Indoor Air Pollution: Ongoing Research

Improving Indoor Air Quality for Poor Families Measuring the Health Effects of Indoor Air Pollution in  Developing Countries Key Findings Data Publications Presentations (Please use the free  Adobe Acrobat Reader to view  PDF files) Improving Indoor Air Quality for Poor Families:  A Controlled Experiment in Bangladesh According to theWHO Global and Regional Burden of Disease Report,acute respiratory infections from indoor air pollution (from burning wood, animal dung and other biofuels) are estimated to kill a million children annually in developing countries. A particularly heavy toll falls on poor families in South Asia andAfrica. To promote a better understanding of indoor air pollution (IAP) the research department has recently used the latest air monitoring technology and a national household survey to investigate IAP in Bangladesh. The study has found that IAP is dangerously high for many poor families in Bangladesh.   Concentrations of 300 ug/m3 for respirable airborne particulates (PM10), or greater, are common in Bangladeshi households, implying widespread exposure to a serious health hazard. The analysis of determinants of IAP verifies the IAP-reducing potential of cleaner fuels (kerosene, natural gas). However, the nationwide survey results revealed the following:  Poor households in Bangladesh (like in other parts of Asia and Latin America ) almost always use “dirty” biomass fuels, because in most rural areas, clean fuels are not available. Even where a clean fuel is available, poor households prefer to use “dirty” fuels because the relative price of the “clean” fuel is much higher. Improved stoves for biomass combustion could help, but the World Bank survey found almost no adoption of improved stoves despite widespread promotional efforts in Bangladesh.  Households report non-adoption for a variety of reasons, including high price and maintenance costs, inconvenience, and incompatibility with food preparation traditions. Thus, neither clean fuels nor improved stoves offer strong prospects for reducing IAP in the rural areas in the near future.

Click here to view larger image         Movie clip of experiments in Bangladesh Determinants of Indoor Air Pollution Indoor Air Pollution Construction of a brick house Click here to view larger image Construction of an "attached" kitchen Click here to view larger image Monitoring air in an "open" kitchen Click here to view larger image

The study further revealed that a more promising direction is the use of commonly available construction materials, space configurations, cooking locations, and the use of doors and windows, to improve ventilation. A combination of these features can and have produced large differences in IAP exposure. 

Some poor households using “dirty” fuels enjoy indoor air quality normally associated with clean fuels, while other equally poor households suffer from pollution levels 10 times the international safe standard.  Since many poor households already have some of the relevant dwelling characteristics, they are clearly acceptable and affordable in Bangladesh. The research, therefore, has identified ventilation characteristics of houses and household ventilation practices as potentially important determinants of IAP, and these can be modified to improve air quality.

The first-round research has only been able to consider a subset of feasible measures of ventilation that might yield significant benefits.   To promote better understanding of these relationships, current research in Bangladesh has conducted a controlled experiment to estimate the impacts on air quality of slightly altering construction materials, space configurations, and cooking locations.

In order to avoid disappointment stemming from the reluctance of poor families to adopt innovations that are unfamiliar, unsupported by existing services, and potentially costly to maintain, the experimentation in the ongoing research is confined to structural arrangements that are already common among poor households in Bangladesh, such as construction materials and cooking locations.

Collaborating Institution:   Development Policy Group, Bangladesh
Expected Completion Date:  March, 2007

Measuring the Health Effects of Indoor Air Pollution in Developing Countries: The Case of Bangladesh

The design of cost-effective indoor air pollution (IAP) reduction strategies in developing countries has been hindered by lack of information about actual respirable particulate concentrations and its impact on health in poor households. The high costs of monitoring air quality and conducting medical tests in the village environment have limited research efforts.

Research on the health impacts of IAP requires detailed data on both exposure and illness outcomes. Only one study has been conducted in rural Kenya to estimate exposure-response relationships for indoor smoke. Extrapolation of air pollution-related health studies conducted in developed countries is not a reliable analytical approach given the significant difference in pollution levels in developed and developing countries. Hence, lack of research on the exposure-response relationship has been highlighted as one of the serious knowledge gaps in understanding the health impacts of IAP in developing countries.

The current research design involves a epidemiologic cross-section study in Bangladesh to reduce the knowledge gap.  To promote a better understanding of IAP, the World Bank has conducted a two-year indoor air monitoring study in Bangladesh in 2003. 

Using the latest air monitoring technology and a national household survey, this study has shown that IAP is dangerously high for many poor families in Bangladesh. Later on, the WHO sent a group of doctors to measure lung capacity of members of the households where the World Bank has monitored the quality of indoor air.

In the ongoing research, the health effects of IAP in Bangladesh are being estimated by combining the World Bank data on indoor air quality and the WHO clinical data on lung capacity. In addition, the study is testing the reliability of self-reported health data for their applicability in future research. 

Expected Completion Date: June 2008

Improving Indoor Air Quality for Poor Families in Bangladesh

In the controlled experiments, provisions were made for cooking fuel combustion in four configurations that simulate common cooking arrangements in Bangladesh: inside the house (within-dwelling); in a space attached to it (attached kitchen); in a space enclosed by walls and a roof at a little distance from the house (detached kitchen); and in the open air. 

