Biomass Fuel Smoke and Health Effects in Nepal

Introduction Health hazards of housewives have been traditionally underestimated in the developing countries. It is considered as a social responsibility of the women. The work of housewives can be categorised as hazardous occupation as they might be exposed to volatile organic compounds (VOC) and polycyclic aromatic hydrocarbons (PAH) everyday. There are evidences that indoor air pollution may increase the risk of respiratory tract infections and lung cancer among housewives. About 50 % of the world''s population is estimated to use solid biomass fuels like animal dung, crop residues, wood and coal for cooking daily meals and heating homes. Exposure from bio-mass smoke is estimated to cause a annual global death toll of 2.5 million equivalent to 4 to 5 % of total global deaths. In Nepal, epidemiological studies as such is lacking at the moment. However, census 2001 report shows that 80 % of households depend upon solid bio-fuels for domestic uses. The total deaths from asthma / bronchitis are reported to be 6.71% of total death. Objectives The objectives of this study were to find the health effects due to biomass fuel smoke and to describe exposure assessment of housewives and children below 5 yrs old who are exposed to bio-mass smoke during cooking time. Methods The study was done in five districts of Nepal namely, Kathmandu, Lalitpur, Bhaktapur, Chitwan and Nawalparasi. Ninety eight households were randomly selected from those districts and 168 housewives and 25 children l

Executive Summary

Background

Indoor air pollution in developing world from bio-mass smoke is considered to be a significant source of public health hazard, particularly to the poor and vulnerable women and children. About 50 % of the world''s population is estimated to use solid bio-fuels like animal dung, crop residues, wood and coal for cooking daily meals and heating homes and exposure from bio-mass smoke is estimated to cause a global death toll of 2.5 million every year equivalent to 4 to 5 % of total global deaths. In fact, the emerging data from recent studies indicate that risk-wise, it ranks only below malnutrition and poor quality of water/sanitation.

In Nepal, epidemiological studies as such is lacking at the moment. However, census 2001 report shows that 80 % of households depend upon solid bio-fuels for domestic uses. The total death from pneumonia alone is reported to be 4429 during the last 12 months preceding 2001 census (4.14 % of the total deaths). Similarly, the total deaths from asthma / bronchitis are reported to be 7170 (6.71%). According to Nepal Demography and Health survey, 2001, the prevalence of ARI for children below 5 years old is found to be 23 %. The below 5 years population is 12.1 % of the total population.

Study Components / Activities

This study is basically a field-oriented epidemiological study program linked with direct measurement and observational works, and is meant to provide the required baseline data to the policy / decision makers on the state of kitchen smoke pollution and the possible serious health outcomes to the exposed population, which could be substantial in terms of DALYs (Disability Adjusted Life Years) and other losses, and that there is a range of intervention methods available that could be implemented selectively and cost-effectively with local participatory approach.

The main components of the study are:

1. Baseline data survey on household characteristics, domestic energy uses, kitchen ventilation, types of stoves used for cooking, user behaviors etc.

2. Indoor air pollution (smoke/PM10, CO, other gaseous emissions) monitoring particularly during cooking hours at kitchens using solid bio-fuels (dung, crop residues, wood) or cleaner fuels (SKO, LPG, Bio-Gas).

3. Exposure assessment of respondents (women and children below 5 yrs old) who are exposed to bio-mass smoke during cooking time and calculation of daily integrated exposure indices.

4. Health response assessment which includes medical examination of respondents; data acquisition on health effects through questionnaires / interviews; computation of Comparative Risk Assessment (CRA), disease prevalence etc.

5. Recommended measures to reduce bio-mass smoke / exposure through appropriate interventions, ventilation improvements, awareness raising etc.

Activities carried out included the following:

? Area and Household Coverage / Respondent Size: The hill area is limited to Kathmandu valley districts and terai area is limited to Chitwan and Nawalparasi districts. The surveyed and studied household size is altogether 98, 58 from hills and 40 from terai inclusive of both rural and urban areas.

? The respondent size, mainly women who cook, is 168 in number, who went through medical examination and questionnaire interviews.

? Smoke / PM10 as well as CO were measured in each kitchen during cooking time. Other gaseous emissions (SO2, NO2, HCHO) were measured in kitchens during cooking time on campaign basis only. Measurements of PM10, gaseous concentrations were carried out in indoor and outdoor ambient air as and when necessary.

? On the basis of data / information obtained from above, indoor and outdoor air pollutions were estimated; smoke / PM10 exposures experienced by the respondents under various environmental settings were calculated; and the health outcomes assessed using various statistical tools. The basis for comparative risk assessment with respect to various diseases / symptoms is the binary fuel uses in the studied kitchens, namely, solid bio-fuel users and the users of cleaner fuels like gas and kerosene.
Key Findings

Smoke / PM10 Pollution

? The smoke pollution is found to be the highest in kitchens having traditional clay stoves and using solid bio-fuels (dung, crop residue and wood) while cooking where the mean PM10 concentration level is found to be 2418 ?g/m3 (average of 62 readings).

