Cooking with firewood, dung and crop residues is associated with significantly higher health risks due to indoor air pollution. When respondents were asked to give an approximation on the levels of smoke produced when using biogas in comparison with wood fuel, 99% of the respondents reported that the amount of smoke produced when using firewood and charcoal was much more compared to biogas, and only 1% reported that smoke levels were the same irrespective of the fuel type in use. When asked if they experienced dizziness or (and) headache when cooking with firewood and charcoal, 70.4 % responded in the affirmative while 27 reported that they did not experience the symptoms. When the same question was posed on their experience with biogas stoves, majority (95%) of the respondents reported that they did not experience dizziness or headache when using biogas and only a few of the respondents (4%) reported in the affirmative
A further investigation on the incidences of coughing and itchy eyes among users when cooking with the traditional fires compared to biogas stove, revealed that 70% of the respondents experienced cases of coughing and itchy eyes while using firewood and charcoal. When asked their experience with biogas cookers, only 8 % said they
experienced coughing, while an overwhelming majority of respondents (92 %) did not cough or rub their eyes when using the new devices (biogas cookers). Figure 10 shows health effects among household members disaggregated by gender, before and after biogas installation. Case No. 2 brings out the health impacts to households, in addition to the other benefits.
Figure 10: Health effects before and after installation and use of biogas
It is worth noting that physical burns, itchy eyes and respiratory problems were the most cases by gender and age bracket of the family members. Female adults (25 years and above) and female children were the most affected. For example, during pre-installation phase where the household would depend on firewood and charcoal for cooking, 53.4 %
0 10 20 30 40 50 60 70 80 90 100 Coughing & respiratory problems Itchy eye Burns Dysentery/ diarrhoea Bad odour/ smell
female adults and 27 % female children reported coughing and other respiratory ailments while only 6.2 % male adults and 7.5 % male children had similar problems. The number of cases reported dropped significantly with the use of biogas, where only less than 3% female and male adults reported experiencing respiratory problems. This reduction is mainly attributed to biogas fire, which is clean and produces no smoke, is pollution free and with no particulate matter and therefore likely to cause minimal or none at all health harm to users (Carolyn et al., 2012).
The high number of females both adults and children affected by smoke compared to their male counterparts could be explained by the fact that in most African cultures, women are the ones who are involved in food preparation for the household, and therefore spend most of their time in kitchens (which are often poorly ventilated), and hence become more exposed to products of incomplete combustion (Kammen et al., 2007). There we no girls who had respiratory related problems on post-installation, and this could perhaps be attributed to the fact that girls could go to school since their need for collecting firewood and helping mothers with household chores had been reduced significantly.
Other health issues identified included burns, bad odour and dysentery. These too were reported to be widespread pre-installation phase of the biogas, but reduced tremendously with biogas use. For example about 51.7 % females reported that they had burns pre-installation period compared to only 4 % post installation. This drop in burns could be attributed to a reduction in firewood use and hence less burns resulting from physical pushing of the burning pieces of wood.
The findings of this study agree with the findings by Harikatuwal and Bohara (2009), on impacts of biogas on rural households in Nepal. They reported that disease incidences dropped drastically post biogas installation, with females reporting the most decline. For example; among females, there was 39.7% reduction in eye infections, 40.9% in headaches and 26% in cough and respiratory ailments. Similarly, men in the same population reported 19.7% reduction in eye infections, 20.2% in headaches followed by 15.3% in cough and respiratory problems.
In the current study, the observed decline in health related problems with biogas use, was attributed to reduction in user exposure to products of incomplete combustion (PIC) such as CO, nitrogen dioxide (NO2), polyaromatic hydrocarbons (PAHs) and elemental carbon aggregates (soot), resulting from residential wood combustion. Use of firewood and charcoal produces obnoxious smoke and particulates (Bruce et al., 2000), which could have posed direct health risks and respiratory diseases such as acute lower respiratory infection, reported as coughing. Exposure to ambient particulate matter has been associated with a range of negative health effects including increased morbidity and mortality from pulmonary and cardiovascular diseases (Ostro et al., 2006). Borm and Donaldson, (2007), and Barregard et al., (2008) in their studies associate particulate matter from wood combustion with a range of pulmonary effects such as decreased lung development and function, exacerbation of asthma, chronic obstructive pulmonary disease (COPD) and increased incidences of lung cancer. Several mechanisms including particle induced oxidative stress, inflammation, cyto-toxicity and genotoxicity have been used to explain the association between particle exposure and adverse health effects. Burning wood of poor quality (e.g. with high moisture content), overloading the
fireplace and insufficient air supplies are examples of conditions that can lead to incomplete combustion.
According to Integrated Environmental Impact Analysis carried out by Biogas Support Programme in Nepal on 600 biogas users and 600 non-users, 4% more non-biogas users had respiratory diseases compared to those that were using biogas energy (BSP, 2000). Quantitative information from various household surveys revealed that problems like respiratory illnesses, eye infection and lung problems decreased after installation of biogas plants (BSP, 2000). Mwakaje (2008) observes that by substantially reducing indoor smoke and drudgery for women biogas digesters contributes to improved health and reduction in medical expenditure. This observation is also reported by Srinivasan (2008).