The wall materials of attached and detached kitchens as well as living spaces varied. Wall types  included thatch, mud, tin and brick, and roof types included thatch, tin and concrete. The experiments also allowed for turning on a ceiling fan in the living space. A variety of energy sources were included: clean fuels (kerosene, liquefied petroleum gas), wood, cow dung, and other biomass fuels (rice husks, jute etc.). 

Regression analysis of the experimental data yielded a number of conclusions:  

• First, outdoor air pollution is a highly significant determinant of indoor ambient pollution levels, particularly in the high-dust season. 
• Second, during the high-dust season, results suggest that the air quality in interior kitchens is much better than outdoor or detached facilities.  This is not true during the low-dust season (when rain is frequent), but then it is difficult to cook outside. 
• Third, building materials make a significant difference for indoor pollution during the high-dust season.  As far as the indoor air quality is concerned, in kitchen areas, brick walls are significantly more air-trapping than mud walls, which are, in turn, significantly more air-trapping than thatch or tin walls.  For kitchens, tin roofs provide better air quality than thatch roofs.  In living rooms, tin walls provide better air quality than mud walls, which in turn are better than brick or thatch walls.  In summary, tin seems to be the building material that contributes the most to healthy air quality, followed by thatch, mud, and brick.  Ceiling fans also provide significant benefits in the high-dust season. 
• Fourth, air quality monitoring results clearly show that IAP from cooking smoke can be a serious problem in living rooms as well as kitchens.  By implication, all members of the household are equally exposed to indoor air pollution. 
• Finally, among fuels, seasonal conditions seem to affect the relative severity of pollution from wood, dung, and other biomass fuels.  However, there is no ambiguity about their collective impact.  All are far dirtier than clean fuels.

Recommendations  

• Pollution from the cooking diffuses rapidly and fairly completely into living spaces. If cooking with clean fuels is not possible, then building the kitchen with tin walls and providing proper ventilation in the cooking areas will enable a better indoor health environment.
• The importance of outdoor pollution in determining indoor air quality suggests that an optimal cooking location should be determined that takes seasonality (e.g., the dust season) into account.
• It is necessary to factor in the interaction between outdoor and indoor air pollution in efforts to improve indoor air quality. For example, the use of chimneys may improve indoor air in individual households, or when dwellings are dispersed, but cooking smoke emerging from chimneys in a cluster of households is likely to aggravate outdoor air pollution. The polluted outdoor environment, in turn, will adversely affect indoor air quality for all households in the cluster.  

Improving Indoor Air Quality for Poor Families: A Controlled Experiment in Bangladesh  by Susmita Dasgupta, Mainul Huq, M. Khaliquzzaman, and David Wheeler, August 2007. Processed.

Read Me File (PDF 14kb)
Kitchen Configurations in Bangladesh (Powerpoint 18kb)
Minvol Readings: Pre-Monsoon (Excel 85kb)
1) Primary data on 24-hour average PM-10 concentrations in indoor air of 167 combinations constructed for the experiment in Bangladesh as recorded by Airmetrics MiniVol Portable Air Sampler during pre-monsoon period of 2005. The detailed information include: (i) construction material of the kitchen and living room, (ii) configuration of the kitchen, (iii) type of fuel used for cooking, and (4) position of the stove.
2) Primary data on PM-10 concentrations in ambient environment.
Minvol Readings: Post-Monsoon (Excel 215kb)
Primary data on 24-hour average PM-10 concentrations in indoor air of 337 combinations constructed for the experiment in Bangladesh as recorded by Airmetrics MiniVol Portable Air Sampler during post-monsoon period of 2005 and early 2006. The detailed information include: (i) construction material of the kitchen and living room, (ii) configuration of the kitchen, (iii) type of fuel used for cooking, and (4) position of the stove.
2) Primary data on PM-10 concentrations in ambient environment.
PM-10 PD RAM Readings: April 2005 - December 2005 (Excel 16,933kb)
Primary data on PM-10 concentrations in indoor air of 89 combinations constructed for the experiment in Bangladesh. In each case PM-10 concentrations were recorded by Thermo Electric Personal DataRAM (pDR-1000) at 2-minute intervals for a 24-hour period. Indoor air for these houses were monitored during April 2005-December 2005. The detailed information include: (i) construction material of the house, (ii) configuration of the kitchen, and (iii) type of cooking fuel.
PM-10 PD RAM Readings: December 2005 - May 2006 (Excel 15,604kb)
Primary data on PM-10 concentrations in indoor air of 89 combinations constructed for the experiment in Bangladesh. In each case PM-10 concentrations were recorded by Thermo Electric Personal DataRAM (pDR-1000) at 2-minute intervals for a 24-hour period. Indoor air for these houses were monitored during December 2005-May 2006. The detailed information include: (i) construction material of the house, (ii) configuration of the kitchen, and (iii) type of cooking fuel.

Improving Indoor Air Quality for Poor Families: A Controlled Experiment in Bangladesh by Susmita Dasgupta, Mainul Huq, M. Khaliquzzaman,  and David Wheeler, October 2007.

Model Houses/Plans  (Powerpoint 480kb)
Indoor Air Pollution: A Controlled Experiment in Bangladesh (PDF 3,725kb)