boiling test experiment. The information required for analysis, includes the time taken to
boil a given volume of water, the burning rate, thermal efficiency, specific fuel consumption and
a measure of indoor air pollutants from the stoves. Table 1.4 below shows the results of the stove
performance parameters from the experiment conducted.
Table 1.4 the average result obtained for the three phases of the entire experiment
Units Traditional
Metal Stove
Three stone
Cooking
stove
Stove A Improved
Wood stove
Stove B Improved
Wood Stove
Time to boil Min 31 ± 0.5 20 ± 2.0 19±0.0 28±3.5
Burning rate g/min 8 ± 2.0 38 ± 2.1 15±1.0 5±0.0
Thermal
efficiency
% 25 ±1.0 14 ± 1.5 23±1.5 40±0.5
Specific fuel
consumption g/liter
63 ± 0.5 302± 18.5 82±3.0 46±7.0
Fuel
Consumption
G 240 ± 19.5 875.5±76.5 403±14.0 173±24.0

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CO2 Ppm 583±88.0 646±65.6 518±57.0 619±33.3
CO Ppm 76±0.5 46±0.0 23±0.5 30±4.5
Particulate µg/m3 334±17.0 636±6.5 531±100.5 65±11.4
Carbon dioxide
The results for carbon dioxide emissions from the cook stoves are as follows:
Figure 1.9 showing CO2 emissions from the four stoves
It is evident from figure 1.9 that the three stone recorded the highest level of carbon
dioxide emissions while stove A had the least. There was a 20% decrease in the level of CO2
emissions in stove A compared to three stone stove. A 6% increase in level of carbon dioxide
emissions from stove B compared to the Kenyan metallic jiko was noted from the study. Stove B
and the three stone cooking stoves had exceeded the WHO limits set for Carbon dioxide
emissions, which stands at 600ppm over an hour of exposure. The high level of carbon dioxide
0
100
200
300
400
500
600
700
800
Three stone Stove A Wood Traditional Metal
Stove
Stove B Charcoal WHO guidelines
1hr
Carbon iv Oxide (ppm)

35. 35
emitted in stove B is a deviation from what is expected to occur. It is expected that level of
carbon dioxide emitted in charcoal stoves should be lower than the wood fuel stoves due to
complete combustion that take place in wood stoves. The most probable reason for the deviation
of carbon dioxide emission is that the stove is slightly elevated, as a result of the modifications it
underwent to improve its efficiency. The distance between the door and the fuel containment
area is relatively large and therefore there may be increased air intake thus high combustion rate
leading to more carbon dioxide produced.
.
Carbon monoxide
The graph below (figure 2.0) shows the results of carbon monoxide emissions obtained for the
four cook stoves.
Figure 2.0 CO emission from the four stoves
It is evident from figure 2.0 that wood stoves emit less carbon monoxide compared to the
charcoal stoves. This is attributed to the increased extent of combustion taking place in the wood
stoves than in charcoal stove where the air is limited. Improved stoves both (A) wood and (B)
0
10
20
30
40
50
60
70
80
90
Three stone Stove A Wood Traditional Metal
Stove
Stove B Charcoal WHO-I hour
exposure limits
Carbon monoxide (ppm)

36. 36
charcoal resulted to less carbon monoxide emissions compared to the traditional. There was a
50% decrease in level of CO emitted in improved stove. A (wood) compared to the three stone.
The level of Carbon monoxide emission in Stove B was 60% and 34% less compared to the
Kenyan metallic jiko and three stone stoves respectively. All the traditional stoves fell below the
WHO limit 30 ppm for carbon monoxide emission. Stove A (wood) fell below the WHO
guidelines while stove B had CO emitted equal to the limit set by W.H.O.
Particulate Matter PM2.5
The graph below (figure 2.1) shows the average emissions of particulate matter PM2.5 from the
cook stoves tested.
Figure 2.1 Particulate Matter emissions from the four stoves
Figure 2.1 shows that charcoal stoves emit less particulates compared to the wood stoves. This is
attributed to the nature of the fuels used. Wood fuel is not completely carbonized and hence
contains other substances, which are emitted when burnt hence producing high amount of
particulates. In the test, there was an 80% decrease in level of particulates in stove B compared
0
100
200
300
400
500
600
700
Three stone Stove A Wood Traditional Metal
Stove
Stove B Charcoal WHO
limits(Biomass
fuelstoves)
Particulate matter(µg/m3)

37. 37
to the traditional Kenyan metallic stove while a 17% decrease in emissions in stove A compared
to three stone stove. All the stoves except stove B exceeded the accepted levels of PM2.5
emissions for stove using biomass fuel. The level set up is 0.1mg/m3 over a 30-minute exposure
(translating to 0.2mg/m3 over an hour exposure).
Thermal Efficiency
The graph below (figure 2.2) shows the results for the thermal efficiency of the cook stoves
tested. It is expressed as a percentage.
Figure 2.2 thermal efficiency of the four stoves
It is evident from figure 2.2 that charcoal stoves have high thermal efficiency compared
to the wood stoves. This is most probably because charcoal is fully carbonized hence undergoes
rapid combustion unlike wood where there fuel is not fully carbonized. The high thermal
efficiency in charcoal stove could also be attributed to the high calorific value of charcoal
(29000KJ) compared to wood (13600KJ) (Kalyan, 2001). is It is also evident that improved
stoves have higher improved thermal efficiency compared to the traditional stoves due to the less
heat loss to the surrounding. The insulation material used in the improved stoves A and B is the
0%
20%
40%
60%
80%
100%
Three stone Stove A Wood Traditional Metal
Stove
Stoved B Charcoal
Thermal efficiency %

