|Boiling Point No. 21 - April 1990 (ITDG Boiling Point, 1990)|
By Dr. Jamaica Ramakrishna and Dr. Kirk R. Smith
Reproduced from the Bellerive Newsletter No. 8 December 1989.This article follows on from Emily Willingham's description, in our October 1989 Newsletter of Bellerive's Cooking to Conserves education materials.
Kirk R. Smith is Research Associate and Coordinator of the Risk, Resources and
Development Programme at the Environment and Policy Institute of the East-West Centre in Honolulu, Hawaii. His book "Biofuels, Air Pollution and Health" was published in 1987 by Plenum Press. Jamuna Ramakrishna is Research Fellow at the Environment and Policy Institute. Her recently completed dissertation deals with improved cookstoves and domestic air pollution in rural India.
Improved cookstoves are the focal point of fuelwood conservation programmes in many African, Asian, and Latin American countries. Although the stoves are almost invariably promoted on the basis of improved fuel utilization, they are often adopted by users for other reasons. Surveys, particularly in Asia, have shown that stove users place great value on the removal of smoke from the kitchen and the resulting cleaner cooking environment.
Ill health has long been associated with smoky kitchens. In fact, early improved cookstove programmer, undertaken by Gandhian organizations in the 195O's were driven by concerns regarding kitchen hygiene and the health of cooks. Most of the evidence on the health effects of chronic exposure to biofuel smoke, however, has been anecdotal. Scattered through the literature on rural energy, development, public health, and women's issues are references to eye, skin and respiratory conditions that have been associated with smoky cookstoves. Unfortunately, there has been little epidemiological work to corroborate these observations.
There are two main reasons for this apparent oversight. First, humans have been exposed daily to biofuel smoke since the first use of fire. Having survived all these centuries, the need for concern and scientific investigation may seem low compared, for example, to the less prosaic hazards of industrialization. Chronic exposure to high concentrations of biofuel smoke, however, has probably been a contributing risk factor to the generally poor health status that has prevailed throughout most of human history. It continues to be for much of the world's population. Second, an epidemiological study that would relate such exposures to health effects is extremely difficult to design. This is because of the multiplicity of risk factors that contribute to disease in rural areas of developing countries where biofuelled cookstoves continue to be used.
While a definitive health study is still awaited, we are gaining a better understanding of the exposure to biofuel smoke today. With improvements in air pollution monitoring equipment and with recent time budget studies in rural settings, a better characterization of these exposures has become available. These studies have helped in the identification of the population at greatest risk in describing the nature of their exposure. It has been found that.
· cooks using invented biefuelled stoves indoors are ex. posed to concentrations of respirable particulate several times in excess of the air quality standards recommended by the World Health Organization and agencies of various nations. Concentrations above the standards are also common for other pollutants in biofuel smoke including carbon monoxide and formaldehyde.
· biofuel smoke is a complex mixture of gases, particulate matter, and suspended droplets. Of the hundreds of constituent chemical compounds, several are known to beoxic, cancer causing, or cancer promoting.
· the population at risk is large, for about half of the world's households continue to rely on biofuel stoves although not all in unventilated circumstance.
· the groups at greatest risk from the standpoints of both exposure and vulnerability are women and their unborn babies and young children.
Although tobacco smoke is not exactly the same, there are many similarities. Evidence from both active and passive smoking studies indicates that exposures to pregnant women cooking on unvented biofuelled stoves may be sufficient to be a factor along with nutrition and other influences in causing low birth weight. Low birth weight is highly correlated with infant mortality and lifelong disability.
In addition, a study in Nepal has shown that there is a direct relationship between hours spent near the stove by infants and children aged under two years and episodes of life-threatening acute respiratory infections (ARI), which are responsible for more than a third of all childhood deaths under 5 years of age in developing countries. It is also well established that children exposed to air contaminated by their parents' smoking incur substantial excess risk of ARI even though the smoke concentrations are many times lower than those found in village homes where wood dung or crop residues are burned.
Chronic obstructive lung diseases (COLD) have been associated with long-term exposure to air pollution from various sources. Preliminary studies from Nepal and India have shown an association of COLD with women involved in cooking with biomass.
Other studies conducted in Papua New Guinea have produced conflicting results.
None of the studies mentioned above has actually measured smoke exposures as well as health effects. Neither have any intervention studies been done to determine the health improvement resulting from exposure reduction measures such as the introduction of improved cookstoves. That is obviously the direction that future research should take, given the large exposures, large population, and preliminary results of the semi-quantitative studies done so far. Until then, however, prudence would dictate that smoke exposures should be reduced wherever practical.