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Fuels, stoves and indoor air pollution in Jarácuaro, México
[top] [end]IntroductionThe idea of an 'energy ladder' (see Figure 1) relates improvements in household wealth with the ability of people to buy more sophisticated stoves and higher quality, less polluting fuels. The ladder model suggest that as people become richer, they may be expected to move from traditional biomass fuels to more advanced and less polluting fuels (e.g. from wood to charcoal, kerosene, and then to gas). Advancing up the energy ladder is also associated with buying fuel rather than collecting it, and with paying more for both stoves and fuel (Hosier & Dowd, 1987).
We report here on an ongoing study of the energy, health and economic implications of fuel-switching in the small village of Jarácuaro, Michoacán State, Mexico. This study challenges the traditional ladder model and explores the levels of indoor air pollution associated with the various stove types. [top] [end]Setting and methodsA wide range of stove types are used in Jarácuaro. The simple three-stone fire is mainly used by the poorest members of the community. Traditional stoves, used by many families, range from a ring of stones reinforced and shielded by a wall of clay, to more elaborate masonry enclosures with one or more fireboxes and separate openings for pots and comal (the large flat pan shown in Figures 3 and 4). A common improvement is the traditional elevated stove on a block base (Figure 2).
The households in the survey were put into four categories to build on previous research in the region (Masera) as shown in Table 1. We monitored fuel and stove use, economic status, exposure to Respirable Suspended Particulates (RSP) and trace gases (in particular CO and CO2), and illness during both wet and dry seasons for all households in the study. [top] [end]Results and conclusionsHouseholds in the region all have at least some access to a range of fuels, primarily wood and gas, and even some of the poorest families on occasion use improved stoves, or gas ranges. The fuel cost per meal prepared on three-stone fires, traditional stoves, traditional but elevated stoves, or improved 'Lorena' stoves is roughly US$ 0.02-0.07 per person per meal, which is less than half the cost of gas. A simple breakdown of stove and fuel use by home is impossible because the combination is not constant within a home. This variance is due to a number of factors: the relative prices of wood and gas; seasonal variations; employment and earnings power; and because different stove/fuel combinations are prefered for different foods.Nevertheless, a survey of the stoves in use during our visits to conduct household surveys and pollutant measurements provides one rough measure. Over 80% of cooking observed in the highest ranked homes was on gas stoves, with 60% in Type II. The proportions fell to only 30% gas use in Type III and 15% in the poorest (Type IV) households. The majority of the cooking (> 80%) in the less affluent homes was on three stone and traditional stoves.
(Contact the authors for the complete reports on these data). These changes are consistent with the technology component of the energy ladder (Smith et al., 1994). Table 1: Socio-economic ranking of families in the Jarácuaro survey
The data from Jarácuaro also suggest, however, that the simple technical energy ladder does not explain everything. Some of the cleanest and best ventilated kitchens were found among the most affluent homes, but so were some of the most polluted and poorly designed, maintained, or ventilated. The average RSP concentration did not decrease consistently as income level rose, as illustrated in Figure 7. The average particulate concentration in the lowest income homes is 449 µ/m3, but almost twice that ,845 µ/m3, in the most affluent households. The result is particularly striking as gas stoves, with emissions 5-7 times lower than traditional stoves, were mainly used by the most affluent households.
Two factors contribute to the pollution levels in more affluent homes
[top] [end]Stoves and fuel preferencesLPG use generally increased with affluence. However, families using both fuelwood and LPG (the dominant trend in Jarácuaro) spend more money on all fuel purchases than families that rely exclusively on wood. The combination of fuelwood and LPG is not simply a strategy to minimize costs or to maximize convenience. Instead, families use both types of fuel; wood for tortilla preparation and for nixtamal (corn base for tortillas) as well as several other traditional dishes and LPG for morning meals.[top] [end]Marginalization of the kitchenHealthy kitchens are easily evaluated in Jarácuaro as they have vented roof tiles as opposed to pressed cardboard or thatch materials, and generally they have cement rather than dirt floors. Kitchen improvement is, however, often overlooked as families choose to spend money on parts of the house which are seen. One woman said, we keep meaning to fix the kitchen, but no-one comes in here anyway, and we just haven't done it.'The energy ladder alone, however, does not explain the fuel and cooking choices made in rich and poor households alike. In fact, improved stove availability, educational efforts, and proper marketing can cut across socio-economic lines. This general observation is particularly important when designing rural development projects. [top] [end]References
[top] [end]Contents: Boiling Point 40: Household energy and health
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02 August 2007; Last edited:
24 September 2008; Version: 1 | |||||||||||||||||||||||||||||||||||||
Pagename: FuelsStovesAndIndoorAirPollutionInJaracuaroMexico @HEDON: KEGA | |||||||||||||||||||||||||||||||||||||