? Under similar ventilation and other household conditions, the mean smoke / PM10 concentration level in kitchens using cleaner fuels (kerosene, LPG, biogas) is found to be 792 ?g/m3 (26 readings) which is about 3 times low.

? Under above conditions, the daily integrated PM10 exposure index level is estimated to be 15.58 mg-hr/m3 for those exposed to solid bio-fuel smoke and 10.15 mg-hr/m3 for those exposed to cleaner fuels.

? While comparing smoke / PM10 pollution by eco-regions for solid bio-fuel users, the hill kitchens seem to be more polluted (Mean PM10, 2545 ?g/m3) as compared to kitchens from plains (Mean PM10, 2186 ?g/m3). Similarly, area-wise also, rural kitchens are more polluted (Mean PM10, 2427 ?g/m3) compared to urban kitchens (2124 ?g/m3). The observed differences in kitchen pollution can be attributed to differences in ventilation conditions. But for those using cleaner fuels, the pollution levels do not seem to vary much region-wise or area-wise.

? As has been observed in other countries, solid bio-fuels are the main sources of indoor air pollution for both hills and plains and also rural and urban homes of Nepal.

Health Responses

? The health responses recorded for all the respondents (168) exposed to various levels of air pollution in indoor kitchen during cooking time seem to corroborate fully with the state of exposure conditions to which each group of individuals is subjected. This means that those who are exposed to solid bio-fuels smoke show higher prevalence of respiratory abnormalities as compared to clean fuel users. For instance, prevalence of COPD and LRI among unprocessed fuel users was found to be 16.8% compared to only 7% for those using processed fuels (table 31).

? Similarly, much higher prevalence in all respiratory symptoms (2.5 to 4 times) has been found for unprocessed fuel users. For instance, 24.8% of the respondents using unprocessed fuels reported having breathlessness and wheezing and 14.4% reported having all respiratory symptoms. The corresponding figures for processed fuels were 7% and 4.7% respectively.

? Relative risk estimates in terms of Odds Ratios have also been computed in order to compare health outcomes (respiratory diseases and symptoms) associated with unprocessed fuel users as compared to processed fuel users. Statistically significant Odds Ratio (3.85) with 95% confidence interval, 1.11 ? 13.84 was detected for Chronic respiratory Diseases (COPD and Asthma jointly).

? Similarly, statistically significant Odds Ratios with 95% confidence level were found for respiratory symptoms, namely Cough (3.71), Phlegm (3.08), Breathlessness (3.71) and Wheezing (5.39). The 95% confidence intervals were 1.46 ? 9.46, 1.02 ? 9.32, 1.36 ? 10.13, and 1.57 ? 18.55 respectively.

? Considering smoking as a potential confounder, Odds ratios have been computed separately for Non-smokers and Smokers. The values show that Non-smokers have relatively higher odds ratio than smokers (5.21 for non-smokers and 1.52 for smokers) regarding COPD/Asthma taken jointly. Similarly, higher odds ratios were computed for non-smokers regarding all respiratory symptoms when compared to smokers.

? Similarly, considering age as another confounder, Odds ratios have been computed separately for two different age groups. The values show that for individuals aged below 40, the odds ratio is higher as compared to those aged 40 or above ( 3.04 for aged below 40 and 2.19 for aged 40 or above) regarding COPD/Asthma jointly. However, mixed results were obtained regarding different respiratory symptoms.

Conclusion

Indoor Air Pollution in Nepalese houses is real. The principal pollutant, smoke particulate originates from freshly combusted biomass. The ensuing smoke exposure conditions are unacceptable by any human standards and therefore, severe health effect attributable to indoor kitchen air seems indisputable.

A wide range of interventions are available to reduce IAP, for instance, Changes in Energy Technology, such as, switching from bio-mass fuels to cleaner fuels like SKO / Cooking gas, Improving the design and construction of locally made traditional stoves by the use of chimney, fume hoods etc., and Changes in the living environment such as, improving the state of kitchen ventilation and raising awareness among the local people about the seriousness of the kitchen air pollution and building up participatory approach in the efforts made to reduce indoor air pollution.

Recommendations

? Concrete evidence through more researches is to be established between IAP and its impact on health inclusive of diseases other than respiratory illnesses.
? Quantification of public health burden from IAP, particularly from biomass smoke.
? Identification of most smoke pollution affected areas / population size and prioritization of intervention measures required for implementation in those places.
? Identification of policy changes at local / national levels needed for successful / sustainable implementation of desired intervention measures.

Dr. Sunil Kumar Joshi
Occupational and Environmental Medicine Specialist
Asst. Professor of Community Medicine,
Kathmandu Medical College, Sinamangal