Abstract:
Firewood is a dominant household fuel type used in many developing countries. Even in
countries where there is improved access to electricity, most households still rely on firewood
for their energy needs. Harvesting of some wood is illegal, however the high poverty rate,
absence of alternative fuels and lack of law enforcement means even the protected wood
species will continue to be used, with consequent pressure on the forests. Furthermore, the
combustion of firewood for domestic use takes place in poorly ventilated homes emitting
hazardous pollutants, which causes indoor air pollution and affect human health.
The use of firewood as a household fuel can be superimposed nearly perfectly on that of socioeconomic development. Additionally, the use of household firewood is invariably associated
with poverty in countries, in communities within a country and in households within a
community. Indoor air pollution studies on human health should then consider socio-economic
factors which seem to be one of the determinants of both firewood use and ill health, a
determinant which is often neglected in most indoor air pollution studies. Domestic inhalation
of firewood smoke is one of the mechanisms linking socio-economic (poverty) to disease.
The current study sought to determine a baseline of wood usage and health risks caused by
volatile organic compounds in Senwabarwana villages. This study integrated observations,
ethnobotanical meta-analysis and experimental into one comprehensive integrated
environmental health risk assessment framework to assess the risks associated with exposure
to volatile organic compounds from firewood combustion. Basic information about firewood
usage, socio-economic dynamics and perceived health problems related to volatile organic
compounds was collected using a structured questionnaire. The Vac-U-Chamber was used to
sample the air.
The results show that firewood is extensively used in poorly ventilated kitchens for cooking
and home heating in Senwabarwana villages. Ten priority firewood plant species are frequently
used in the study area, namely Mohweleri (Combretum apiculatum), Moretshe (Dichrostachys
cinera), Motswiri (Combretum imberbe), Mokgwa (Acacia burkei), Mushu (Acacia tortilis),
Motshe (Cussonia paniculate), Mokata (Combretum hereroense), Mphata (Lonchocarpus
capassa), Mokgalo (Ziziphus mucronate) and Mogwana (Grewia monticola), in their order of
preference. The results also indicated thirteen common reasons or factors that influence the hoice of firewood plant species by households, the main four being: (i) the embers formed
during combustion, (ii) heat value, (iii) low ash content and (iv) availability of the firewood
plant species. Further analysis revealed several uses and ranking thereof, including reviewing
the national status and legal profile of each identified plant species. The study found that most
of the firewood species used in Senwabarwana Village were indigenous. Major drivers of
firewood use are household income, educational status of breadwinners, family sizes, and place
of residence, fuel affordability and accessibility, among others.
Concentrations of benzene, toluene, ethylbenzene and xylene per plant species were studied to
assess the risk exposed to the Senwabarwana community. Literature indicates that these
pollutants have several health effects associated with acute exposure such as eye, nose and
throat irritation, headaches, dizziness, nausea and vomiting. Both hazard quotient and hazard
index were found to be less than one indicating no risk exists with the use of plant species used
for firewood in Senwabarwana even to sensitive individuals. The risk of developing health
effects due to the presence of the studied volatile organic compounds can be assessed as
negligible.
Since firewood is a more convenient source of energy, it is recommended that the size of the
windows be extended for ventilation. Agroforesty should also be implemented as a
conservation method. The wood that emits less concentration of pollutants be used for
firemaking.