38. 38
ceramic fiber. There is a 63% and 185.7 % increase in level of efficiency in stove B compared to
the Kenyan Metallic Jiko and three stone stoves respectively. A 64% increase and 8% decrease
in thermal efficiency in stove A compared to three stone stove and Kenyan Metallic jiko was
noted.
SPECIFIC FUEL CONSUMPTION
The graph below (figure 2.3) shows the results for the specific fuel consumption obtained for
each stove for the entire testing period.
Figure 2.3 specific fuel consumption of the four stoves
It is evident from figure 2.3 that wood stoves have a higher specific fuel consumption compared
to the charcoal stoves. The presence of sufficient air in the wood stoves ensures that combustion
takes place at a faster rate in the wood stoves as compared to the charcoal stoves. The effect is to
use a large amount of fuel per a given volume of water boiled. The three stone recorded the
0
50
100
150
200
250
300
350
Three stone Stove A Wood Traditional
Metal Stove
Stove B
Charcoal
Specific fuel consumption(g/litre)
Specific fuel consumption(g/litre)

39. 39
highest specific consumption while Stove B recorded the lowest. There was a 27% decrease in
specific fuel consumption in Stove B compared to Kenyan metallic jiko. It is also evident that
there was a 73% decrease in specific fuel consumption for stove A. compared to three stone
stove.

40. 40
CHAPTER 5
5.0. CONCLUSION, RECOMMENDATIONS AND RELEVANCE OF FINDINGS
5.1. CONCLUSION
Based on the results obtained, the main objectives and specific objectives of the research were
achieved. The study showed that the levels of emissions from the traditional stoves (three stone
and the traditional Kenyan metallic Jiko) are above the accepted standards set by W.H.O. The
efficiency and the specific fuel consumption of the traditional stoves are also not economic as
compared to the improved cook stoves, which have less emission (below the WHO limits). It
was evident that the levels of emissions from the traditional biomass cook stoves (three stone and
the traditional Kenyan metallic jiko) are above the accepted standards set by the World Health
Organization. It is also evident from the study results, that efforts to further improve the
improved stoves may lead to an improvement in efficiency but compromise on the other
parameters such as emissions.
5.2. RECOMMENDATIONS
 Since the WBT is carried out in an environment where conditions are controlled and
carried out by qualified technicians, the method has some slight weakness, as it does not
fully give a picture of what happens in real household cooking. Further research on the
same should be extended to real household level by incorporating other tests such as the
Kitchen performance test and the Controlled-cooking test.
 The people need to be sensitized on the harmful effects of indoor air pollution. They
should be advised to try outdoor air cooking which dilutes the emissions from the
biomass-fuel stoves.

41. 41
 The government and other stakeholders in the energy sector should come up with
guidelines on how to set up standards for all stoves manufactured locally or abroad to
ensure that they emit low emissions and exhibit high efficiency.
 Despite high levels of poverty condemning people to use biomass fuel, there should be a
plan by the government on how to shift towards greener and cleaner energy sources such
as Liquid petroleum gas, geothermal and solar energy.
5.3. RELEVANCE OF FINDINGS
The findings are important as they show that improved stoves improve on efficiency and
reduce the specific fuel consumption as well as cutting down on emissions. They also help to
reduce the level of indoor air pollution by a significant level. This goes along with the economic
pillar Kenya’s vision 2030 of working towards sustainable energy sources. It also helps Kenya in
its quest to join the list of industrialized countries, work towards the attainment of the
Millennium development goals (MDGs). The reduction in Indoor air pollution serves well to
attainment of most MDGs:
MDG 4: By reducing IAP, the will be a reduction in of infant and child mortality rate.
MDG3: Promote gender equity and women empowerment. Since most of the cooking and
collecting of biomass fuel is done by women and girls, improved stoves will save on the fuel
consumption needs of the family and this saves time since the time they would be fetching
biomass fuel could be used for empowerment activities such as education or other economic
activities.
MDG5: Improvement in maternal health. The attainment of goal 3 and goal 4 leads to the
attainment of goal no.5

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MDG7: Ensure environmental sustainability. The use of improved stoves leads to a reduction in
indoor air pollution hence cutting down on the level of greenhouse gases.
The findings from the results also affirm that improved stoves are the way to a sustainable future
in terms of energy saving needs. This helps the “Jua kali” sector in Kenya to continue making
more improved stoves hence improving their economic statuses, which go along well with
growth of the Kenyan economy as they pay tax from the sale of the stoves.

43. 43
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Kalyan, I. K. (2001). Advanced Thermodynamics Engineering. CRC Press.
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